Introduction

The global population is predicted to approach 9 billion by 2050, consequently, global food production will have to be increased by 70% to provide sufficient food (FAO—Food and Agriculture Organisation of the United Nations 2009). Rice is one of the most essential food commodities that plays an important role in feeding the world's population with a projected consumption of 561,885 kt per capita in 2024. The global rice market is dominated by the developing countries with a projection of consumption of 96.48% while the developed countries will be consumers of only 3.51% of the rice global production in 2024 (OECD-FAO-2015). To provide this level of food production requires substantial crop protection from insect invasion and diseases to ensure optimal yields and reduce losses. Hence, the use of pesticides has become an essential element to ensure successful crop growth and increased productivity (Handford et al. 2015). Indeed, pesticide use has increased by an average of 2.3 million tonnes in 1990 to 4.1 million tonnes in 2016 (FAOSTAT 2021a, b). As a result, pesticides may not only persist in the environment and affect wildlife but will increase the burden on human health through residues in the food chain (Reeves et al. 2019). Consumers nowadays are very aware of the provenance of their food and indeed food safety and thus demand food free from chemical contaminants.

Risk assessment is a critical step when regulatory bodies consider the authorisation of pesticides and their use on food crops (Hamilton et al. 2004). Pesticide use must be monitored and controlled for impacts on human health and the environment nationally and globally (Miraglia et al. 2009). The resultant pesticide residues are defined as a substance found in food, in commodities, in water and is the consequence of the use of a pesticide (Leong et al. 2020). In this review pesticides are explored in terms of their uses in agriculture, their impact on human health, how climate change affects the use of pesticides and the legislation surrounding pesticides, including the impact on trade. In addition the challenges in implementing and maintaining them are explored. The gaps that currently exist in pesticide regulations are examined. As a case study, the focus has been placed on one of the world’s most important cereal crops, rice, to help illustrate these challenges and legislative gaps. Based on the highest number of alerts/notifications on the RASFF system, the specific pesticides, tricyclazole, carbendazim, thiamethoxam and acephate were selected for consideration.

The aim of this systematic review is to provide a comprehensive overview and understanding of the decisions required to deliver safe food and protect public health, expose knowledge, or evidence gaps in order to promote further research to address these shortcomings, in the context of pesticides.

Methods

The Campbell Methods Guide (Kugley et al. 2017) was followed for the retrieval of information for a systematic review. The PRISMA extension for scoping reviews (Tricco et al. 2018) was followed to elucidate the main drivers, criteria and sources of evidence and demonstrate which products are used to assist in food safety standards and decision making. Relevant articles were initially identified using ‘Title’ and ‘Abstract’ screening. All citations were exported to EndNote and duplicates were removed prior to full text screening. The screening results have been presented in a modified PRISMA chart.

Search Strategy and Data Extraction

This review aimed to:

  1. a.

    identify the challenges associated with pesticides and pesticide residues.

  2. b.

    determine the impact of pesticide use on trade and human health.

  3. c.

    How will climate change affect the use of pesticides?

  4. d.

    examine the legislation adopted to protect consumer health in terms of rice and rice products. Specifically regulatory limits for, tricyclazole, carbendazim, thiamethoxam and acephate were selected for consideration.

  5. e.

    provide an overview of the impacts of these regulations on the economies of various countries.

  6. f.

    expose knowledge and identify gaps in harmonising globally the safety standards and legislation for pesticides and pesticide residues.

Study Design

The aim of this systematic review was to perform an in-depth analysis of pesticide legislation, focusing on rice, to understand the gaps that exist in the harmonisation across different countries. Tricyclazole, carbendazim, thiamethoxam and acephate were the pesticides selected for consideration.

Electronic searches of the following databases were conducted: Scopus, Web of Science and PubMed. In addition, Google, Bing and Yahoo search engines were interrogated to identify relevant international and government agencies associated with food safety regulations for pesticides and additional grey literature relating to the topic. Search details and inclusion and exclusion criteria are described below. Specific grey literature sources are included (but may not be an exhaustive list):

  1. a.

    The European Commission.

  2. b.

    The European Food Safety Authority.

  3. c.

    The World Health Organisation/Food and Agriculture Organization of the United Nations/The Joint FAO/WHO Expert Committee on Food Additives (JECFA)/The International Food Safety Authorities Network (INFOSAN)/The Codex Alimentarius Commission (CAC).

  4. d.

    The US Food & Drug Administration (US FDA).

  5. e.

    The Food Safety and Standards Authority of India (FSSAI).

  6. f.

    The National Food Safety Standards System, China.

  7. g.

    The Ministry of Health, Labour and Welfare (MHLW), Japan.

  8. h.

    The Ministry of Food and Drug Safety, South Korea.

  9. i.

    The National Bureau of Agricultural commodity and Food Standards, Thailand.

  10. j.

    The Government of Canada

  11. k.

    The Food Standards Agency

  12. l.

    The Rapid Alert System for Food and Feed (RASFF)

Inclusion Criteria

Studies were identified by searching the literature published in English only, and only studies from 1996 until June 2021 were included using the rationale that older data would be less reliable. No restrictions were placed on geographical regions and no study design was excluded. Considering their frequent detection in rice and consequent trade issues (FOODAKAI 2021), only publications specifically concerning carbendazim, tricyclazole, thiamethoxam and acephate were included.

Exclusion Criteria

Any publications with specific pesticides other than carbendazim, tricyclazole, thiamethoxam and acephate were excluded. Conference proceedings were excluded.

Search Strategy

The following keywords and search strings were applied to the electronic literature databases outlined previously. These key search terms were used to search for grey literature. This approach has been piloted in Scopus.

Search

Keyword search

#1

Pesticide* AND Rice* AND safety OR regulation* OR guideline* OR legislation OR standard* OR stakeholder* OR risk AND management OR risk assessment OR policy* OR economy* OR market* OR consumers OR impact OR products OR HACCP*

#2

Tricyclazole AND rice AND safety OR regulation* OR guideline* OR legislation OR standard* OR stakeholder* OR risk AND management OR risk AND assessment OR policy* OR economy* OR market* OR consumers OR impact OR products OR HACCP*

#3

Carbendazim AND rice AND safety OR regulation* OR guideline* OR legislation OR standard* OR stakeholder* OR risk AND management OR risk AND assessment OR policy* OR economy* OR market* OR consumers OR impact OR products OR HACCP*

#4

Thiamethoxam AND rice AND safety OR regulation* OR guideline* OR legislation OR standard* OR stakeholder* OR risk AND management OR risk AND assessment OR policy* OR economy* OR market* OR consumers OR impact OR products OR HACCP*

#5

Tricyclazole AND rice AND food AND residues

#6

Carbendazim AND rice AND food AND residues

#7

Thiamethoxam AND rice AND food AND residues

#8

Pesticides AND politics AND global

#9

Pesticides AND Codex AND MRL and consumers AND risk AND assessment AND food AND safety

#10

Pesticides AND food AND safety AND Stakeholder

#11

Pesticides AND exports AND food AND safety

#12

Pesticides AND global AND harmonization

#13

Pesticides AND food AND safety AND policy AND human AND health

#14

Pesticides AND food AND safety AND regulation AND trade

#15

Food AND safety AND big AND data AND pesticides

#16

Pesticides AND economic AND impact AND of AND pesticides AND regulation and rice

Critical Appraisal

Critical appraisal of the publications ensured that only relevant high-quality studies were included and low-quality studies excluded. This step was based on the Critical Appraisal Skills Program (CASP) Tools Checklists (Long et al. 2020). To be included in the review, papers needed to satisfy the following citation, title and abstract screening questions:

  1. 1.

    Does the citation indication of the publication fall within the time period specified?

  2. 2.

    Are the title and abstract in English?

  3. 3.

    Were the aim and objective/s of the study clearly communicated?

  4. 4.

    What were the main findings of the paper and did they address the objectives of our review?

  5. 5.

    Did the study address its aim?

  6. 6.

    Strengths?

  7. 7.

    Limitations?

  8. 8.

    Did the author acknowledge study limitations?

  9. 9.

    Were the findings consistent with other published literature?

  10. 10.

    Include/Exclude from review?

Both qualitative and quantitative studies were included in the review.

Overall, 34 papers passed the critical appraisal process and were included in the review, outlined in Fig. 1.

Fig. 1
figure 1

Summary of screening and critical appraisal processes (according to PRISMA guideline)

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Synthesis of Information

Scientific publications and grey literature were collated to provide an overview of the current challenges with pesticides in terms of (i) pesticide residues, trade, human health, climate change and environment; (ii) examine the legislation adopted to protect consumer health in terms of rice and rice products. Specifically regulatory limits for, tricyclazole, carbendazim, thiamethoxam and acephate were selected for consideration; (iii) providing an overview of the impacts of these regulations on the economies of various countries; (iv) exposing knowledge and identifying gaps in global harmonisation of the safety standards and legislation for pesticides and pesticide residues.

Current Challenges with Pesticides

The ecological framework chart (Fig. 2) highlights the interrelated challenges with pesticides and pesticide residues, their impacts on trade, human health, climate change and governmental regulation. The greatest concern is whether pesticides and their residues pose risks for human health both in the context of acute and chronic exposures. Pesticides have wide ranging impacts on human health, from acute immediate responses to longer term chronic illnesses (Leong et al. 2020). The requirement for inspection and sampling in both the exporting and importing countries places an administrative burden on the source and destination countries involved in trade. Finally, climate change and water scarcity are requiring elevated concentrations of pesticides applied in agriculture and consequently increased uptake of pesticides into plant roots.

Fig. 2
figure 2

An Ecological Framework Showing the Interrelated Challenges and Impacts with Pesticides: Pesticide Residues, Trade, Human Health Climate Change

Full size image

Pesticide Residues in Food and Agro-Commodities

One of the main issues with the use of pesticides in agriculture is the fact that their traces (residues) might accumulate and remain in food. Annually, the European Food Safety Authority (EFSA) prepares a report on 182 commonly detected pesticide residue levels in select vegetable products, cow milk and swine fat for the European market. In 2019, 96.1% of randomly tested food samples revealed pesticide residue levels below the Maximum Residue Limits (MRL), i.e. the maximum acceptable levels of pesticides in food and agricultural products as prescribed by the European Commission. However, 3.9% of these samples exceeded the MRLs allowed by the EU legislation (Cabrera and Pastor 2021). In the RASFF Annual report 2020, 667 notifications for pesticides residues were reported with a rate of 4.79% (32 notifications) provided to rice and rice products. After notification, the course of action taken resulted in rejection of the product at the border, recalls, and destruction of the trade product (EU (2021) Rapid Alert System for Food and Feed (RASFF)). Furthermore, as part of the EU-coordinated control program (EUCP), measurements taken on samples of crops grown in the EU and on samples of imported products revealed the presence of non-approved (in the EU) pesticide residues including acephate and thiamethoxam with MRLs exceeding the allowable limits. As part of the EUCP framework and National Programs (NP) of pesticide monitoring for each reporting country, these testing efforts revealed 7.8% of samples with a higher MRL exceedance and 5.6% with a higher non-compliance level when the sample origin was from a third country. This contrasts with the EU-derived samples, which showed 2.7% MRL exceedance and 1.3% non-compliance (Cabrera and Pastor 2021). The number of tests performed and reported fluctuated greatly depending on the country. Two extreme testing values, for example, 1.5 samples per 100,000 inhabitants for the UK and 125.5 samples per 100,000 inhabitants for Lithuania. The overall mean for all reporting countries was 18.6 samples tested per 100,000 inhabitants (Cabrera and Pastor 2021).

In 2019, EFSA conducted acute and chronic exposure assessments for 182 pesticides. The data showed that there was no appreciable threat to the health of consumers. This conclusion was, however, based on the risks associated with individual pesticide. Even though multiple pesticide residues were detected in 44.1% of samples, in this study, the risk assessments targeted each single pesticide separately and did not study their combined effects. As no MRL exceedance for any of the detected pesticides was recorded, the samples were labelled as compliant (Cabrera and Pastor 2021). In the UK, 2.52% of the samples tested contained a residue above the MRL (PRiF 2020).

The analysis of 476 pesticide residue levels was conducted by the US Food and Drug Administration (FDA) on fresh vegetables from 1996 to 2006. This report showed that domestically grown vegetables had lower harmful residue rates than imported produce. It was found that contamination rates varied according to the country of origin but that it was not related to the wealth of a region or country. Of the total tested US import samples, 37.6% revealed the presence of pesticide residues and 5.2% of the samples contained levels above regulatory limits or the presence of illegal pesticide residues. By comparison, 32.9% of the domestic test samples in the US contained some pesticide residues, of which 1.6% were detected as illegal pesticide residues. The level of testing (i.e. tests per kilogram of vegetables imported) varied with regards to the country of origin and the crops, with the highest harmful rates related to small vegetables, especially the above-ground edible components. Out of a total of 476 pesticide residues screened by the FDA, 14 pesticides accounted for 66% of all violations (Galt 2010).

Impacts of Pesticides use on Trade

With the disparity and lack of global harmonisation of MRLs for pesticides, the large-scale use of pesticides has become a major issue in a number of exporting countries demonstrated by the rate at which they fail to comply with the MRLs of the destination importing countries. Consequently, inspection and sampling are undertaken in both exporting and importing countries to demonstrate compliance with the required national legislation. While exporting countries are expected to meet the permitted pesticide residue levels of the importing countries, the ability to undertake such monitoring in developing countries is often limited. Indeed, this can also be the case in developed countries, as shown by the US, a major importer of fruits and vegetables, where less than 1% of import shipments are inspected by the Food and Drug Administration (FDA). With such a low rate of import inspection, there is a low incentive to ensure compliance (Neff et al. 2012). Surprisingly and worryingly, in the US, the Environmental Protection Agency allows the export of non-approved or non-registered pesticides, particularly to developing countries that lack pesticide legislation or a framework to evaluate the imported pesticides (Handford et al. 2015). According to the Rotterdam Convention on the Prior Informed Consent (PIC) Procedure for Certain Hazardous Chemicals and Pesticides in International Trade, an exporting country must inform the importing country regarding the use of any banned pesticide, share pertinent information and await that country’s specific agreement before exporting the substance. However, these non-approved pesticides may well be returned to the exporting countries through pesticide residues present in commodities, creating a boomerang effect (Watterson 1990). The FDA reported that unauthorised pesticide residues that do not have approved MRLs in the US were commonly detected in imported commodities. The detection of these unauthorized pesticides represented 95% of all violations (Reeves et al. 2019).

In the same context, EU regulations on the export and import of hazardous chemicals, as defined in Regulation (EU) No 649/2012, encourage shared responsibility and cooperative efforts in the worldwide movement of hazardous chemicals and employ the Rotterdam Convention on Prior Informed Consent (PIC). Prohibited pesticides in the EU are also exported to developing countries under the name of a substance or pesticide mixture. This gap was brought to the attention of the public by non-governmental agencies in the EU (Europarl 2021). In response, on October 14th, 2020, the European Commission published “Chemicals Strategy for Sustainability Towards a Toxic Free Environment”. As a part of the European Green deal and the framework of the cooperation with third countries, the EU commission promised that banned chemicals in the European Union would not be produced for export purposes. In the case of the implementation of this strategy by the European Parliament, the legislation on hazardous chemical exports may be amended (EC 2020).

There are a wide range of pesticides used in rice production and Codex has established 105 MRLS for rice (38 MRLs), rice husked (23 MRLs), wild rice (1 MRL), polished rice (18 MRLs). Rice and wild rice are also regulated under the category of cereals grains (cereals, rice and wild rice) (35 MRLs) (Codex Alimentarius FAO 2021). The disparity in the MRLs applied by trading countries, between those applying Codex MRLs, those applying stricter MRLS or more relaxed MRLs hinders trade in rice and may lead to rejection or destruction of the product.

Impacts of Pesticide use on Human Health

Pesticides can have a negative impact on human health (Leong et al. 2020), and the World Health Organization (WHO) considers them as a severe public health problem. The exposure can be chronic or acute when pesticides are applied to agricultural crops or close to residential areas, if they persist in the environment or are consumed via food containing pesticide residues. Pesticides have a wide ranging impact on human health, from acute illness with headaches, vomiting and poisoning to chronic illness including cancer, neurological damage and endocrine disruption and can ultimately be lethal (Leong et al. 2020).

The Intergovernmental Forum on Chemical Safety (IFCS) defines an acute pesticide poisoning as a health impact or disease due to a pesticide exposure within the first 48 h. Boedecker et al. (2020), in their systematic review on world-wide unintentional, acute pesticide poisoning (UAPP), estimated the occurrence of up to 385 million cases annually with 11,000 cases of mortality reaching 44% of the farmers and farmworkers in agricultural communities. The incidence of yearly non-fatal UAPP peaked in developing countries in regions such as southern Asia (65%), south-eastern Asia (51%) and East Africa (54%) with a very high prevalence in Burkina Faso (83%), Kuwait (82%) and Pakistan (81%). The lowest incidence rates were in North America (0.08%) and Australia (0.05%). The incidence of yearly non-fatal UAPP among the farming and occupational population has risen dramatically over the past three decades from an initial estimate of one million cases of UAPP and 2 million cases of intentional acute pesticide poisoning per year as estimated by the WHO (Boedeker et al. 2020). Numbers have been under estimated for 30 years since they relied only on hospital data. In addition, mild intoxications and loss of capacities were unreported, as fatalities received most of the attention. The lack of differentiation between unintentional and intentional APP led to an improper response by the WHO, even if it had been acknowledged as a serious health problem. The outcome of this attention deficit showed inadequate efforts in the development of measures to quantify and globally prevent UAPP and IAPP (Boedeker et al. 2020).

Health effects from pesticide use are an ongoing concern within the European population, demanding a continuous evaluation of the European pesticide policy. Since health impacts are linked to the choice and use of pesticides, a better knowledge of applied substances is essential (Fantke et al. 2012). For instance, in 2003, adverse health outcomes and associated damage costs were quantified from exposure to 133 pesticides used in 24 European countries. This comprised almost 50% of the total pesticide mass applied in 2003. Thirteen of these 133 substances were specific to 3 crop classes (vegetables, grapes/vines and fruit trees) and contributed to 90% of the overall health impacts of approximately 2000 disability-adjusted life years. Thirty-three of the 133 assessed substances were responsible for 20% of these adverse health outcomes and are now prohibited in the European market in accordance with the current legislation.

Knowledge of good practices such as studying labels carefully, the use of instructions and understanding the hazardous nature of a pesticide are not sufficient to reduce the impacts on human health. A gap still prevails between the knowledge of the importance of safety measures and the application of appropriate safety behaviours (Sharifzadeh et al. 2019). In addition, economic pressures constrain farmers’ responses to the application of more cost-effective one-time spray pesticides. This may lead to high levels of residues of authorised pesticides or the application of non-registered pesticides on a specific crop (Galt 2010).

One of the major causes of adverse health outcomes among farmers is improper safety behaviour. Human exposure to pesticides is strongly correlated with inadequate protection and a lack of caution and limited understanding of the risks when working with these chemicals. Currently there is a knowledge gap surrounding farmers’ safety behaviour in the context of chemical exposures particularly in developing countries like Iran. A recent study by Sharifzadeh et al. (2019) provided a concise framework for better comprehension and measurement of farmers’ safety behaviour with pesticide use. This study also provided useful inputs for the design of efficient interventions strategies that could support the implementation of farm safety measures in Iran (Sharifzadeh et al. 2019). Only 8.9% of farmers stated that they used Personal Protective Equipment (PPE), and just 8.6% were found to follow proper use of the chemical, with 2.7% following the recommended cleaning directions after using a pesticide. Overall, only 2.4% of farmers demonstrated the appropriate behaviour and practice needed to avoid health issues. Gaps in safety behaviour are evident through improper use of chemicals, a restricted movement and lack of flexibility when using PPE, a high cost of the application of the safety measures especially with low-income farmers, a lack of medical check-ups to ensure a certain awareness of the potential risk when using pesticides (Sharifzadeh et al. 2019).

In Northern Italy, rice and corn are the primary cultivated crops involving small and medium enterprises (SMEs) (Rubino et al. 2012). Farmers working in hot climates generally do not use protection and this puts their health at a greater risk. Risk assessments on farmers are rarely performed (Rubino et al. 2012), and programs monitoring the exposure of workers spraying pesticides on crops are insufficient (Van den Berg et al. 2020). Furthermore, gaps are reported in health risks by 87% of 54 African countries, highlighting a lack of a central data collection regarding pesticide poisoning information, guidelines and training program in public health (Van den Berg et al., 2020).

Snelder et al. (2008) in a risk assessment study on small farm holders in the Philippines reported that most of the farmers never received training from the Department of the Agriculture, on the correct use of pesticides, safety methods, spraying techniques and instructions regarding the use of personal protective equipment (PPE) due to funding limitations. Performing risk assessments to understand farmers’ exposure to pesticides and the impact on their health is lacking in many countries where moderately and highly hazardous pesticides (classified by the WHO) in addition to the pesticides restricted in the US are freely on sale (Snelder et al., 2008).

Impact of Climate Change on the use of Pesticides

Today climate change is at the centre of the debate on the global food system. Its effects are well-known and listed as follows: rising temperature, rainfall patterns and drought, seasonal variation, physiological response of crops to CO2 enrichment, changes in soil quality, forced relocation of cropping systems due to water scarcity, change in crop production, increase in plant diseases and insect invasion, to name but a few. The direct impacts on pesticides due to climate change include a lowered bio-activity of substances due to water scarcity, change in soil quality due to water scarcity and degradation due to exposure to high atmospheric temperature (Miraglia et al. 2009). The expected reduction of soil organic matter with elevated temperatures often results in greater root uptake of pesticides that would otherwise be bound to organic matter. Additionally, the physicochemical characteristics of a given pesticide may cause it to be evaporated more quickly at higher temperatures. Many pesticides work poorly in arid conditions (Muriel et al. 2000), often requiring larger dose levels or more frequent applications to provide adequate crop protection. On the other hand, some evidence of faster degradation of pesticides exists due to exposures higher temperatures (Bailey 2004). The impact of climate change on the use of the pesticides and their efficiency is influencing food systems and food security (Miraglia et al. 2009). The influence of climate change will impact the use of pesticides according to good agricultural practice (GAP). Indeed, the current GAP may not be suitable for the future status and sustainability of crops (Miraglia et al. 2009). Additionally, although many countries are required to have pesticide residue monitoring practices, there is a lack of global harmonisation. One of the reasons for this is a wide range of analytical technologies employed with different degrees of accuracy and performance. Owing to pesticide authorisation at a domestic level, international level oversight is often lacking.

To assess the effect of alterations in pesticide use on food safety due to climate change, it will be critical to further harmonise the monitoring of pesticide residues at an international level. Monitoring at this level, in the EU for example, will be essential as this will provide the requisite authorisations for pesticide usage and their modifications across nations. Finally, exploring methodologies that derive pesticide usage data for developing and integrating better models will be required to predict changes and trends in crops, cropping systems, plant pests and pesticide usage (Miraglia et al. 2009).

Although many countries have implemented pesticide residue monitoring, this does not ensure that they employ the same analytical methods. Besides, the results of such monitoring are not easy to compare. Additionally, each country authorises the use of a pesticide at a national level, and on certain crops, but this information might not be internationally relayed in all cases. Climate change is likely to lead to increased use of pesticides, necessitating further food safety assessment. The evaluation of the direct impacts of climate change on pesticide utilisation will require special attention to national and international harmonisation of pesticide residue monitoring, knowledge and changes to authorisations, methodologies to obtain data and development of models for predicting alterations in crops, cropping systems and pests (Miraglia et al. 2009). Even when pesticides are removed from an approved list and not in use any more (legally), it might continue to persist in the environment and accumulate in the food chain (Reeves et al. 2019).

Legislative Framework, Standards, and Regulations on Pesticides

General Pesticide Legislation

Pesticide legislation varies considerably across different countries. Pesticide lifecycle management covers a variety of subjects ranging from legislative and regulatory activities, manufacturing practices, applications, risk reduction, monitoring and administration of the disposal of pesticide waste. In general, regulations in developed countries are more stringent than in developing countries which often lack the required legislation and policies. Implementation and enforcement of policies, lack of resources and staff to run pesticide analyses and the need for scientific expertise pose limitations in a number of developing countries (Handford et al. 2015).

The Codex Alimentarius Commission (CAC), a commission from the joint WHO and FAO organisation, established standards for pesticide residues with regards to use and developed international standards for food products. It provides a framework for stakeholders at different levels of the food supply chain to reduce the risk of contamination and final product toxicity (Europarl-data 2021).

Globalisation of the food system allows the risks associated with food safety to be shared, ultimately for the global public good. These shared risks encompass pesticide residues, microbial pathogens, and mycotoxins (Camanzi et al. 2019). The Codex MRL is the highest level of pesticide residue that is lawfully permitted in or on food or feed, when it is applied correctly in agreement with Good Agricultural Practices (GAP). These are adopted annually by CAC as the international voluntary standards after the recommendation of the Codex Committee on pesticide residues (CCPR). Each year, the CCPR meets on three occasions, and at the annual CAC meeting, following the recommendation of an independent body of experts, the Joint Meeting on Pesticide Residues (JMPR) establishes global standards of MRLs to facilitate free international trade of quality-compliant consignments, ensuring the safety of consumers (Ambrus 2016) and regulating daily intakes. A current major gap is the implementation of guidelines on many farming systems with the aim of producing a food commodity that will be safe and healthy for consumers using sustainable methods and that will consider in a larger spectrum the economical, the social and the environmental incidence of pesticides. It should be noted that MRLs are not a value that will ensure human safety from pesticide exposure. An MRL does not provide a measure of the level of pesticide residues that is safe for humans (Leong et al. 2020).

To determine whether a pesticide poses an unacceptable risk to the consumer, the FAO has established toxicological reference values, which are the Acceptable Daily Intake (ADI) and the Acute Reference Dose (ARfD). The ADI estimates the amount of a pesticide present in food or drinking water that can be consumed daily over a lifetime without notable health risk to the consumer, based on all known facts at the time of the evaluation. It is measured in milligrams of pesticide per kilogram of body weight per day. The dietary intake of pesticides is assessed by merging national or regional food consumption measurements with the estimated residues in food and/or drinking water. The consumer is deemed to be adequately protected when the estimated long- and short-term dietary intake of pesticide residues does not surpass the ADI and the ARfD (FAO 2021).

The European pesticide legislation has EU MRLs in place and are usually more stringent, when compared to those of CODEX. In Europe, the approval of a new pesticide is performed by EFSA and the Member States after an evaluation in a process that lasts at least for 3 years. The European legislation spans over 1100 pesticides used in agriculture and covers 315 fresh products as well as commodity products. An MRL of 0.01 mg/kg is automatically in place as a default value if a pesticide is not covered by the EU legislation (Unnevehr 2007). Van Den Berg et al. (2020) carried out a survey in 2017–2018 to assess the global status of pesticide lifecycle management, where they uncovered gaps with the management of pesticide, indicating that pesticide efficacy and safety are likely to be compromised at different stages of a pesticide lifecycle and at varying degrees across the globe. Low-income countries were found to have the most gaps, affecting pesticide safety measures and efficacy, with inadequate measures taken to mitigate the hazards of pesticide exposure and contamination (Van den Berg et al. 2020).

In addition to the Codex MRLs, countries can also establish national pesticide MRLs (Maximum Residue Limits | CODEXALIMENTARIUS FAO-WHO). This addresses the variations in food habits and risk incidences across different geographic locations. Although a tentative international pesticide law harmonisation is organised by the EU, the Codex Alimentarius Commission and the North American Free Trade Agreement (NAFTA), the MRLs have remained highly variable. A harmonised pesticide legislation will serve trade, the environment and above all will protect public health globally. Nevertheless, protecting public health by means of food safety remains a challenge. Policymakers need to implement a risk management plan (Yen and Esworthy 2012). An existing MRL can be modified to accommodate trade and import of a produce, especially when its residues may exceed the national MRL (Gov.UK 2021).

Nonetheless, it is important to consider that, depending on the type and form of food consumed (fresh, frozen, or canned) in the diet, the levels of residues present in the food may be different as well as the effect of consuming a single food item in large quantities may result in higher short-term exposure than a typical long-term or average consumption (Hamilton et al. 2004). While risk assessment can only be carried out for one type of pesticide at a time, the samples might contain several pesticide residues, and the synergistic effect of multiple residues present is highly unlikely to be considered by the legislation governing human health risks.

Pesticide Regulations (the USA vs Europe)

The politics of consumerism and environmental risk regulation has evolved over the past five decades in the US and Europe and shows that regulations are often different for the same risk. During a thirty-year period between 1960 and 1990, US health, safety, and environmental regulations became stricter, risk averse and more thorough, than those in use in Europe. However, in the intervening years since 1990, global regulatory oversight has shifted to Europe. Pressure on political leaders to act regarding the risks posed by pesticides has risen among the European public but declined among Americans. EU regulations are more stringent and they are more willing to regulate risks while those in the United States are more in line with partisan divides. Regulatory control on businesses are considered by American policymakers as well as receiving high levels of scientific advice (Vogel 2012). The disparity between MRLs for the pesticides considered in this study have been outlined in the section “MRLs in Rice”, Table 3. This highlights that while MRLs have been established for these pesticides in various developed and developing countries, often the limits are more relaxed in the developing countries and strictest in the EU.

Pesticide Registration and Sales

The major authorities governing pesticide regulations in the USA, are the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), and Sect. 408 of the Federal Food, Drug and Cosmetic Act (FFDCA). The Environmental Protection Agency (EPA) regulates the sale and use of pesticides in the USA via registration and labelling of pesticide products. The sale of pesticides is not allowed unless they have been previously registered and labelled. However, there are gaps in regulation regarding the on-line sale of pesticides that could lead to environmental pollution or risks to human safety (Van den Berg et al. 2020).

The process of data evaluation, approval and registration of pesticides is rigorous and thus expensive and time-consuming. While high-income countries can afford this registration process, low-income countries cannot afford its implementation due to a lack of trained staff and government guidelines (Van den Berg et al. 2020). FIFRA requests that the EPA re-register older pesticides based on emerging data to be in line with current regulatory and scientific standards. It is also noted that pesticides produced solely for export do not need registration (Schierow 2013), which highly worryingly means that unregulated pesticides circulate globally. In the EU, prohibited pesticides can also be exported, if they follow the Rotterdam convention rules. International harmonisation of pesticide regulation is overseen by the Organisation for Economic Co-operation and Development (OECD) and its members to harmonise testing methods and data agreements. This allows manufacturers to register a pesticide in a number of countries with the same registration dossier, thereby saving time and money (Handford et al. 2015). However, pesticide registration has another obstacle that prohibits the sharing of information and data. For instance, certain data may be protected as trade secrets, and separate registrants may not use this same data to endorse registration applications for similar pesticides for a 10 year period (Schierow 2013).

When a pesticide is registered for use on a commodity or on a food item in the USA, the EPA establishes MRLs or alternatively grants an exemption from the need to provide a MRL based on the risk assessment data when it is determined to be safe. When no US registration is in place, interested parties may submit a petition requesting that the EPA establishes an import tolerance (or tolerance exemption) for a pesticide residue in a food or feed commodity. This rule permits food or feed treated with an unregistered (in the USA) pesticide in foreign countries to be legally imported into the US. The term “import tolerance” refers to a tolerance that exists in the USA for which there is no US registration in place, but that is in line with the US food safety standards (EPA 2015). The FAO has recently created a web-based toolkit to enhance the effectiveness and safety of pesticide registration at the domestic level, specifically in low- and middle-income countries. This toolkit integrates risk assessment data from the countries where the pesticides originate (Van den Berg et al. 2020).

Comparison of MRL Definitions

MRLs coalesce two types of information, one in the extent of regulatory coverage of the pesticides and the other the regulated residue levels (Dou et al. 2015). Table 1 indicates the various sources of data related to pesticide MRLs globally. Codex MRLs are international standards. While national MRLs can also be in place in countries, the national MRLs definition may demonstrate gaps with the Codex MRLs definition, especially on the Good Agricultural Practice (Table 2).

Table 1 Pesticide MRL Databases globally
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Impact of MRLs on Trade

Stringent MRLs have an impact on commodities being traded and can be perceived as protectionism and unfair competition. For instance, US exports are adversely affected by greater stringency in some destination markets. Canada's stringent MRLs allow its exports of plant and animal products and without impediments from MRL stringency in destination markets. Canada's imports are not influenced by either its own or its trading partners' MRL stringency (Xiong and Beghin 2016). Strict MRLs have an impact on trade regarding products from China as well. Stakeholders have advanced policy suggestions for lowering pesticide residues in China's primary agricultural products (Liu and Guo 2019). The growing concerns of international importers need to be addressed by planning and implementing relevant policies in order to ensure medium to long-term economic development (Dou et al. 2015), standardise management procedures and establish a food safety legal system that will be compatible with international standards (Li and Xu 2011). According to Dou, a major barrier to Chinese vegetable exports is due to extensive use of many types of pesticides in China, the rising number of regulated pesticides in importing markets, rather than the rising stringency of MRL levels (Dou et al. 2015).

With regard to control measures, the application of GAP was observed to be the most valuable control measure to guarantee the safety of fresh produce, followed by the implementation of good hygienic practices (GHP) and the accreditation of food safety management systems (FSMS) (Van Boxstael et al. 2013). In Liu & Guo's study of Chinese food exports that were linked to RASFF alerts for exceeding pesticide residue limits in agricultural products, a series of actions were taken against 244 illegal food products. This resulted in sanctions such as destruction of the food (36 products), withdrawal or recall from the market (22 products), official detention (36 products), sending back to the origin (42 products), declared them as imported products with no authorisation (43 products) and informing the public. In this case, the exceeding of MRLs on exported food products has had an impact on trade, a negative impact on business and a loss of revenue for producers (Liu and Guo 2019).

A Case Study on Rice

The Global Production of Rice

Rice is a food crop consumed as a staple food in many developing countries. Global rice production reached 502.94 million tonnes in 2019–2020 and its production is predicted to expand by 1% in 2021 as well as its utilisation (AMIS 2021). Rice production occurs in many parts of the world with the main producers located in Asia and sharing 90.14% of the production (Figs. 3 and 4). China, India, Indonesia, Bangladesh and Vietnam dominate the global rice market (Fig. 4). There are 2 major types of rice cultivated Oryza sativa (with the subspecies japonica and indica) or Asian Rice and Oryza glaberrima or African rice. Oryza sativa is cultivated in many places; however, Oryza glaberrima is exclusively farmed in Africa. Even though Oryza glaberrima has some advantages such as tolerance of weeds, resistance to pests or fast maturating growth, Oryza sativa has the advantage of offering a higher rate of productivity (FAOSTAT 2006).

Fig. 3
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Production share of rice paddy by region (FAOSTAT 2021a, b.)

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Fig. 4
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Top ten countries producing rice paddy in 2019 (FAOSTAT 2021a, b)

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Europe produces only 0.57% of the global rice crop. The type of rice produced by the EU niche market includes Oryza sativa subspecies japonica rice, the European rice (which accounts for 75% of the EU rice production and is mainly consumed in Southern Europe) and Oryza sativa subspecies indica (which represents 25% of EU rice production and is consumed in Northern Europe). Although the EU shows self-sufficiency for Oryza sativa subspecies japonica rice, it is not self-sufficient for Oryza sativa subspecies indica and needs to import this rice. India, Vietnam and Thailand are the top three exporting countries in the world. India leads with 36% of the export volume of rice worldwide, the second largest exporter is Vietnam with 15%, followed by Thailand at 14.5% in 2020/2021 (FAOSTAT 2021a, b) (Fig. 5). In 2019, the Republic of Korea had the highest import volume. The UK was the second highest country importing rice, followed by several EU member states (Fig. 6).

Fig. 5
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Top 10 countries in 2019 exporting countries of rice paddy (milled eq) (FAOSTAT 2021a, b)

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Fig. 6
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Top countries importers of quantity husked rice (FAOSTAT 2021a, b)

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Since the following listed countries are the main players in the global rice market; China and India (the main rice producers); India, Thailand and US (the main rice exporting countries) and Korea and EU (the importing countries), the MRLs of these countries for the four pesticide residues (Tricyclazole, carbendazim, thiamethoxam and acephate) will be compared due to their importance and the presence in rice.

Rice Classification and MRLs

Pesticides are used in the global agricultural system, on many fruits and vegetables, all field crops, and animal products and might affect the quality of unprocessed and processed food products. The EFSA 2019 report shows that 8.2% of the unprocessed rice samples and 12.2% of the rice-based processed samples were detected with pesticide residues above the MRL level (Cabrera and Pastor 2021).

Rice is a complex food, and the following terminologies are used to illustrate its various processing stages: in the husk (paddy or rough), husked (brown) rice, wholly milled or semi milled rice, polished or glazed rice and broken rice (Classifying rice). The consequence of these complexities is the occurrence and the distribution of the pesticide residues in paddy rice gathered and processed to brown rice, white rice, and rice bran. The pesticide residues are distributed differently depending on the processing stages of the rice. The levels of pesticide residues detected in paddy rice is more than in brown rice, but less in rice bran. This is due to the physico-chemical properties of rice and the lipophilic pesticides found in brown rice (Pareja et al. 2012). The complexities of rice create obstacles in the application of analytical methods for pesticide residues. However, there are limited studies that have focused on primary processing that have addressed the setting of precise values applicable for the processing factors (Pareja et al. 2011). In addition, pesticide distribution also varies according to the type of pesticide. Thiamethoxam and chlorantraniliprole are widely used for controlling pests in rice and are sometimes detected in rice hull, bran and polished rice grains, although their residues are greater in the hull and in rice bran (Teló et al. 2015). Fungicides like isoprothiolane, carbendazim, tricyclazole or tebuconazole are found more frequently and at high concentrations in paddy rice and at lower concentrations in white rice (Pareja et al. 2012).

Rice requires a range of labels according to the processing stage of the commodity and the type of rice. Codex MRLs use the terms of “rice, paddy rice/husked, brown rice/cargo rice, milled rice”, EU MRLS use the “Rice” label but the classification of rice in Fig. 7 presents a larger variation in the type of classified rice. US MRLs use ‘rice, rice bran, wild rice’. Canada uses the labels ‘rice, rice bran’ in its MRLs. In a short comparison of MRLs in rice (Table 2), the classification shows that the description and the label of the commodity is variable according to different countries.

Fig. 7
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Rice classification in the EU

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Table 2 National MRLs aligned with the definition of the Codex MRLs
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Pesticides in Rice

While most rice is imported into Europe, Southern Europe is a rice producing region, which includes Portugal, Italy, Spain, France, and Greece. The list of pesticides used in rice within the EU varies from one-member state to another (for example France and Italy have, respectively, 15 and 18 licensed compounds). India, one of the biggest suppliers of rice has a list of 87 substances used in the cultivation of rice (Eurlpesticides Resources and Information). Among these pesticides, acephate, tricyclazole, carbendazim and thiamethoxam are banned in the EU. In developing countries such as India, which have established their own pesticide regulatory systems, the use of highly dangerous pesticides remains due to insufficient or poorly enforced legislation (Handford et al. 2015). As per the governmental agency, all of them are used in India (FSSAI 2021).

The European Commission's Rapid Alert System for Food and Feed (RASFF) reports on phytosanitary controls performed on imported food items to verify that they were safe and did not contain banned compounds or unauthorised substances above the MRLs.

Tricyclazole, carbendazim, thiamethoxam and acephate have received the highest numbers of RASFF notifications and alerts due to their presence in rice (Fig. 8). The next section will focus on these four EU unauthorised pesticides.

  • Tricyclazole

    Tricyclazole (8-methyl-[1,2,4]triazolo[3,4-b][1,3]benzothiazole) is a fungicide that is widely used in rice cultivation around the world. Human exposure to this compound might occur via both dietary and non-dietary routes. Tricyclazole is currently not authorised in the EU, and the de facto EU MRL is 0.01 mg/kg of a product. The regulation (EC) No 396/2005 harmonises pesticide residue MRLs across the EU for all foodstuffs. As noted above, the existing MRLs can be modified to accommodate trade and before importation of produce, especially when the imported produce with residues may exceed national MRLs (Gov.UK 2021). The process to obtain a modification of an existing MRL requires data and an evaluation in order to perform a risk assessment and to conclude the toxicology of the substance at a higher MRL level. However, as an example, in 2013, Italy defined an import tolerance for tricyclazole in rice to facilitate authorised use of this pesticide in Brazil. This request was submitted by Dow AgroSciences LLC. The EU MRL for tricyclazole in rice at this time was established at 1 mg/kg in rice. As tricyclazole lost its authorisation, the EU authorities decided to lower its MRL to the LOQ (limit of quantification). As data regarding human health safety were not sufficiently robust to allow any MRL modification, the European Commission and EFSA denied its application (EFSA 2013).This case illustrates that gaps in data science on human health impacts or unclear legislation regarding harmful substance can be a tentative open door to change MRLs for the benefit of profits and trade. Harmonization is a necessity as low-income countries are facing challenges with their export products when their own MRLs are not aligned with the importing countries, or when national MRLs, and EU MRLs vary from Codex MRLs.

  • Carbendazim

    Carbendazim, a fungicide that is often detected in food substance, was banned in 2014 by the EU. Not only this, it is also prohibited in the UK, Morocco and Switzerland. The MRL of 0.01 mg/kg is used as de facto standard. Carbendazim and thiophanate-methyl are frequently grouped together as thiophanate-methyl, the parent compound, which is converted to carbendazim. Surprisingly, the use of thiophanate-methyl was not banned in agriculture. Unfortunately, it is impossible to know whether farmers use carbendazim or the parent compound. Carbendazim is not authorised in the EU, although it is legal elsewhere, and therefore its residues can be imported through food while aligning with the de facto national MRLs. According to EFSA, the MRLs were exceeded in 23 samples from the EU, indicating that this fungicide may still be used even in Europe and 91 samples from third countries (Cabrera and Pastor 2021). For example, carbendazim was found in 20 rice samples, mainly originating from India and Pakistan.

  • Thiamethoxam

    Thiamethoxam is a systemic pesticide, which means that it is transported throughout the plant from roots to leaves, flowers, nectar and pollen. The active substance is a neonicotinoid and chemically similar to nicotine. The use of thiamethoxam was prohibited in the EU in 2013 to protect bees (EFSA Aug 2021). Despite being withdrawn and banned, this compound is subject to emergency authorisation granted for plant protection products in member states in the EU (EFSA June 2018). Such sudden twists and turns reveal the discrepancy in pesticide legislation.

  • Case of Mixed Pesticides: Acephate and Thiamethoxam

    For all foodstuffs, the EU Regulations (EC 396/2005) harmonised MRLs on single pesticide across the continent. As several pesticides may be applied on crops, the impact and the synergies of mixtures of these pesticides are not assessed by regulators. As an example, acephate, an organophosphate pesticide, is banned in the EU but used in other countries for rice cultivation. The efficiency might increase when used in combination with other pesticides, but it appears to be harmful to the environment. For example, the combination of thiamethoxam and acephate was reported to have an impact on environment of the rice ecosystem in particular on Trichogramma Chilonis (T.Chilonis) wasps. They can successfully control Lepidopteran pests, attacking rice by parasitising their eggs. Thiamethoxam and acephate have different levels of toxicity; among them, the former has been found to be highly toxic for the parasitoids. Whereas the latter shows a lower toxicity but is still a threat to T. Chilonis (Preetha et al. 2009; Tang et al. 2017). According to Preetha and her colleagues, the use of these pesticides should be avoided in the rice ecosystem. According to the processing level of the rice, acephate degrades with a loss of 86% from rough brown rice to polished rice. Home processing removed 83.9% of acephate from polished to cooked rice. During storage at 25 °C, ambient temperature, acephate dissipated rapidly in the first two weeks to reach a level of 56.9% of the initial level of residue and then continued to degrade slowly. Considering its contact nature, after washing rice with tap water for 5, 15 and 30 min, the level of acephate was reduced by 9.8%, 15.7% and 35.3%, respectively. By adding soda to the washing solution and extending the length of the washing time, it can efficiently eliminate the contamination levels of the compound in rice. It demonstrated poor stability in alkaline solutions (Kong et al. 2012).

Fig. 8
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Number of EU RASFF Alerts for pesticides in rice from 01 January 2015 until 31 December 2020 (EU 2021). Data from FOODAKAI, the food risk prediction platform, Agroknow (FOODAKAI 2021)

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MRLs in Rice

Table 3 provides examples of MRLs established for the four selected pesticides, which are not authorised in the EU but are still being used in developing countries for rice cultivation, to highlight the differences between countries.

  • The EU MRLs are more stringent than the Codex MRLs, which were intended to facilitate trade and protect consumer health. The concern is whether the Codex MRL values are sufficiently protective of consumer health or only protective of trade.

  • For each of the pesticides, the MRLs show great variability compared to Codex MRLs. The US and Japan have the highest MRLs for tricyclazole, while the Codex has the highest MRL for carbendazim and acephate.

  • Indian MRLs are aligned with the Codex MRLs for carbendazim and acephate.

  • Tricyclazole MRLs are not mentioned in the Canadian and Codex MRLs and Thiamethoxam is not mentioned in the Codex MRLs. In addition, Codex MRLs are provided for pesticides used solely while some countries provide MRLs of a mixture.

  • Rice MRLs are linked to the processing stage of rice. The table shows MRL values for rice, brown rice and husk

  • Pesticides such as carbendazim and acephate are not used in the same form in some countries.

Table 3 Rice maximum residue limits for four EU unauthorized pesticides and used in rice culture in different global regions (MRLs, sources of data found in Table 1)
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Global differences in pesticide regulation highlight problems in trade, especially when developing countries use unauthorised pesticides or when MRLs are not in agreement (Handford et al. 2015).

Impact of Different Standards for Human Health, Trade and the Economies of Various Countries

The EU Pesticide Regulation (EC 1107/2009) is recognised as being the most stringent in the world, Codex MRLs are higher than the EU MRLs in most cases. This could raise doubts about whether the Codex MRLS are sufficiently protective of the health and the safety of the consumer or arguably that the EU limits are more based on restricting trade. Furthermore, exporting countries must comply with the standards of the importing country by monitoring their farming practices, enforcing controls and performing residue testing before export, consequently incurring additional costs to maintain trade.

The gaps in legislation in many low-income countries, where the systems of regulatory control and management of pesticides in agriculture are relatively poor, will have consequences for the protection of human health and the environment. It is necessary to prioritise the measures and make improvements in pesticide management practices in order to reduce pesticide use and minimise residues in food (Van den Berg et al. 2020). MRLs are poorly harmonised in many countries and where there is no compliance with even the Codex MRLs, it must point towards additional food safety risks. There are many discrepancies in the adoption of Good Agricultural Practices or information regarding National GAP. As defined by FAO, GAP is a “collection of principles to apply for on-farm production and post-production processes, resulting in safe and healthy food and non-food agricultural products, while taking into account economic, social and environmental sustainability.” Countries who have not adopted GAP or have their own country specific GAP might have health and safety issues. It is also worth highlighting that the influence of climate change may pose many new challenges in GAP, the use of pesticides and their efficacy and current GAP may not be suitable for the future (Miraglia et al. 2009).

Furthermore, the MRL value is based on a single pesticide. Regulations do not consider the synergistic effect that may occur among the multiple pesticides present in food. In addition, the Acceptable Daily Intake (ADI), which is an estimation of the amount of a pesticide in food, does not consider all the various pesticides present in it. Both parameters might have an impact on human health. However, in order to protect human health and vulnerable or at-risk people, the Food Quality Protection Act (FQPA) is applicable in the USA requires cumulative exposure assessment for classes of chemicals with common modes of Action. This cumulative risk assessment will allow the US Environmental Protection Agency (EPA) to approve pesticide tolerances. The tolerances need to be considered not only for food exposures but also exposures across drinking water and residential uses (Reeves et al. 2019). The tolerances may be adjusted for vulnerable people by a factor of 10 in order to protect this population (Reeves et al. 2019) and this may have an impact on trade.

In the EU, EFSA has developed methods to conduct cumulative risk assessment (CRA) of pesticide residues in food especially when mixture of pesticides is used on crops (EFSA Apr. 2020). Countries which prohibited the use of some highly toxic pesticides are still applying a MRL for imported product “import tolerance” and are trading with countries which are still using these banned pesticides in the import countries. The implementation of import tolerances does not require the complete data as those needed to register pesticides used in the US, such as farmer exposures, residual exposures, or environmental risks (EPA 2021).

Detection Methods used for Pesticides

Pesticide residue monitoring programmes in food are established by governments to ensure that products sold nationally or internationally are safe for consumption. These programmes involve taking samples of food and analysing them for pesticide residues on an annual basis. Nonetheless, the number of samples analysed varies considerably from country to country (Cabrera and Pastor 2021), and the analysis of food products seems to be more important when countries rely on their imports.

Pesticide testing is usually performed in two phases: sample preparation and analytical instrumentation testing. Some of the preparation methods such as QuEChERs (Quick, Easy, Cheap, Effective, Rugged and Safe) are favoured by most analytical scientists. Gas chromatography-mass spectrophotometry (GC–MS) and high performance-liquid chromatography (HPLC)–mass spectrometry (LC–MS/MS) are still widely used, regardless of the emergence of newer technologies such as capillary electrophoresis (CE) (Leong et al. 2020).

In the US, EPA approves tolerance levels and ensures analytical methods for monitoring pesticides in food. The FDA will enforce these tolerances and the USDA shares the results of the monitoring with FDA. The monitoring covers more than 800 pesticides including those were not approved in the USA, but may be present in imported commodities (Reeves et al. 2019). As the main rice production countries China and India must perform monitoring to meet the MRLs requirements of the importing countries. China, as the most important global user of pesticides in its agriculture, must bring its standards in line by regulating the number of pesticides used and applying MRLS, by developing standard methods of analysis for pesticide residues across the country and develop harmonisation between national, industrial and local standards (Liu and Guo 2019).

Conclusions

Pesticides are substances that are widely used to control pests in agriculture. Pesticide residues refer to the pesticides that remain on or in food after they are applied to food crops. The objective of this systematic review was to perform an in-depth analysis of pesticide legislation, focusing on rice, to understand the gaps that exist in the harmonisation across different countries. Pesticides were assessed regarding their utilization in agriculture and legislation surrounding their use. Existing gaps in pesticide regulations were considered. As a case study, the focus was one of the most important global crops, namely rice, to highlight these challenges and legislative gaps. This revealed some important gaps in harmonisation across different countries. The ultimate impact of these gaps will be on efficient use of pesticides, food security, food safety, environmental pollution and international trade. As Codex MRLs are international standards, this review shows that national MRL definitions are not always aligned with the definitions of the Codex MRLs and furthermore, there are no national MRLs or Codex MRLs for certain pesticides. The absence of MRLs at the Codex level as well as the value of Codex MRLs compared to more stringent national MRLs could raise concern regarding the pesticides in question. Non-registered pesticides or banned pesticides in developed countries are found in imported commodities from developing countries due to their exportation by these latter countries and their return in imported commodities. In trade, MRLs apply to these banned pesticides when zero tolerance is applied at a national level. However, the EU commission has recently promised that the legislation may be amended in the future and that banned pesticides in EU would not be produced for export.

MRLs are determined solely for the presence of a single pesticide in food product while mixed pesticides are present in food products with a possible synergistic effect that should be much better understood. Furthermore, countries may opt to use identical pesticides, a mixture of pesticides or other pesticides (mixed pesticides). The observation of four important pesticide residues in rice and the corresponding MRL values lack harmonisation. None of the Codex MRLs for the pesticides has a corresponding level in the US. While the US and Japan have the highest MRLs for tricyclazole compared to the Codex MRLs, the Codex has the highest MRLs for carbendazim and acephate compared to the EU. The EU MRLs are more stringent than the Codex MRLs which are claimed to protect consumer health. The concern is whether the Codex MRL values are sufficiently protective of consumer health or are more focused on international trade. The absence of Codex MRLs for some pesticides is a concern, especially with low-income countries lacking national legislation on pesticides.

Analytical methods vary from a country to another, which results in a lack of mutual recognition of exporting and importing countries. Similarly, there are variations in the number of samples tested in residue control programmes. With the aim of responding to the UAPP global situation among farmers and farm workers, countries at a national and international level will need to urgently improve pesticide use policies and health and safety preventive programmes. The level of farmers’ education regarding pesticide use and protection should be emphasised, particularly as climate change will impact pesticides activity and efficiency. Tolerances should consider the vulnerability of consumer groups as well as the exposures across diets, drinking water and residential uses. The discrepancies between developed countries and developing countries regarding the establishment of standards, reinforcement of policies, the impact of trade on the use of banned pesticides demonstrate gaps in worldwide harmonisation. As UAPP increase drastically among farmers and workforce, the cause of the trade of unauthorised pesticides in third countries needs to be explored and the practise make much more difficult to undertake.

This systematic review has highlighted that, for the most part, international pesticide regulations have been implemented to protect consumer health, the environment and facilitate international trade. However, the absence of national MRLs in some countries or non-alignments with Codex MRLs raise significant concerns regarding some pesticides in relation to the protection of consumer health and the use of mixtures versus single pesticides. Additionally, global differences in pesticide regulation highlight problems in trade, especially when developing countries use unauthorised pesticides or when MRLs are not in agreement. Therefore there is still much work to be done to harmonise the regulations globally, a major issue which should be at the forefront of dialogue between governments, regulators, NGOs and other stakeholders.