Impact of a modification of food regulation on cadmium exposure

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Highlights

  • 0.6% of the French population is overexposed to cadmium.

  • Main contributors to cadmium exposure are bread, bivalve mollusks and potatoes.

  • Applying new maximum limits would not dramatically reduce cadmium exposure among the population.

  • Acting on the level of contamination from environmental sources should be investigated to decrease cadmium exposure.

Abstract

The 2nd French Total Diet Study demonstrated that 0.6% of adults and 14.9% of children exceeded the tolerable weekly intake set by EFSA. The overexposure of several consumers (adults and children) can be partially due to the high consumption of bread and dried bread products, of bivalve mollusks and of potatoes. Except for mollusks, these foods are the main contributors identified for the general population. On this basis, the French agency for food, environmental and occupational health and safety (ANSES) assessed whether a decrease of the European maximum limits in foodstuffs could significantly reduce the level of exposure of French consumers. Applying ML set at P90 of the main contributors would neither significantly reduce exposure levels to cadmium for the general population, nor the percentage of subjects exceeding the TWI. To reduce background consumer exposure to cadmium, actions to be taken include efforts on sources that are at the origin of the soil contamination and the efficacy of consumption recommendations.

Introduction

Cadmium (Cd) is a widespread metallic trace element, naturally present in the environment but also found in high concentrations at certain sites as a result of human activities (metalworking, mines and other industries) and is of potential concern as a contaminant in the food chain.

Consequently, the European Union has passed and amended a series of Regulations on cadmium. These are based on setting maximum levels (ML) of cadmium in several foodstuffs (EU, 2006) and are, among others, 1 mg/kg fresh weight (fw) for mollusks, 0.2 mg/kg fw for bran and durum wheat and 0.1 mg/kg fw for flour. However, since EFSA lowered the health based guidance value (tolerable weekly intake or TWI) by a factor of almost three in 2009 (From 7 to 2.5 μg/kg bw/week, EFSA, 2009) and since new data became available concerning food contamination and the exposure and body burden of different population groups, the European Commission and the Member States have put in motion a revision of the ML for cadmium in foodstuffs.

In the adult population (between 18 and 74 years old) studied in the French biosurveillance study (ENNS) (Fréry et al., 2011) the mean and median concentrations of urine cadmium in France were both equal to 0.29 μg Cd/g creatinine, and the 95th percentile to 0.91 μg Cd/g creatinine. Those recent data for body burden suggest that 3.6% of French adults exceed the 1 μg Cd/g creatinine threshold of toxicological concern set by EFSA (EFSA, 2009). It is of importance to note that none of the subjects in the study exceeded the action threshold proposed by the German Human Biomonitoring Commission (5 μg Cd/g creatinine, Fréry et al., 2011).

These mean levels are in agreement with those found in France during previous investigations carried out by the French institute of surveillance (InVS) in 1997, 2000 and 2005 in different French cities (about 0.3 μg Cd/g creatinine at Salsigne and its surrounding area; RNSP, 1997) as well as in Marseilles (ORS PACA, 2011) and 0.27 μg Cd/g creatinine in the national study on incineration plants (Afssa, 2009).

Mean human urinary cadmium levels measured in the ENNS study were similar to those observed in the National Health and Nutrition Examination Survey (NHANES) carried out in 2003–2004 (CDC, 2009) on a representative sample of the population of the United States, in the Canadian Health Measures Survey performed in 2007–2009 (Health Canada, 2010) and in the population of the Czech Republic in 2005 (NIPH, 2006, NIPH, 2010). On the other hand, the levels observed in Germany in the adult population ten years ago were slightly lower (Becker et al., 2003): 1.5 times lower than the mean in the adult French population and 1.25 times lower at the 95th percentile.

In 2006, the French agency for food, environmental and occupational health and safety (ANSES) showed that high consumers of seafood (fish, mollusks and crustaceans) had a higher body burden than the national average, with mean cadmium levels of 0.65 μg Cd/g creatinine and 1.19 μg Cd/g creatinine at 95th percentile (Sirot et al., 2008). In this study, subjects over the age of 64 years had mean body burden of 0.95 μg Cd/g creatinine and 1.94 μg Cd/g creatinine at P95. Fifteen percent of subjects in the study had body burden exceeding the threshold of concern. On the other hand, none exceeded the level of 5 μg Cd/g creatinine.

In 2006, Anses launched the second French total diet study (TDS2) to assess the dietary exposure of the general population to 445 substances of public health interest, including cadmium. The TDS consisted in three major steps: (i) food sampling and sample preparation as consumed by the population, (ii) analysis of the samples, and (iii) dietary exposure assessment by combining the occurrence data with the national consumption data. The food sampling methodology has already been described in details elsewhere (Sirot et al., 2009) as well as results for the substances measured in the TDS (Nougadère et al., 2012, Bemrah et al., 2012, Sirot et al., 2012, Rivière et al., 2014, Sirot et al., 2012b). The results for trace elements (including cadmium) can also be found (Millour et al., 2011, Arnich et al., 2012). The French population's mean exposure to cadmium was estimated at 1.12 μg/kg bw/wk in adults (18–79 years old) and 1.68 μg/kg bw/wk in children (3–18 years old). At the 95th percentile, exposure was estimated at 1.89 μg/kg bw/wk in adults and 3.15 μg/kg bw/wk in children. The main contributors to cadmium exposure both in adults and children were bread and dried bread products (22% and 13%, respectively) and potatoes and potato products (12% and 14%, respectively). Detailed data show that adults with the highest estimated intakes are high consumers of mollusks and crustaceans, bread and potatoes. EFSA's TWI of 2.5 μg/kg bw/wk (EFSA, 2009) is exceeded by 0.6% [CI95% 0.3–1.0] of adults and by 14.9% [CI95% 13.0–16.7] of children.

The difference between the proportion of subjects exceeding the reference values set for body burden (3.6%) on one hand, and set for food consumption on the other (0.6%), can be explained, leaving aside methodological differences, by the fact that diet accounts for 90% of exposure of non-smokers (UNEP, 2008) and that part of the general population's body burden can be attributed to other contamination vectors (mainly tobacco). Moreover, body burden reflect past exposure, whereas TDS reflects current dietary exposure, and data suggest that cadmium concentrations in foods and exposure tend to decrease for several years (Béchaux et al., 2014).

Moreover, dietary exposure data suggest that 1.4% of adults are exposed to more than 90% of the TWI. For these individuals the exposure margin is low if other potential sources of cadmium are taken into account.

The results generated by these two approaches concur, emphasizing that a small part of the French adult population is over-exposed to cadmium, largely through dietary intake, and that high consumers of seafood appear to be more exposed than the general population. The level of overexposure remains moderate and it would be helpful to compare it to a future action threshold to decide on the most appropriate reduction measures to be taken.

As a small fraction of the French population is overexposed to cadmium and since foods are the main source of contamination (excluding smoking and occupational exposure), dietary regulations could be an effective way of reducing exposure. Since cadmium is a ubiquitous metal found in a large number of foods, it is important to identify the food groups to be regulated. The present work focuses on the evaluation of strategy that could help decreasing cadmium exposure of adults via foodstuffs. The impact on cadmium dietary exposure of new ML has been assessed as well as the impact on the percentage of individuals exceeding the TWI.

Section snippets

Consumption and exposure profiles

Exposure data used in the present work have already been described elsewhere (Arnich et al., 2012). Briefly, total individual exposures were assessed by combining consumption and contamination data. The national and individual food consumption survey (INCA2) was carried out in between December 2005 and May 2007 (Dubuisson et al., 2010). The survey included 2624 adults (aged 18–79), these random sample were drawn using a multistage cluster sampling technique. After exclusion of the

Results and discussion

The 5% of subjects exceeding the 95th percentile of exposure corresponded to a sample of 90 adults (35 men and 55 women), aged from 18 to 78 years old. Their consumption profile was not significantly different from that of the 0.6% of individuals exceeding the TWI. Their mean exposure (±standard deviation) was 2.24 ± 0.05 μg/kg b.w. per week. Their mean body weight (63 ± 11 kg) and mean body mass index (BMI) (22.2 ± 3.5 kg/m2) were significantly lower than those for the general adult population

Conclusions

The results of the second French total diet study emphasized the need to decrease cadmium exposure in the general population. This appeared in several EU countries (United Kingdom, Ireland …) since the lower health based guidance value was published by EFSA. The main sources of cadmium exposure being food (FSAI, 2011), setting maximum limits in highly contaminated food items could be an efficient way to decrease the general population exposure. In the present work, the impact of setting new ML

Acknowledgments

The authors acknowledge the members of the “physical and chemical contaminants in food” panel for their scientific contribution (J.C. Amiard, A. Periquet, P.M. Badot, A. Baert, V. Camel, M. Clauw, H. Coffigny, C. Feidt, F. Hommet, T. Guerin, B. Le Bizec, A.M. Le Bon, R. Maximilien (chair), J.F. Narbonne, I. Oswald, J. Rose, A.C. Roudot, J. Tulliez, P. Vasseur, J.P. Vernoux).

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    These authors equally contributed to this work.

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