New global indicator for workers’ health: mortality rate from diseases attributable to selected occupational risk factors

Abstract Through sustainable development goals 3 and 8 and other policies, countries have committed to protect and promote workers’ health by reducing the work-related burden of disease. To monitor progress on these commitments, indicators that capture the work-related burden of disease should be available for monitoring workers’ health and sustainable development. The World Health Organization and the International Labour Organization estimate that only 363 283 (19%) of 1 879 890 work-related deaths globally in 2016 were due to injuries, whereas 1 516 607 (81%) deaths were due to diseases. Most monitoring systems focusing on workers’ health or sustainable development, such as the global indicator framework for the sustainable development goals, include an indicator on the burden of occupational injuries. Few such systems, however, have an indicator on the burden of work-related diseases. To address this gap, we present a new global indicator: mortality rate from diseases attributable to selected occupational risk factors, by disease, risk factor, sex and age group. We outline the policy rationale of the indicator, describe its data sources and methods of calculation, and report and analyse the official indicator for 183 countries. We also provide examples of the use of the indicator in national workers’ health monitoring systems and highlight the indicator’s strengths and limitations. We conclude that integrating the new indicator into monitoring systems will provide more comprehensive and accurate surveillance of workers’ health, and allow harmonization across global, regional and national monitoring systems. Inequalities in workers’ health can be analysed and the evidence base can be improved towards more effective policy and systems on workers’ health.


Introduction
Countries have made policy commitments through the sustainable development goals (SDGs) to ensure health and promote decent work for all. 1 SDG targets 3.9 and 8.8 are to "substantially reduce the number of deaths and illnesses from hazardous chemicals and air, water and soil pollution and contamination" and "promote safe and secure working environments for all workers." Countries have committed to workers' health through the World Health Organization (WHO) Strategy on Health, Environment and Climate Change, 2 Pan American Health Organization Plan of Action on Workers' Health 2015-2025, 3 International Labour Standards on Occupational Safety and Health 4 and the International Labour Organization (ILO) framework of Fundamental Principles and Rights at Work. 5 Achieving these targets requires preventing exposure to occupational risk factors and reducing the burden of disease that is attributable to unhealthy and indecent working conditions.
To track progress, the work-related burden of disease must be monitored in global, regional and national systems for surveillance of workers' health and progress on sustainable development.
Health indicators are "summary measures that capture relevant information on different attributes and dimensions of health status." 3

Indicators of workers' health have received little
We sourced the denominator, total population of working age (≥ 15 years), from the United Nations' official population estimates: the 2019 Revision of World Population Prospects. 26

Calculation method
We calculated the total number of deaths from diseases attributable to selected occupational risk factors by summing the estimates for the 21 individual exposure-disease pairs (Table 1). We then divided this number of deaths by the total working-age population. We calculated the indicator for national, regional and global population cohorts by sex and age group, using the following formula: 100 000 D MR WP   (1) where MR is the mortality rate per 100 000 working˗age population [disease, occupational risk factor, country, sex, age], D is the number of deaths [disease, occupational risk factor, country, sex, age] and WP is the number of working˗age population [country, sex, age]. This calculation gave the final indicator: mortality rate per 100 000 working-age population from diseases attributable to selected occupational risk factors, by disease, risk factor, sex and age group. For each estimate, we calculated 95% uncertainty ranges (UR) using bootstrapping. 27 Applying the indicator

By region and country
In  Table 2). Regional mortality rates were lowest in the African Region (11.4 deaths per 100 000, 95% UR: 11.1 to 11.
For the African, Eastern Mediterranean, South-East Asia and Western Pacific Regions, the cardiovascular diseases group also contributed most to the mortality rate (Fig. 3). In contrast, work-related malignant neoplasms contributed most to the mortality rates in the Region of the Americas and European Region.

By occupational risk factor
The pattern of mortality rates by occupational risk factor corresponded to that by disease group, since these are linked in exposure-disease pairs (Table 1). 28 Exposure to long working hours contributed the largest proportion of deaths from work-related diseases (corresponding to cardiovascular diseases). Among the regions, long working hours accounted for the largest proportion of deaths in the African, Eastern Mediterranean, South-East Asia and Western Pacific Regions. However, in the Region of the Americas and European Region, occupational exposure to carcinogens (corresponding to malignant neoplasms) contributed the largest proportion of deaths.

By sex
Males had a higher global mortality rate attributed to work-related diseases (40.1 deaths per 100 000 working-age population; 95% UR: 38.6 to 41.5) than did females (15.3 deaths per 100 000; 95% UR: 14.6 to 16.0). 28 Mortality rates for work-related diseases were higher for males than females in all regions.

By age group
Global mortality rates from work-related diseases were higher in older people than in younger people, reflecting general patterns of noncommunicable disease. 29

National monitoring
In 2008-2009, national information systems for workers' health existed in 51 (42%) out of 121 of countries. 30 In Table 3 we present case studies from four countries across different regions, describing their current monitoring system for workers' health and showing how the new indicator could be integrated into national information systems. [31][32][33][34][35][36][37][38][39][40][41] We also suggest potential facilitators and barriers to the integration of the new indicator into national monitoring systems and its predicted impact. The case studies suggest that the new indicator would fill a gap in current monitoring systems and could serve as an addition rather than a replacement for existing indicators. Feedback from country respondents demonstrated that none of their monitoring systems include the new indicator (Table 3). Some countries already had similar indicators, calculated using national data sources and using various methods that limit international comparability of their indicators. For other countries, the indicator could not be calculated from currently available data.
Country respondents suggested potential benefits of the indicator that could facilitate its introduction into monitoring systems (Table 3). Benefits include providing additional information to evaluate the occupational disease burden, and generate greater awareness of emerging occupational diseases. The relevance and ready availability of the indicator in the Several potential positive impacts of the new indicator were mentioned (Table 3).
Country respondents suggested that the indicator could improve the monitoring of workers' health and strengthen the attribution of occupational and work-related diseases, thereby potentially improving coverage of workers' compensation and therefore the basic level of the social protection floor. The indicator could also promote awareness of occupational risk factors and work-related diseases among health policy-makers and foster action within the health and other sectors.
Next steps for countries could include adoption of the indicator into their national monitoring systems and promotion of the indicator among their networks, including national, regional and global authorities responsible for workers' health and sustainable development monitoring. Until countries are able to collect their own data for the number of work-related deaths they can use the WHO/ILO joint estimates, as presented in this article. Current estimates were published in September 2021, 10 but the indicator can be produced annually, using updates to the WHO estimates of the total number of deaths per disease 25 and population-attributable fractions for occupational risk factors. [10][11][12][13] The indicator is also available disaggregated by sex and age group for monitoring health inequalities among workers, 42 ensuring that no one is left behind in sustainable development. 1 Global and regional monitoring In Fig. 1 we show how the indicator is already being integrated into global and regional monitoring systems. At the global level, WHO is using the indicator in its environmental health monitoring system, 43

Strengths and weaknesses
The new indicator has several strengths. First, using the United Nations' established methods 9 and open-access data sources, 10,26 the indicator captures the great majority of the total estimated work-related deaths. [10][11][12][13] Second, as the number of work-related deaths (the numerator) is estimated based on modelling of exposure data and relative risks, these estimates are less at risk of misreporting bias than estimates based on reported or compensated cases of fatal occupational or work-related disease. Third, the indicator can also be used to monitor other health topics, such as the social and commercial determinants of health (as a proxy for exposure to unhealthy working conditions) and noncommunicable diseases (as the fraction of these diseases that can be addressed by health protection and promotion in workplaces and by whether the worker works in the informal or formal economy, but this would require disaggregated input data, which are currently sparse. 49,50 Finally, the quality of the indicator depends on the input data. Governments are encouraged to continue their work to provide largescale, high-quality, official data on individuals' exposure to occupational risk factors and on causes of death and disease.

Alternative specification
There are possible alternative specifications for the indicator. The data source for the numerator could be reported fatal or incident cases of occupational disease, or national occupational burden of diseases estimates, as already monitored in some countries (Table 3). Nevertheless, the advantage of using the WHO/ILO joint estimates is that they produce comparable estimates for 183 countries and the six WHO regions and their population cohorts. Alternatively, using disability-adjusted life-years attributable to occupational risk factors would capture both mortality and morbidity.
The use of total population as the denominator would facilitate comparisons with other mortality rate indicators that use the total population, such as those in the global indicator framework for the SDGs. 9 However, as the data for the numerator are collected for people aged 15 years and older, we believe that the working-age population is the most appropriate denominator for the indicator.

Conclusions
The workplace is an important setting for preventing disease. 51 A key first step when improving working conditions is understanding and quantifying the risk factors and their attributable burdens. With the current focus of monitoring on occupational injuries, the majority of workrelated mortality is not captured. To assess progress towards health targets for workers, international organizations, regions and countries must expand their indicators to consider mortality from work-related diseases. Integration of this new indicator in global, regional and national monitoring systems will improve the comprehensiveness, accuracy and harmonization of workers' health and sustainable development surveillance. The indicator will provide opportunities for analysing health inequalities among workers, both within and between countries. The indicator can provide an improved evidence base for developing effective health policy and systems for workers and can play a key role in assessing progress in countries' policy commitments to workers' health. [1][2][3][4][5] 42. Handbook on health inequality monitoring with a special focus on low-and middleincome countries. Occupational exposure to asbestos a Ovary cancer d 3 Occupational exposure to asbestos a Larynx cancer d 4 Occupational exposure to asbestos a Mesothelioma d 5 Occupational exposure to arsenic a Trachea, bronchus and lung cancers d 6 Occupational exposure to benzene a Leukaemia 7 Occupational exposure to beryllium a Trachea, bronchus and lung cancers d 8 Occupational exposure to cadmium a Trachea, bronchus and lung cancers d 9 Occupational exposure to chromium a Trachea, bronchus and lung cancers d 10 Occupational exposure to diesel engine exhaust a  The national workers' health monitoring system of China comprises the national surveillance system of occupational disease 31 and the national surveillance system for occupational hazards in the workplace. 32,33 The agency responsible for the former monitoring system is the Chinese Center for Disease Control and Prevention of the National Health Commission. The occupational disease surveillance system is the most relevant to the new indicator. It is a network-based reporting system that includes all relevant agencies in China. The system reports new cases of occupational disease covering a total of 121 diseases in nine categories and relevant variables such as age, job title, duration of work and industrial sector.
The relevant indicators in the national monitoring system are: (i) number of workers exposed to occupational risk factors (data collected in national statistical surveys); (ii) number of diagnosed cases of occupational disease (data collected by the Agency of Occupational Disease Diagnosis based on clinical diagnosis and the occupational exposure experience); and (iii) number of deaths due to occupational disease (data collected from the national mortality surveillance system).
The monitoring system does not include the new indicator.
The new indicator could be included in the national monitoring system without replacing any current indicators.
The new indicator could be calculated using number of deaths due to occupational disease as the numerator, obtained from national data sources. However, the national workers' health monitoring system can only collect the approximate number of deaths due to occupational disease, so only an approximate of the new indicator can be calculated.

Facilitators:
The new indicator can be used to better evaluate the burden of disease caused by occupational risk factors in China.

Barriers:
The variables needed to calculate the indicator from national data sources are still not accurate enough. The country therefore needs to develop a better evaluation method.