Assessment of the future mesothelioma disease burden from past exposure to asbestos in ship recycling yards in India

Our plain-English summary of Assessment of the future mesothelioma disease burden from past exposure to asbestos in ship recycling yards in India, by R. Singh, J.W. Cherrie, B. Rao, et al (International Journal of Hygiene and Environmental Health, 2020).

The study

• Authors: R. Singh, J.W. Cherrie, B. Rao, S.R. Asolekar
• Journal: International Journal of Hygiene and Environmental Health
• Published: 2020;225:113478
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The recycling of end-of-life vessels is a complex activity that generates an enormous amount of hazardous waste, including asbestos-containing materials (ACM). Efforts by the Government of India to comply with national and international regulations and improved standard operating procedures are expected to lower the exposure risk of the workforce to hazardous substances, including asbestos. The current workers are likely to face lesser risks than did those exposed in the past. The present study assesses the health risks from past exposure of asbestos for those workers engaged in handling and removing ACM in ship recycling yards before environmentally sound recycling of obsolete ships was introduced in the early 2000s. Estimates were made of the number of workers exposed, and the intensity of exposure and these data were used to estimate the likely number of mesothelioma deaths in the future. It was estimated that nearly 15% of the total workforce engaged in ship recycling will suffer from mesothelioma which translates to about 4,513 mesothelioma deaths among the total of 31,000 workers estimated to be ever employed in the yards from 1994 till 2002. Recommendations are made for a practical approach to the safe handling of ACMs in Indian ship recycling yards.

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In plain English

This was a modelling study, not a count of actual cases. The authors estimated future mesothelioma deaths among workers at the Alang-Sosiya ship recycling yards in Gujarat, India, from asbestos exposure before working conditions improved. Using a published method that builds exposure estimates from descriptions of the work, they assumed ships contained chrysotile and amosite. They estimated average exposures for workers handling asbestos materials of 103 fibres/ml (engine and boiler rooms), 320 fibres/ml (accommodation areas such as doors) and 42 fibres/ml (other materials). Bystander levels were 23, 140 and 1.1 fibres/ml. The authors estimated that 30,100 workers were employed in the yards from 1982 to 2002. They modelled risk from exposure during 1994 to 2002 using the Berman and Crump risk model, and predicted 4,515 mesothelioma deaths over the whole period, nearly 15% of the workers employed in 1994. Of these, 1494 were among workers directly handling asbestos and 3021 among bystanders. Deaths were predicted to peak in 2027. Worker ages and employment dates were unknown and were assumed. The authors stated the toll might be underestimated, and that smoking was not considered.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Modelling risk assessment: exposure estimated from published descriptions of the work (Cherrie et al. 2018 method), then mesothelioma deaths predicted with the Berman and Crump (2008) risk model; no workers were examined or measured
• Who was studied: Workers at the Alang-Sosiya ship recycling yards, Gujarat, India. The authors estimated 30,100 workers were employed from 1982 to 2002, based on the number of ships recycled. Risk analysis covered exposure during the 1994 to 2002 period. Workers were assumed to be uniformly aged 19 to 45, with 30% working directly on asbestos-containing materials (near-field) and 70% exposed indirectly as bystanders (far-field).
• Exposure: Asbestos released while removing asbestos-containing materials during ship dismantling, in three activity groups: delagging in boiler and engine rooms, removal of acoustic doors in accommodation areas, and other asbestos materials. Ships were assumed to contain chrysotile and amosite, using an intrinsic emission of 3.5 fibres/mL.
• Main results:
  • Estimated average near-field exposure for workers doing the work: 103 fibres/ml (engine and boiler rooms), 320 fibres/ml (accommodation areas such as doors) and 42 fibres/ml (other asbestos materials)
  • Estimated far-field (bystander) exposure: 23 fibres/ml near engine and boiler rooms, 140 fibres/ml near accommodation-area demolition and 1.1 fibres/ml near other asbestos materials
  • Over the whole period, 4,515 mesothelioma deaths were predicted among the workforce, described as nearly 15% of the workers employed in 1994. The article gives 1841 as the number of total deaths estimated in 2017.
  • The year with the most predicted deaths was 2027, with a rapid increase in predicted deaths between 2012 and 2017
  • Predicted deaths were 3021 among bystanders (14% of the bystander population) and 1494 among those working directly with asbestos materials (nearly 16% of the near-field population)
• The authors' conclusion: The authors concluded it is likely that the mesothelioma death rate is nearly 15% in this group of highly exposed workers. They also concluded that deaths recorded in Indian cancer registries appear too low.
• Limitations the authors state:
  • Workers' gender, birth dates and employment dates were unknown, so these were estimated from assumptions
  • A uniform age distribution was assumed. If more workers were younger, the death burden might have been underestimated.
  • Risk was calculated only for 1994 to 2002, although operations began in 1982, which may also have underestimated the burden
  • Smoking and other mortality risk factors were not considered. If workers smoked more than the general population, mesothelioma risk could have been overestimated.
  • Lung cancer risk from the asbestos work was not estimated

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma, Shipyards and maritime work.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Asbestos-Containing Material (ACM).

Related studies

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• Radiological evidence of asbestos disease among ship repair workers — I.J. Selikoff, W.J. Nicholson, et al. (1980)
• Asbestos-related disease in Bangladeshi ship breakers: a pilot study — M.N. Courtice, P.A. Demers, et al. (2011)
• Mortality among dock-yard workers in Genoa, Italy — R. Puntoni, L. Russo, et al. (1977)
• Estimation of the past and future burden of mortality from mesothelioma in France — A.G. Ilg, J. Bignon, et al. (1998)

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