Quantitative assessment of mesothelioma and lung cancer risk based on Phase Contrast Microscopy (PCM) estimates of fibre exposure: an update of 2000 asbestos cohort data.

An earlier meta-analysis of mortality studies of asbestos-exposed worker populations, quantified excess mesothelioma and lung cancer risks in relation to cumulative exposure to the three main commercial asbestos types. The aim of this paper was to update these analyses incorporating new data based on increased follow-up of studies previously included, as well as studies of worker populations exposed predominantly to single fibre types published since the original analysis. Mesothelioma as a percentage of expected mortality due to all causes of death, percentage excess lung cancer and mean cumulative exposure were abstracted from available mortality studies of workers exposed predominantly to single asbestos types. Average excess mesothelioma and lung cancer per unit of cumulative exposure were summarised for groupings of studies by fibre type; models for pleural and peritoneal mesothelioma risk and lung cancer risk in terms of cumulative exposure for the different fibre types were fitted using Poisson regression. The average mesothelioma risks (per cent of total expected mortality) per unit cumulative exposure (f/cc.yr), RM, were 0.51 for crocidolite, 0.12 for amosite, and 0.03 for the Libby mixed amphiboles cohort. Significant heterogeneity was present for cohorts classed as chrysotile, with RM values of 0.01 for chrysotile textiles cohorts and 0.0011 for other chrysotile-exposed cohorts. Average percentage excess lung cancer risks per unit cumulative exposure, RL, were 4.3 for crocidolite and amosite combined, 0.82 for Libby. Very significant heterogeneity was present for chrysotile-exposed cohorts with RL values spanning two orders of magnitude from 0.053 for the Balangero mine to 4.8 for the South Carolina textiles cohort. Best fitting models suggest a non-linear exposure-response in which the peritoneal mesothelioma risk is proportional to approximately the square of cumulative exposure. Pleural mesothelioma and lung cancer risk were proportion to powers of cumulative exposure slightly less than one and slightly higher than one respectively.

Elongate mineral particles (EMP) characteristics and mesothelioma: Summary and resolution for session I of the Monticello II conference.

The summary contains a consensus opinion regarding the current state of the science about the dimensions of Elongate Mineral Particles (EMPs) as a factor impacting their carcinogenicity.

Lifetime occupational exposures and chronic obstructive pulmonary disease risk in the UK Biobank cohort.

BACKGROUND AND AIM: Occupational exposures are important, preventable causes of COPD. We previously found an increased risk of COPD among six occupations by analysing lifetime job histories and lung function data in the population-based UK Biobank cohort. We aimed to build on these findings and elucidate the underlying potential causal agents to focus preventive strategies. METHODS: We applied the ALOHA+job exposure matrix (JEM) based on the International Standard Classification of Occupations V.1988 codes, where exposure to 12 selected agents was rated as 0 (no exposure), 1 (low) or 2 (high). COPD was spirometrically defined as FEV1/FVC less than the lower limit of normal. We calculated semiquantitative cumulative exposure estimates for each agent by multiplying the duration of exposure and squared intensity. Prevalence ratio (PR) and 95% CI for COPD were estimated using robust Poisson regression adjusted for centre, sex, age, smoking and coexposure to JEM agents. Only associations confirmed among never-smokers and never-asthmatics were considered reliable. RESULTS: Out of 116 375 participants with complete job histories, 94 514 had acceptable/repeatable spirometry and smoking data and were included in the analysis. Pesticide exposure showed increased risk of COPD for ever exposure (PR=1.13, 95% CI 1.01 to 1.28) and high cumulative exposure (PR=1.32, 95% CI 1.12 to 1.56), with positive exposure-response trends (p trend=0.004), which were confirmed among never-smokers (p trend=0.005) and never-asthmatics (p trend=0.001). CONCLUSION: In a large population-based study, occupational exposure to pesticides was associated with risk of COPD. Focused preventive strategies for workers exposed to pesticides can prevent the associated COPD burden.

Laboratory study of the effectiveness of substituting traditional wheat flour with low dust flour and use of different sieve designs as controls to reduce exposure to inhalable flour dust in commercial bakeries.

Exposure to flour dust remains one of the leading causes of occupational asthma in Great Britain (GB). The average annual incidence rate per 100,000 bakers and flour confectioners in GB was 47.8 for the 3 yr period 2017 to 2019 compared with 0.53 for all occupations. There are many processes in commercial bakeries that can cause exposure to flour dust. Exposures are typically controlled by using local exhaust ventilation or respiratory protective equipment. The aim of this study was to evaluate the potential to reduce exposure to inhalable flour dust in commercial bakeries by modification of the process by use of a conical sieve in place of a round sieve; and substitution of traditional wheat flour (TWF) with 'low dust' flours LD1 and LD2 for dusting surfaces. Two simulated commercial bakery tasks were performed in a laboratory whilst dust exposures were measured in the breathing zone of the operator using an Institute of Occupational Medicine (IOM) sampler, button sampler and a real-time direct reading monitor. Analysis of variance tests were used to assess whether differences in mean exposures were statistically significant with the different control approaches. A qualitative visual exposure assessment was also undertaken using Tyndall illumination. Substituting TWF with LD1 and LD2 reduced exposure to inhalable flour dust by 86% and 53% respectively when sieving and by 78% and 67% respectively when filling a hopper. There was no statistically significant difference between dust emissions for all 3 flours when using the conical sieve instead of the round sieve for flour dusting tasks. This laboratory study has shown that substituting TWF with low-dust flour may reduce inhalable dust exposures when dusting surfaces in bakeries.