Changing trends in US mesothelioma incidence.

The correspondence by Weillet al (below) refers to a letter by Greenberg, which was published in February's edition of the journal. We regret the late appearance of this printed response, which arises from an administrative error. An electronic version of this text was posted on the website on 1 February 2005.

Mortality from lung and kidney disease in a cohort of North American industrial sand workers: an update.

Background: A previously published cohort study of some 2670 employees of the North American sand industry, followed through 1994, provided strong evidence of a causal relationship between quartz exposure and death from both silicosis and lung cancer, after allowance for cigarette smoking and in the absence of known occupational carcinogens. Unexpectedly, a significant excess mortality from chronic non-malignant renal disease [observed 16; expected 7.6; standardized mortality ratio (SMR) 212] was also found, whereas deaths from renal cancer at this stage were close to expectation (observed 6; expected 5.

Changing trends in US mesothelioma incidence.

Aims: To report the temporal pattern and change in trend of mesothelioma incidence in the United States since 1973.

Methods: The Surveillance, Epidemiology, and End Results (SEER) programme of the National Cancer Institute has since 1973 provided annual age adjusted incidence for mesothelioma in representative cancer registries dispersed throughout the USA. SEER data are analysed to describe the trend of male mesothelioma incidence in the USA.

Relationship of asthma to irritant gas exposures in pulp and paper mills.

The potential of chronic or acute irritant gas exposures to cause asthma or a variant condition, reactive airways dysfunction syndrome (RADS) was investigated by observing asthma incidence in a large working population, using person-years at risk (P-YR) to compute relative rates (RR). Health data came from employee examinations at 62 pulp and paper plants. The 39122 workers who denied asthma beginning before the observation period included: 19326 denying irritant exposures, with no gassing exposures; 19349 with self-reported irritant exposures, and no gassing; and 447 with documented gassings.

Cohort mortality study of North American industrial sand workers. III. Estimation of past and present exposures to respirable crystalline silica.

Background: Lung cancer and silicosis mortality were examined longitudinally and by a case-referent analysis in a cohort of workers selected from the North American industrial sand industry. Date of hire in the case-referent sub-cohort extended as far back as the second decade of the twentieth century.

Objective: The aim of this study component was to develop estimates of average and cumulative exposure to respirable crystalline silica for the 342 selected cases and referents.

Cohort mortality study of North American industrial sand workers. II. Case-referent analysis of lung cancer and silicosis deaths.

Background: A cohort mortality study of 2670 men in nine North American industrial sand plants resulted in 83 deaths from lung cancer 20 or more years after hire (standardized mortality ratio 139) and 37 deaths from silicosis (including seven from silico-tuberculosis). The lung cancer excess was unrelated to duration of employment and not found in all plants.

Objectives: The primary aim was to determine whether lung cancer risk among these employees was related to quantitative estimates of crystalline silica exposure, after allowance for cigarette smoking.

Cohort mortality study of North American industrial sand workers. I. Mortality from lung cancer, silicosis and other causes.

Background: In 1997 a Working Group of the International Agency for Research on Cancer changed an earlier classification of crystalline silica as a human carcinogen from Group 2A to Group 1, though commenting that the carcinogenicity might vary with industrial circumstances and depend on additional factors affecting biological activity, including the distribution of its polymorphs.

Objective: We aimed to determine whether pure quartz exposure uncomplicated by the presence of other contaminating carcinogens, as experienced by workers in the production of high-grade industrial sand, was causally related to an increased risk of lung cancer.

Methods: A cohort of 2670 men employed before 1980 for 3 years or more in one of nine North American sand-producing plants and a large associated office complex was selected for study.

Crystalline silica exposure, radiological silicosis, and lung cancer mortality in diatomaceous earth industry workers.

Background: The role of silicosis as either a necessary or incidental condition in silica associated lung cancer remains unresolved. To address this issue a cohort analysis of dose-response relations for crystalline silica and lung cancer mortality was conducted among diatomaceous earth workers classified according to the presence or absence of radiological silicosis.

Methods: Radiological silicosis was determined by median 1980 International Labour Organisation system readings of a panel of three "B" readers for 1809 of 2342 white male workers in a diatomaceous earth facility in California.

Radiographic evidence of silicosis risk in the diatomaceous earth industry.

There is limited and conflicting evidence regarding the exposure-response relationship between exposure to crystalline silica and silicosis; the level of risk to current workers remains uncertain. We conducted an epidemiologic investigation of 1,809 workers in the diatomaceous earth industry, where exposures to crystalline silica are primarily to the cristobalite form. On the basis of the median of three independent readings, 81 (4.

Dose-response associations of silica with nonmalignant respiratory disease and lung cancer mortality in the diatomaceous earth industry.

The potential carcinogenicity of crystalline silica to humans remains a controversial issue. The authors conducted an historical cohort mortality study of 2,342 male workers exposed to crystalline silica, predominantly cristobalite, in a diatomaceous earth mining and processing facility in California. During the years 1942-1994, mortality excesses were detected for nonmalignant respiratory diseases (NMRD) (standardized mortality ratio = 2.

Adjusting FVC for the effect of obstruction.

Objective: To derive a method of taking into account the effects of obstruction on the FVC, allowing more accurate assessment of other negative ("restrictive") influences.

Design: In 656 subjects with airways obstruction, defined as FEV1/FVC of 0.70 or less, regression of FVC was expressed as percentage of predicted value (FVC %PRED) on potential explanatory variables, including FEV1/FVC.

Blue-collar normative spirometric values for Caucasian and African-American men and women aged 18 to 65.

Normative spirometric values were derived from 5,042 white (of mainly European ancestry) and black (of mainly African ancestry) men and women paper plant workers who are never-smokers, with no respiratory symptoms or diagnoses and no history of occupational exposure to fibrogenic dusts or irritant chemicals. This cohort was selected from a much larger population under long-term respiratory surveillance (n > 50,000 at 50 plants). Standardized equipment, procedures, and data reduction methods complied with ATS recommendations.

Crystalline silica: risks and policy.

Since the International Agency for Research on Cancer labeled crystalline silica a probable carcinogen in 1988, government regulations have required sand and other products to contain warning labels and researchers have attempted to quantitatively assess low-exposure risks. The uncertainties are unlikely to diminish any time soon, and little value exists in calculating such risks, as low exposures to this ubiquitous mineral are commonplace in both urban and rural areas due to many uncontrollable activities. What is certain is that regulatory resources targeted at continuing high-level occupational exposures would be much more likely to have beneficial public health consequences than continued attempts to assess low-exposure risks quantitatively.

Biological effects: asbestos-cement manufacturing.

Fourteen cohorts of asbestos-cement workers have been studied. These studies have demonstrated exposure-response relationships for lung cancer, mesothelioma and asbestosis. For lung cancer, relatively consistent results have been observed, with risk two-fold or less in 13 of the 14 cohorts.

Cotton dust and across-shift change in FEV1 as predictors of annual change in FEV1.

In this report of a 5-yr longitudinal study of workers employed at six cotton textile mills, exposure and across-shift FEV1 change were evaluated as possible predictors of the annual change in FEV1 for yarn manufacturing workers. A total of 611 workers had three repeatable spirometric tests, over at least 3 yr, and at least one (average of three) across-shift test, while always working the same shift. The "same shift" criterion controlled for the effect of diurnal variation.