Cumulative Exposure Score Research Articles

Exposure to tetrachloroethylene via contaminated drinking water pipes in Massachusetts: a predictive model.

A computer model was developed to estimate exposure to tetrachloroethylene leaching from drinking-water pipes in Massachusetts between 1968 and 1979. The model was to be used for an epidemiologic study of cancer in five communities in Massachusetts. This model assigned a relative cumulative exposure score to each individual participant in the study, based on the geometry, size, age, and water flow through the water pipe that supplied a particular household and on the individual's duration of residence in that household. The results of modeling showed a wide range of exposure levels among the study participants. The epidemiologic study is described in the accompanying paper by Aschengrau et al.

Inter-rater agreement in the assessment of solvent exposure at a car assembly plant.

This study investigated the feasibility and the reproducibility of a retrospective assessment of solvent exposure in the painting operations of a car assembly plant. Five industrial hygienists (the raters) reviewed summary documents on plant operations and solvent exposure levels, developed from plant records and interviews. The raters independently reviewed 695 department-job-year combinations compiled from 29 work histories and used semi-quantitative scores to rate solvent exposure. Inter-rater agreement was evaluated by computing the percent concordance index and the intraclass correlation coefficient (rI). There was discordance among raters, a large proportion of which pertained to low exposure levels (1-5 ppm). The computation of the rI is sensitive to the distribution of exposure levels. A low rI can be observed for a rare exposure even if the percent concordance is high. Inter-rater agreement was good for cumulative exposure scores computed for frequent exposures: coatings (rI = 0.67), aromatic hydrocarbons (rI = 0.66), and petroleum distillates (rI = 0.62).

Inter-rater Agreement in the Assessment of Solvent Exposure at a Car Assembly Plant

This study investigated the feasibility and the reproducibility of a retrospective assessment of solvent exposure in the painting operations of a car assembly plant. Five industrial hygienists (the raters) reviewed summary documents on plant operations and solvent exposure levels, developed from plant records and interviews. The raters independently reviewed 695 department-job-year combinations compiled from 29 work histories and used semi-quantitative scores to rate solvent exposure. Inter-rater agreement was evaluated by computing the percent concordance, index and the intra-class correlation coefficient (r1). There was discordance among raters, a large proportion of which pertained to low exposure levels (1–5 ppm). The computation of the r1, is sensitive to the distribution of exposure levels. A low r1 can be observed for a rare exposure even if the percent concordance is high. Inter-rater agreement was good for cumulative exposure scores computed for frequent exposures: coatings (r1=0.67), aromatic hydrocarbons (r1=0.66), and petroleum distillates (r1=0.62).

Lung cancer and hydrogen chloride exposure: Results from a nested case-control study of chemical workers : Bond GG, Flores GH, Stafford BA, Olsen GW. Department of Epidemiology, Health and Environmental Sciences, Dow Chemical Company, 1803 Building, Midland, MI 48674. J Occup Med 1991;33:958–61

There are few epidemiologic data available to address the question of potential carcinogenic effects of hydrogen chloride (HCl) exposure on humans. An opportunity arose to augment a nominal HCl exposure classification that had been done earlier for a nested case-control study of lung cancer among a cohort of chemical manufacturing employees. Working from first-hand knowledge of the relevant chemical processes and limited HCl monitoring data, a certified industrial hygienist estimated average exposures for each of the job assignments of 308 lung cancer cases and 616 comparison workers. The risk of lung cancer was then analyzed in relation to several measures of HCl exposure, including duration, a cumulative exposure score, highest average exposure, and latency. None showed evidence of an association between HCl exposure and lung cancer. This is consistent with the limited rodent bioassay data, which also failed to find a tumorigenic response from HCl. Thus, even at high level occupational exposures (up to 3000 micrograms/m3 for several years) there is no evidence that HCl is a human carcinogen.

Olfactory function in chemical workers exposed to acrylate and methacrylate vapors.

An investigation of the olfactory function of 731 workers at a chemical facility which manufacturers acrylates and methacrylates was undertaken using a standardized quantitative test. In a cross-sectional analysis of the data, no associations of chemical exposure with olfactory test scores were observed. A nested case-control study designed to evaluate the cumulative effects of exposure on olfactory function, however, revealed elevated crude exposure odds ratios (95% confidence interval) of 2.0 (1.1, 3.8) for all workers and 6.0 (1.7, 21.5) for workers who never smoked cigarettes. Logistic regression analysis, adjusting for multiple confounders, revealed exposure odds ratios of 2.8 (1.1, 7.0) and 13.5 (2.1, 87.6) in these same groups, respectively, and a dose-response relationship between olfactory dysfunction and cumulative exposure scores--semi-quantitative indices of lifetime exposure to the acrylates. The data also revealed decreasing exposure odds ratios with increasing duration since last exposure to these chemicals, suggesting that the effects may be reversible.

An Industry-Wide Study of Respiratory Cancer in Chemical Workers Exposed to Chloromethyl Ethers<xref ref-type="fn" rid="FN2">2</xref>

An industry-wide retrospective cohort mortality study was conducted on 6,152 chemical workers (2,460 exposed and 3,692 nonexposed) engaged in chloromethyl ether manufacture at 7 major U.S. companies between 1948 and 1980. A previous study at 6 companies from 1948 through 1972 reported excess respiratory cancer (RC) mortality and significant exposure-response relationships in exposed workers at 1 company (company 2). The present study, which extended follow-up of an additional 7 years for companies 1-6 and included company 7 for follow-up from 1953 through 1980, found excess RC mortality in exposed workers at company 2 [observed (Obs) = 32, standardized mortality ratio (SMR) = 430] and company 7 (Obs = 9, SMR = 603). External comparisons of RC mortality at both companies showed significant exposure-response relationships with respect to cumulative time-weighted exposure. At company 2, where the greatest number of RC deaths occurred, external comparisons showed that RC risk remained constant in relation to age at first exposure and decreased with increasing time since last exposure. With the use of Mantel-Haenszel and relative risk (RR) regression methods, internal comparisons at company 2 demonstrated significant findings of increasing RR with cumulative duration of exposure and cumulative time-weighted exposure and with decreasing time since last exposure. No association was found between RR and age at first exposure. An interesting finding was a significant negative interaction between cumulative time-weighted exposure and age at risk. The best-fitting logistic regression model for the exposed group predicted RR at 2.79 (95% confidence interval = 1.66-4.69) for workers with the mean cumulative exposure score of the 32 RC deaths (lagged by 6 yr) compared with those with negligible exposure (assuming mean age at risk of the RC deaths, 51 years old, and time since last exposure held constant). Qualitative assessment of the results suggests that chloromethyl ether exposure affects both an early as well as a late stage of a putative multistage respiratory malignant process.