Blood lead levels among children of lead-exposed workers: A meta-analysis.

BACKGROUND: To further assess the utility of targeted blood lead screening for children from households with members having occupational lead exposures, we conducted a meta-analysis of all available reports of take-home lead exposures. Our objective was to estimate the blood lead levels among U.S. children (ages 1-5) from households with lead-exposed workers. METHODS: Reports considered for inclusion were cited in Medline, Toxline, Excerpta Medica, and Bio-Med plus all unpublished reports available at the National Institute for Occupational Safety and Health through 1994. The a priori criteria for inclusion of U.S. reports required their having data on: (1) venous blood lead levels for children, (2) children's ages, (3) data for at least five children, (4) workers' occupations, (5) workers' blood lead levels, and (6) data collection methods. RESULTS: Based on a meta-analysis of 10 reports from 1987 through 1994, the children (n=139) of lead-exposed workers (n=222) had a geometric mean blood lead level of 9.3 microg/dL compared to a U.S. population geometric mean of 3.6 microg/dL (P=0.0006). Also in this group, 52% of the children had blood lead levels (BLLs) >/= 10 microg/dL compared to 8.9% in the U.S. (P=.0010), and 21% of the children had BLLs >/= 20 microg/dL compared to 1.1% in the U.S. (P=. 0258). CONCLUSIONS: We estimate, based on 1981-83 survey data, that there are about 48,000 families with children under six living with household members occupationally exposed to lead. If the findings from this meta-analysis (admittedly limited by small numbers) are generalizable, about half of the young children in these families may have BLLs >/= 10 microg/dL. Data were too sparse to determine if children of workers with elevated blood leads were at greater risk than children whose parents were only known to be lead exposed. Our findings support the position that children of lead-exposed workers should be targeted for blood lead screening. Am. J. Ind. Med. 36:475-481, 1999. Published 1999 Wiley-Liss, Inc.

Modifiers of lung cancer risk in uranium miners from the Colorado Plateau.

Given the scientific consensus that exposure to radon decay products causes lung cancer, most recent studies have focused on the nature of the exposure-response relationship. Since residential radon exposure is now a primary public health issue, a better understanding of the effects of low levels of radon as well as factors modifying risk estimates has become very important. Several factors are shown to affect risk estimates in the latest update of the vital status follow-up (through 1990) and smoking history for the cohort of underground uranium miners in the Colorado Plateau. This analysis confirms earlier results indicating a strong dependence of relative risk estimates upon attained age. Quantitative estimates of relative risk as a function of cumulative exposure to radon decay products (WLM) are provided for three age strata. The non-linearity often reported in the Colorado Plateau data is shown to be at least partially due to an inverse exposure-rate effect, i.e., low exposure rates for long periods are more hazardous than equivalent cumulative exposure received at higher rates for shorter periods of time. However, this effect is shown to diminish at lower exposure rates and cumulative exposures. In addition, use of the new smoking data indicates that the radon/smoking interaction is submultiplicative and may depend upon attained age.

An update of mortality from all causes among white uranium miners from the Colorado Plateau Study Group.

To place previously recognized mortality risks into the context of the total mortality from all causes, an updated retrospective cohort mortality study was conducted on 3,238 white males from the US Public Health Service cohort of Colorado Plateau uranium miners. Vital status was followed from 1960 through 1990. Life-table analyses used combined New Mexico, Arizona, Utah, and Colorado mortality rates for external comparison and mortality risks within the lowest radon-exposure or duration-employed category for internal comparison. Significantly elevated SMRs were found for pneumoconioses (SMR = 24.1, 95% CI 16.0-33.7), lung cancer (SMR = 5.8, 95% CI 5.2-6.4), tuberculosis (SMR = 3.7, 95% CI 1.9-6.2), chronic obstructive respiratory diseases (SMR = 2.8, 95% CI 2.2-3.5), emphysema (SMR = 2.5, 95% CI 1.9-3.2), benign and unspecified tumors (SMR = 2.4, 95% CI 1.0-4.6), and diseases of the blood and blood-forming organs (SMR = 2.4, 95% CI 1.0-5.0). No significantly lowered SMRs were found for any disease. For lung cancer and pneumoconioses standardized rate ratios increased with increasing exposure to radon progeny or duration of employment. Most findings from this update are consistent with previous studies. Not observed were previously elevated SMRs for chronic nephritis and for acute alcoholism. New findings observed were elevated SMRs for benign and unspecified tumors and for diseases of the blood and blood-forming organs. The most important long-term mortality risks for the white uranium-miners continue to be lung cancer and pneumoconioses, for which SMRs remain significantly elevated after a mean period of 22.4 years since last uranium mining.

Pooled reanalysis of cancer mortality among five cohorts of workers in wood-related industries.

OBJECTIVES: To provide more information regarding the risk of cancer associated with wood dust, a pooled reanalysis of data from five cohort studies was performed. METHODS: The combined cohort consisted of 28,704 persons from five studies: British furniture workers, members of the union representing furniture workers in the United States, two cohorts of plywood workers, and one of wood model makers, among whom 7665 deaths occurred. Pooled analyses were carried out for all of the cohorts combined, the two furniture worker cohorts combined, and the two plywood workers cohorts combined. RESULTS: Significant excesses of nasal [observed 11, standardized mortality ratio (SMR) 3.1, 95% confidence interval (95% CI) 1.6-5.6] and nasopharyngeal (observed 9, SMR 2.4, 95% CI 1.1-4.5) cancer were observed. That for nasal cancer appeared to be associated with exposure to wood dust but was based solely on cases from the British furniture worker cohort, while that of nasopharyngeal cancer was observed for furniture and plywood workers and was associated with both high and low probability of wood dust exposure. Some support for an excess risk of multiple myeloma was also observed but was less clearly associated with wood dust exposure. No excesses of lung, larynx, stomach, or colon cancer were found to be associated with any surrogate indicators of wood dust exposure. CONCLUSIONS: Workers exposed to wood dust may have an excess risk of nasopharyngeal cancer and multiple myeloma in addition to sinonasal cancer. The limitations of this study would tend to obscure relationships, rather than create false positive findings.

Mortality among Navajo uranium miners.

OBJECTIVES: To update mortality risks for Navajo uranium miners, a retrospective cohort mortality study was conducted of 757 Navajos from the cohort of Colorado Plateau uranium miners. METHODS: Vital status was followed from 1960 to 1990. Standardized mortality ratios were estimated, with combined New Mexico and Arizona non-White mortality rates used for comparison. Cox regression models were used to evaluate exposure-response relationships. RESULTS: Elevated standardized mortality ratios were found for lung cancer (3.3), tuberculosis (2.6), and pneumoconioses and other respiratory diseases (2.6). Lowered ratios were found for heart disease (0.6), circulatory disease (0.4), and liver cirrhosis (0.5). The estimated relative risk for a 5-year duration of exposure vs none was 3.7 for lung cancer, 2.1 for pneumoconioses and other respiratory diseases, and 2.0 for tuberculosis. The relative risk for lung cancer was 6.9 for the midrange of cumulative exposure to radon progeny compared with the least exposed. CONCLUSIONS: Findings were consistent with those from previous studies. Twenty-three years after their last exposure to radon progeny, these light-smoking Navajo miners continue to face excess mortality risks from lung cancer and pneumoconioses and other respiratory diseases.

Mortality patterns among construction workers in the United States.

Thirteen authors from the National Institute for Occupational Safety and Health contribute to this summary of recent and ongoing national occupational mortality surveillance studies of construction workers, including studies conducted under NIOSH's Fatality Assessment and Control Evaluation project, Sentinel Health Events project, National Occupational Mortality Surveillance System, and other projects.

Colon and stomach cancer mortality among automotive wood model makers.

Automotive wood model makers have been reported to be at excess risk for colon and other cancers in recent epidemiologic studies. To further explore these risks, we conducted a retrospective cohort mortality study, with follow-up from 1940 through 1984, of 2294 white male wood model makers employed at any time until 1980 by three US auto makers. Using US mortality rates for comparison, we found elevated standardized mortality ratios of 1.2 (95% CI, 0.8-1.9) for colon cancer and 1.6 (95% CI, 0.9-2.6) for stomach cancer. We also conducted nested case-control studies for 20 colon and 17 stomach cancer cases and 543 age-matched controls. We found no trend of increased risk for colon or stomach cancer mortality with increased exposure to wood dust or to duration employed in wood model making.

Lung cancer mortality among nonsmoking uranium miners exposed to radon daughters.

Radon daughters, both in the workplace and in the household, are a continuing cause for concern because of the well-documented association between exposure to radon daughters and lung cancer. To estimate the risk of lung cancer mortality among nonsmokers exposed to varying levels of radon daughters, 516 white men who never smoked cigarettes, pipes, or cigars were selected from the US Public Health Service cohort of Colorado Plateau uranium miners and followed up from 1950 through 1984. Age-specific mortality rates for nonsmokers from a study of US veterans were used for comparison. Fourteen deaths from lung cancer were observed among the nonsmoking miners, while 1.1 deaths were expected, yielding a standardized mortality ratio of 12.7 with 95% confidence limits of 8.0 and 20.1. These results confirm that exposure to radon daughters in the absence of cigarette smoking is a potent carcinogen that should be strictly controlled.