Continuing exposure to hexavalent chromium,a known lung carcinogen: an analysis of OSHA compliance inspections, 1990-2000

BACKGROUND: Hexavalent chromium is widely recognized to be a lung carcinogen. However, the U.S. Occupational Safety and Health Administration (OSHA) has failed to reduce the permissible exposure limit (PEL), despite having acknowledged in 1994 that the current limit is too high. In 1993, Public Citizen and the Paper, Allied-Industrial, Chemical and Energy Workers International Union (PACE) petitioned to lower the PEL from the current 100 microg/m(3) to 0.5 microg/m(3) as an 8-hr time-weighted average (TWA). METHODS: To assess industry compliance with the current PEL, and to determine the feasibility of achieving the proposed lower limit of 0.5 microg/m(3), we conducted a secondary data analysis of OSHA's Integrated Management Information System (IMIS) database. This database contains 813 measurements of hexavalent chromium exposure from inspections performed during the years 1990-2000. RESULTS: There was a statistically significant decline in the annual number of measurements over the study period from 127 in 1990 to 67 in 2000 (F = 0.0009; linear regression). The median TWA measurement was 10 microg/m(3) (range: 0.01-13,960 microg/m(3)) and the median ceiling measurement was 40.5 microg/m(3) (range: 0.25-25,000 microg/m(3)). Neither median TWA nor median ceiling exposures (if hexavalent chromium was detected) declined significantly during the study period (F = 0.065 and 0.57, respectively). Overall, 13.7% of TWA measurements were at or below the Public Citizen/PACE proposed standard; 65.0% were between the Public Citizen/PACE proposal and the current OSHA PEL; and 21.3% exceeded the OSHA PEL. Compared to OSHA measurements, state measurements were less likely to detect hexavalent chromium (40.2% vs. 52.1%; P = 0.0007; chi-square) and less likely to issue any citation (9.3% vs. 19.1%; P = 0.0003), including citations for overexposure if the exposure exceeded the PEL (54.8% vs. 78.8%; P = 0.012). CONCLUSIONS: U.S. workers continue to be exposed to dangerously high hexavalent chromium levels, but low exposure levels were found in some industries. Further investigations should examine whether state plans provide weaker enforcement than federal OSHA.     

Risk of lung cancer among former chromium smelter workers

Hexavalent chromium is a known carcinogen. Previous epidemiologic studies in the 1950s of United States workers from seven facilities producing chromium compounds from chromite ore have reported a markedly increased risk for dying from lung cancer. As part of a high risk notification project of workers from four of these facilities, a mortality study was performed. The cohort was assembled in 1990–1991 from the Social Security records of four former chromate producing facilities in northern New Jersey. The study subjects were known to have worked at these facilities some time between 1937 and 1971. Proportionate mortality and proportionate cancer mortality ratios (PCMR) were calculated. The overall risk for lung cancer was a PCMR of 1.51 (confidence limits [CL] 1.29–1.74) for white men and 1.34 (CL 1.00–1.75) for black men. These risks increased with increasing duration of employment and latency since time of first employment. The PCMR for greater than 20 years duration of work and more than 20 years since first exposure was 1.94 (CL 1.15–3.06) for white men and 3.08 (CL 1.13–6.71) for black men. The risk for lung cancer for white men remains elevated more than 20 years after exposure has ceased (PCMR, 1.29; CL 1.03–1.60). The PCMR for nasal cavity/sinus cancer was also found to be a significantly increased, 5.18 (CL 2.37–11.30). A cluster of bladder cancer was seen among black workers from one facility, (PCMR, 3.30; CL 1.42–6.51). Despite the cessation of exposure, former chromium workers remain at significantly increased risk of lung cancer. Although there have been case reports of nasal cavity/sinus cancer in association with chromium exposure, this is the first epidemiologic study to report a significant increase in these cancers. Limitations in this study include lack of exposure data and lack of information on smoking habits. The lack of increase in other smoking-related diseases besides lung cancer indicates that the increase in lung cancer cannot be attributed to cigarette smoking. The ongoing elevated risk of lung cancer after cessation of exposure emphasizes the need for developing early detection tests for lung cancer. © 1996 Wiley-Liss, Inc.     

Cancer mortality among a cohort of chromium pigment workers

A study of mortality among 1,879 male workers employed in a New Jersey chromium pigment factory was carried out, with follow-up from 1940 to 1982. Vital status of 1,737 (92%) of the eligible cohort members was determined. For all malignant neoplasms, 101 deaths were observed while 108.8 were expected, SMR = 93 (standardized mortality ratio; n.s.). For the entire study group, no significant excess was observed for respiratory cancer or cancer at other sites. However, the total number of years of employment in the factory and the total number of years of exposure to chromate dusts were both statistically significantly (p less than .05, for trend) associated with an increased risk for lung cancer. The excess risk for lung cancer associated with duration of exposure to chromate dusts was, however, only clearly apparent for subjects followed for 30 years or more after initial employment. For this group, the SMRs were 81, 139, 201, and 321 for the subjects with 0 years, less than 1 year, 1-9 years, and 10+ years of exposure to chromate dusts (p less than .01, for trend), respectively. The risk for digestive cancer was only weakly associated with exposure to chromate dusts.     

Case-control study of exposure to carbon black in the occupational setting and risk of lung cancer

Although it has been hypothesized that carbon black exposure may carry an excess risk of lung cancer, evidence to date is insufficient to assess the hypothesis properly. The relationship between workplace exposure to carbon black and lung cancer risk was examined in a population-based case-control study carried out in Montreal, Canada. Detailed job histories were elicited from 857 incident cases with histologically confirmed lung cancer as well as from 1,360 cancer controls and 533 population controls. Job histories were evaluated by a team of hygienists and chemists for evidence of exposure to a host of occupational substances, including carbon black. Logistic regression analyses adjusting for smoking and other nonoccupational and occupational potential confounders suggested no significant increase in risk with relatively low exposure to carbon black. Some increase in risk for all lung cancers was apparent with relatively high exposure using cancer controls (OR = 2.17; 95% CI = 0.95–4.91) and population controls (OR = 1.52; 95% CI = 0.58–3.97). Individuals with relatively high exposure had a significantly greater risk of oat-cell carcinoma using either control series (OR = 5.05; 95% CI = 1.72–14.87 using cancer controls and OR = 4.82; 95% CI = 1.36–17.02 using population controls). These results provide some evidence for an association between exposure to carbon black and lung cancer. © 1996 Wiley-Liss, Inc.     

一株除铬(Ⅵ)菌株的筛选和鉴定

目的 分离、驯化和鉴定高效除铬(Ⅵ)菌株。 方法 从某电镀厂聚集区域的环境中采集样品,接种逐步升高铬(Ⅵ)浓度的培养基分离筛选出耐铬(Ⅵ)菌株,通过比较各菌株的除铬(Ⅵ)能力筛选出高效除铬(Ⅵ)菌株,并采用革兰氏染色、生理生化实验、16S rDNA等技术进行菌种鉴定。 结果 菌株CQMU-1的除铬效果最好;CQMU-1为革兰氏阴性球菌或短杆菌;能在500mg/L的含铬(Ⅵ)LB肉汤中生长,但生长受抑制;其最适生长pH为7.0～8.0,温度为20～35℃,好氧,化能异养,能利用大多数碳水化合物;经16S rDNA鉴定CQMU-1为产碱菌属。 结论 筛选出1株高效除铬(Ⅵ)菌株,可用于去除环境中铬(Ⅵ)污染。     

Vascular effects of occupational exposure to low-dose ionizing radiation

Damage to the microcirculation caused by high-dose ionizing radiation is well known but data concerning low-dose exposure are scant and contrasting. We employed capillary microscopy to study dermal microcirculation damage resulting from occupational exposure to ionizing radiation doses lower than 5 rem/year (maximum permissible dose in Italy). We studied 145 physicians (60.7% radiologists, 33.8% orthopedic specialists, 5.5% cardiologists) occupationally exposed to ionizing radiation and a control group of 106 subjects in comparable but different occupations not exposed to ionizing radiation or to other skin hazards. All subjects were administered a clinical protocol and underwent capillary microscopy of the fingernail-fold. Capillary microscopy alterations were classified as absent, mild, moderate, marked and severe. Our data confirm that occupational exposure to low-dose ionizing radiation can lead to morphological and functional alterations of the dermal microcirculation, which can be identified early by capillary microscopy. © 1996 Wiley-Liss, Inc.     

蜡样芽孢杆菌还原六价铬效果分析

目的 探索蜡样芽孢杆菌Cr4-1对六价铬[Cr（VI）]的还原特性。方法 采用正交试验研究温度、pH、初始Cr（VI）浓度、摇床转速对细菌生长和Cr（VI）还原的影响;使用9种常见碳源进行细菌生长和Cr（VI）还原试验,筛选最佳碳源和电子供体;采用透射电子显微镜观察不同浓度Cr（VI）还原细菌,细菌前后形态的变化。结果 影响该细菌生长的主要因素是摇床转速和pH值,影响Cr（VI）还原细菌的主要因素是初始Cr（VI）浓度和温度。细菌生长和Cr（VI）还原的较优条件是温度35℃、pH=9、初始Cr（VI）浓度为30 mg/L、转速150 r/min。乳酸钠是细菌生长和Cr（VI）还原的较好碳源,其次是丙酮酸钠。透射电镜观察发现,初始Cr（VI）浓度为30 mg/L和60 mg/L时,还原过程中Cr（VI）对细菌具有毒性作用,浓度越高,细菌损伤越严重。结论 蜡样芽孢杆菌Cr4-1对Cr（VI）的还原效果明显,具有较好的应用前景。     

Lung cancer risk in past asbestos workers a few decades after exposure cessation and prospects for screening

To ascertain whether the current risk of lung cancer in former asbestos workers was higher than in the general population, 1,557 past asbestos workers were recruited during statutory health examinations (from 2000 onward) and followed up for mortality. Standardized mortality ratios (SMRs) were calculated. Poisson regression was used to adjust the rate ratios (RRs) for confounders. SMR was about 1.00 in workers with or without pleural plaques and 4.62 (95% confidence interval: 0.61–18.1) in those with asbestosis. Adjusted RRs for lung cancer were 4.70 (0.99–22.5) for asbestosis, 4.35 (0.97–19.5) for former smokers, 6.82 (1.38–34.4) for current smokers. Currently, lung cancer mortality in past asbestos workers is similar to the general population, probably because workers more exposed /more susceptible could have died from lung cancer before the beginning of follow-up.     

Pleural malignant mesothelioma in Tuscany, Italy (1970-1988): II. Identification of occupational exposure to asbestos.

Following the finding of an unexpected cluster of mesotheliomas in textile workers, a surveillance system of malignant mesotheliomas was implemented in the region of Tuscany, Italy. This article reports on the investigation of 124 cases of mesothelioma diagnosed and reviewed by the Institutes of Morbid Anatomy and Histopathology at the Universities of Florence, Pisa, and Siena between 1970 and 1988. A complete occupational and asbestos exposure history was assessed through a semi-structured questionnaire directly administered to resident cases of Tuscany or, if deceased, to their closest living relatives, for a total of 100 interviews. The hypothesis of past occupational asbestos exposure was verified and documented. Seventy-two cases have been classified as occupationally exposed to asbestos; four were classified in the category of "possible domestic" exposure to asbestos. For two others, the role of other risk factors was stressed, and for 22 cases, either no asbestos exposure was found or the available data were not adequate to define it. The present study allowed identification of some unknown or scarcely known occupational asbestos exposures in the study area.     

Mortality surveillance and occupational hazards: the Solutia mortality experience 1980-94

OBJECTIVES—Several investigators argue that company wide mortalities for recent workers allow early identification of potential workplace hazards. Mortalities for recent workers were compared with published studies of workers with specific exposures in the same company to find whether mortality surveillance results could be used to identify previously unknown health effects from workplace hazards.
METHODS—Relative risks for causes of death in published substance specific studies at the plants were compared with the relative risks in the mortality surveillance of workers 20 or more years after first being employed.
RESULTS—As reported by other companies, low mortalities were found among workers in the mortality surveillance. The mortality surveillance reports often found no increased risk of disease at plants in which substance specific studies had found no effects. However, disease specific relative risks were not found by the mortality surveillance predictions of relative risks in the substance specific studies with increased risk.
CONCLUSION—Mortality surveillance is of limited use for identifying health effects from past workplace exposures to specific materials. The healthy worker and survivor effects, the failure to identify subsets of workers exposed to potentially toxic substances, the typically long induction period between exposure and disease, and the inability of recent mortality levels to reflect historical conditions all may make it difficult to use mortality surveillance to identify workplace hazards. Combining mortality surveillance with studies of workers with potentially toxic exposures helps identify occupational hazards.


Keywords: mortality surveillance; occupational cancer; bladder cancer; leukaemia     

A retrospective assessment of occupational exposure to elemental carbon in the U.S. trucking industry

Background: Despite considerable epidemiologic evidence about the health effects of chronic exposure to vehicle exhaust, efforts at defining the extent of risk have been limited by the lack of historical exposure measurements suitable for use in epidemiologic studies and for risk assessment.Objectives: We sought to reconstruct exposure to elemental carbon (EC), a marker of diesel and other vehicle exhaust exposure, in a large national cohort of U.S. trucking industry workers.Methods: We identified the predictors of measured exposures based on a statistical model and used this information to extrapolate exposures across the cohort nationally. These estimates were adjusted for changes in work-related conditions over time based on a previous exposure assessment of this industry, and for changes in background levels based on a trend analysis of historical air pollution data, to derive monthly estimates of EC exposure for each job and trucking terminal combination between 1971 and 2000.Results: Occupational exposure to EC declined substantially over time, and we found significant variability in estimated exposures both within and across job groups, trucking terminals, and regions of the United States. Average estimated EC exposures during a typical work shift ranged from < 1 μg/m³ in the lowest exposed category in the 1990s to > 40 μg/m³ for workers in the highest exposed jobs in the 1970s.Conclusions: Our results provide a framework for understanding changes over time in exposure to EC in the U.S. trucking industry. Our assessment should minimize exposure misclassification by capturing variation among terminals and across U.S. regions, and changes over time.     

A case-control study of occupational exposure to trichloroethylene and non-Hodgkin lymphoma

Background

Previous epidemiologic findings suggest an association between exposure to trichloroethylene (TCE), a chlorinated solvent primarily used for vapor degreasing of metal parts, and non-Hodgkin lymphoma (NHL).

Objectives

We investigated the association between occupational TCE exposure and NHL within a population-based case–control study using detailed exposure assessment methods.

Methods

Cases (n = 1,189; 76% participation rate) and controls (n = 982; 52% participation rate) provided information on their occupational histories and, for selected occupations, on possible workplace exposure to TCE using job-specific interview modules. An industrial hygienist assessed potential TCE exposure based on this information and a review of the TCE industrial hygiene literature. We computed odds ratios (ORs) and 95% confidence intervals (CIs) relating NHL and different metrics of estimated TCE exposure, categorized using tertiles among exposed controls, with unexposed subjects as the reference group.

Results

We observed associations with NHL for the highest tertiles of estimated average weekly exposure (23 exposed cases; OR = 2.5; 95% CI, 1.1–6.1) and cumulative exposure (24 exposed cases; OR = 2.3; 95% CI, 1.0–5.0) to TCE. Tests for trend with these metrics surpassed or approached statistical significance (p-value for trend = 0.02 and 0.08, respectively); however, we did not observe dose–response relationships across the exposure levels. Overall, neither duration nor intensity of exposure was associated with NHL, although we observed an association with the lowest tertile of exposure duration (OR = 2.1; 95% CI, 1.0–4.7).

Conclusions

Our findings offer additional support for an association between high levels of exposure to TCE and increased risk of NHL. However, we cannot rule out the possibility of confounding from other chlorinated solvents used for vapor degreasing and note that our exposure assessment methods have not been validated.     

Death certificate-based occupational mortality surveillance in the United States

Surveillance of cause-specific mortality patterns by occupation and industry through the use of death certificate records is a simple and relatively inexpensive approach to the generation of leads as to potential occupational disease problems. Researchers from the National Institute for Occupational Safety and Health (NIOSH) have been working with the National Center for Health Statistics, other federal agencies, and state health departments on a number of programs to foster the development of standardized, routine coding of occupation and industry entries on death certificates by state health departments. Thirty-one states and the District of Columbia are now doing such coding. These data are being analyzed currently by investigators at NIOSH and at individual state health departments for the purpose of hypothesis generation on occupation-disease relationships. The proportionate mortality ratio method is the predominant method being used, as appropriate denominator data are not generally available. This type of surveillance is particularly useful for the study of occupation and industry groups for which it is difficult to assemble cohorts, such as groups that are predominantly non-union and in small workplaces. Limitations of this surveillance include its inappropriateness for monitoring those occupational diseases which are not often fatal, and the limited scope and accuracy of death certificate information.     

An update of respiratory cancer and occupational exposure to arsenicals

Mortality was updated through 1982 for 611 arsenic-exposed employees originally studied through 1973. In the earlier report, total mortality was observed to have been below the comparable U.S. population; however, mortality was significantly elevated for respiratory cancer. The focus of the update was on respiratory cancer and of special interest was whether the risk of respiratory cancer remained in excess for individuals alive as of the end of the last study. In the update, 9 additional respiratory cancers were observed subsequent to 1973, the end of the follow-up in the original study, versus 7.8 expected. The risk ratio for the time-interval 1974-1982 (standardized mortality ratio SMR = 116) was diminished compared to that reported in the original study (SMR = 330). When the entire study period was analyzed, the risk of respiratory cancer did not appear to decline with interval since exposure cessation. Analyses by duration of arsenic exposure and interval since first exposure did not reveal any obvious dose-response relationships.     

Social disparities in the burden of occupational exposures: results of a cross-sectional study

BACKGROUND: Most occupational studies evaluate a single exposure in relation to a particular disease. However, workers typically experience multiple exposures simultaneously. There is also increasing evidence of disparities in health by sociodemographic characteristics, mostly related to social position such as gender, race/ethnicity, immigration status, income, and education. Little information exists on the worker experience of multiple occupational exposures as they vary among social groups. The objectives of this article were to: assess the burden of exposures reported within 1 year by a socially diverse population working in a range of industries; and evaluate whether sociodemographic characteristics affected the patterns of these exposures. METHODS: Study participants were from 14 unionized worksites in meat processing, electrical lighting manufacturing, retail grocery stores, and school bus driving. A cross-sectional study design used a self-administered, computer-assisted questionnaire (English and Spanish) to assess sociodemographic characteristics and nine workplace exposures, within the past year. An interviewer-administered job history also was collected. RESULTS: Twelve hundred eighty-two workers (72%) completed the survey: 36% women, 23% Latino, 39% black, 24% white, and 48% born outside the US. The prevalence of high exposures ranged from 21% (chemicals) to 39% (neck strain). Forty-six percent reported three or more high exposures. Exposure reporting varied among sociodemographic groups. Some of the disparities were explained by the jobs held by different groups, but after statistically controlling for job, many disparities remained. CONCLUSIONS: Sociodemographic characteristics should be considered when conducting exposure assessments using questionnaires. More research is needed to understand how social characteristics may influence exposures.