Quantification of historical exposures in occupational cohort studies

Relatively few investigators have estimated quantitative exposure levels in epidemiologic studies, and, for those that have, few have discussed the strengths and weakness of their estimation method with respect to other methods. This paper reviews the steps for developing quantitative exposure estimates that have been used in published studies. First, the qualitative considerations to be evaluated in the selection of the agent to be estimated (i.e., the disease mechanism, the effects of exposure mixtures and interactions, the physical state of the agent, and the routes of exposures) are discussed. Considerations for developing exposure groups are then presented, including work history and exposure information characteristics, the homogeneity of exposures within exposure groups, the exposure estimation method, and the disease risk analyses to be performed. The various exposure estimation approaches are reviewed for their strengths and weaknesses, including the calculation of the mean exposures from existing exposure measurements, statistical models, measurement data from surrogate exposures, and professional judgment. Recommendations for future studies are provided.     

Estimating correlations from epidemiological data in the presence of measurement error

Analysis of a major multi-site epidemiologic study of heart disease has required estimation of the pairwise correlation of several measurements across subpopulations. Because the measurements from each subpopulation were subject to sampling variability, the Pearson product moment estimator of these correlations produces biased estimates. This paper proposes a model that takes into account within and between sub-population variation, provides algorithms for obtaining maximum likelihood estimates of these correlations and discusses several approaches for obtaining interval estimates.     

Occupational and environmental exposures and nonspecific lung disease--a review of selected studies

Selected studies show that nonspecific lung diseases are a major occupational and environmental health hazard. Exposure to mineral dusts (such as cement and brown coal) and organic dusts (cotton, hemp and flour) as well as manganese and gaseous irritants causes significant upper respiratory tract injury. Possible additive effects of mixed exposures, combined exposure to dusts and gaseous irritants of the upper respiratory tract, individual susceptibility, and mechanisms of nonspecific respiratory effects of exposures are considered. Interpretation of the results is difficult due to uncontrolled confounding. Measures for preventing lung impairments include exposure reduction and preemployment examination of workers.     

Risk of stillbirth from occupational and residential exposures

OBJECTIVES: To analyse the risk of stillbirth from 12 residential and occupational maternal exposures during pregnancy. METHODS: Stillbirths and neonatal deaths in 1984 within 24 hours of birth from 10 California counties were identified from death certificates. Controls were randomly selected from live births born in 1984 and frequency matched to cases by maternal age and county. Data sources included vital statistics and a self-administered postal questionnaire. Logistic regression and proportional hazards modelling were performed; the proportional hazards considered the truncated opportunity for exposure among cases. Special focus was given to two cause of deaths groups: congenital anomalies (12% of deaths) and complications of the placenta, cord, and membranes (37% of deaths). RESULTS: Occupational exposure to pesticides during the first two months of gestation was positively associated with stillbirths due to congenital anomalies (odds ratio (OR) 2.4, 95% confidence interval (95% CI) 1.0 to 5.9), and during the first and second trimesters with stillbirths due to all causes of death (risk ratios (RR) 1.3-1.4, 95% CI 1.0 to 1.7) and stillbirths due to complications of the placenta, cord, and membranes (RR 1.6-1.7, 95% CI 1.1 to 2.3). Occupational exposure to video display terminals in the third trimester was found to have a modest inverse association with stillbirths (RR 0.7, 95% CI 0.6, 0.9). Home pesticide exposure was positively associated with stillbirths due to congenital anomalies (OR 1.7, 95% CI 1.0 to 2.9). CONCLUSIONS: Occupational exposure to pesticides, especially during early pregnancy, had a clear positive association with stillbirths regardless of cause of death. Methodologically, this study of stillbirths is unique in its analysis of specific causes of death and use of time specific exposure windows.     

Case-control study of occupational exposures and male breast cancer

OBJECTIVE: To investigate whether risk of male breast cancer is associated with workplace exposures. METHODS: A case-control study of 178 cases of male breast cancer and 1041 controls was carried out with data from the United States national mortality follow-back survey, which collected questionnaire information from proxy respondents of a 1% sample of all 1986 United States deaths among subjects aged 25-74 years. Occupational exposure to electromagnetic fields, high temperatures, polycyclic aromatic hydrocarbons (PAHs), herbicides, other pesticides, and organic solvents was assessed by applying job-exposure matrices, based on the 1980 United States census occupation and industry codes, to the longest job held by study subjects as reported by the informants. A socioeconomic status index was created by combining information on annual family income, education, assets, and occupation to assess the association of socioeconomic status with male breast cancer. Relative risks were derived from logistic regression modelling, which included age, socioeconomic status, marital status, and body mass index, as well as occupational exposures. RESULTS: Risk for male breast cancer increased significantly with increasing socioeconomic status index (test for trend: p < 0.01), but the risks associated with individual socioeconomic status variables were smaller and the trends were not significant. A significant increase in risk of male breast cancer was associated with employment in blast furnaces, steel works, and rolling mills (odds ratio (OR) 3.4; 95% confidence interval (95% CI) 1.1 to 10.1, based on six cases), and motor vehicle manufacturing (OR 3.1; 95% CI 1.2 to 8.2, based on seven cases). However, exposures to electromagnetic fields, high temperature, PAHs, herbicides, other pesticides, and organic solvents were not associated with risk of male breast cancer. CONCLUSIONS: The role of workplace exposures in increasing risk of breast cancer among men employed in motor vehicle manufacturing and in blast furnaces, steel works, and rolling mills deserves further investigation. The finding on socioeconomic status suggests that, as well as reproductive factors, other lifestyle factors such as diet that may be related to high socioeconomic status in men should be investigated further.     

The potential impact on women from environmental exposures

BACKGROUND: Vascular complications following laparoscopic techniques may often be attributed to the incomplete control of bleeding sites at laparoscopy. When confronted with post-laparoscopy symptoms of hemodynamic insufficiency, the surgeon may infer the existence of hemorrhagic complications neglected at the laparoscopic session. METHODS: The author reviewed two otherwise normal cases of laparoscopic procedures that were complicated by bleeding disorders of unknown origin. RESULTS: Diagnosis and treatment of the hematologic complications revealed causes other than operator-inflicted injury. CONCLUSIONS: While laparoscopists should remain vigilant concerning the very real threat of overlooked vascular injury following laparoscopy, some patients may exhibit hemorrhagic symptoms unrelated to the laparoscopic procedure.     

Inherited factors and environmental exposures in cancer risk

Carcinogenesis is a multistage process that results from the interaction of carcinogenic exposures, cellular macromolecules (eg, DNA), and endogenous mutational mechanisms. Involved in these processes are metabolic activation and detoxification of chemical carcinogens, genetic sequences of protooncogenes and tumor suppressor genes, and DNA repair, among others. Each of these vary widely among individuals and can be associated with increased cancer risk. Cytochrome P4501A1, P4502E1 and N-acetyl transferase 2 are examples of enzymes involved in the metabolic activation of potential environmental carcinogens such as polycyclic aromatic hydrocarbons, benzene, and aromatic amines, respectively. Germ-line mutations in these genes are common and associated with abnormal enzymatic function that are mechanistically related to quantitative changes in binding of carcinogens to DNA. Allelic frequencies for these mutations vary among different racial and ethnic populations and may explain, in part, differences in cancer rates. Risk assessments attempt to predict cancer rates in humans using mathematical models that are often based upon limited experimental data. They do not generally incorporate the numerous stages of carcinogenesis or interindividual variation. Thus, sensitive and resistant populations are not sufficiently considered. This limits the accuracy of currently applied risk assessment models.     

Effects of terminal ranking error on meaningful occupational choice.

Investigated the existence of terminal error (the tendency to overevaluate the first and the last positions in ranking a set of entities) in the ranking of occupations for trustworthiness by 3 groups of 120 undergraduate Ss each. It was found that terminal error occurred, but that it disappeared as intrinsic differences among the occupations to be ranked became more pronounced. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Renal effects of environmental and occupational lead exposure

Environmental and industrial lead exposures continue to pose major public health problems in children and in adults. Acute exposure to high concentrations of lead can result in proximal tubular damage with characteristic histologic features and manifested by glycosuria and aminoaciduria. Chronic occupational exposure to lead, or consumption of illicit alcohol adulterated with lead, has also been linked to a high incidence of renal dysfunction, which is characterized by glomerular and tubulointerstitial changes resulting in chronic renal failure, hypertension, hyperuricemia, and gout. A high incidence of nephropathy was reported during the early part of this century from Queensland, Australia, in persons with a history of childhood lead poisoning. No such sequela has been found in studies of three cohorts of lead-poisoned children from the United States. Studies in individuals with low-level lead exposure have shown a correlation between blood lead levels and serum creatinine or creatinine clearance. Chronic low-level exposure to lead is also associated with increased urinary excretion of low molecular weight proteins and lysosomal enzymes. The relationship between renal dysfunction detected by these sensitive tests and the future development of chronic renal disease remains uncertain. Epidemiologic studies have shown an association between blood lead levels and blood pressure, and hypertension is a cardinal feature of lead nephropathy. Evidence for increased body lead burden is a prerequisite for the diagnosis of lead nephropathy. Blood lead levels are a poor indicator of body lead burden and reflect recent exposure. The EDTA lead mobilization test has been used extensively in the past to assess body lead burden. It is now replaced by the less invasive in vivo X-ray fluorescence for determination of bone lead content.     

Methodological problems in AIDS behavioral research: Influences on measurement error and participation bias in studies of sexual behavior.

An unprecedented number of human sexuality studies have been initiated in response to the acquired immune deficiency syndrome (AIDS) epidemic. Unfortunately, methodological developments in the field of sex research have been slow in meeting the demands of AIDS investigations focusing on the diverse populations at risk for human immunodeficiency virus (HIV) infection (e.g., adolescents, gay men, iv drug users, ethnic minorities, elderly transfusees). In this article the authors review and integrate current literature on measurement error and participation bias in sex research, with an emphasis on collecting sexual information in the context of AIDS. The relevance of these findings for AIDS-related sex research is discussed, and recommendations are made to guide future investigations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effective outcomes management in occupational and environmental health

In the final analysis, outcomes management is about changing behavior, specifically in the occupational and environmental health practitioner's communication process and practice patterns and in the workers' prevention and compliance behavior. Outcomes management is also about quantifying results, establishing occupational and environmental health performance benchmarks, developing a best practices model and asking even more questions. As health care embraces the use of outcomes in evaluating its effectiveness, similar developments can be anticipated in occupational and environmental health. While occupational and environmental health outcomes management is still in its infancy, nurses in the workplace are well positioned to "shape it" into a useful tool that meets the needs of all the various practice settings. As nurses in the workplace begin to evaluate, report, and benchmark results, measurement tools will be refined, data bases will grow and new, useful benchmarks will be established. Because occupational and environmental health programs usually operate as part of a larger business unit, nurses in the workplace are continually faced with the challenge of ensuring that corporate programs including workers' compensation, health and disability benefit programs, vaccination programs, injury prevention, and health promotion or wellness programs are delivered in an efficient and cost-effective manner and that the expected outcomes are achieved. Effective outcomes management programs are the vehicles to effective goal achievement.     

DNA extraction and stability for epidemiological studies

An outbreak of food poisoning involving most autonomous Spanish communities was detected in the first half of 1994. The causative food was infant formula milk contaminated by lactose-fermenting Salmonella virchow. It was not possible to isolate the causative strain from the manufacturer's facilities. During the same period of time, there was a significant increase in lactose-non-fermenting Salmonella virchow strains compared with the same period in previous years. Simultaneously, lactose-non-fermenting strains were recovered from clinical samples from children and from some milk samples that were involved in the outbreak. Therefore, it was speculated that the outbreak might be more extensive than initially thought. The following epidemiological markers were used for typing the Salmonella virchow strains involved in the outbreak: (i) phage typing: (ii) ribotyping, using a set of 20 different endonucleases: and (iii) pulsed-field gel electrophoresis, using three different endonucleases. The most useful markers for this serotype were phage typing and pulsed-field gel electrophoresis, since ribotyping was not able to distinguish all strains tested. The results obtained revealed that the outbreak was caused by at least two strains: one presenting phage type 4-4a and pulsed-field patterns A1 or A2 and L+ or L-, and another presenting phage type 2 and pulsed-field patterns A1 or A2 and L+ or L-. The results indicate that the outbreak was more extensive than initially thought and that the Virchow serotype is very clonal in Spain.