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D Loomis

Publications and source records attributed to D Loomis.

At least 37 records · Page 2Linked to original sources
PubMed2000

Case-cohort analysis of brain cancer and leukemia in electric utility workers using a refined magnetic field job-exposure matrix.

BACKGROUND: The potential association between occupational electric and magnetic field exposure and cancer is well documented in the literature, but there is uncertainty regarding a causal relation. METHODS: Using data from a completed cohort study, we sought to refine the job-exposure matrix in a case-cohort analysis by regrouping jobs into more homogeneous groups, but without making additional measurements. From the original cohort, we selected the 164 men who died of leukemia, 145 men who died of brain cancer, and a random subcohort of 800 men (0.6% of the cohort). Erroneous job assignments were corrected and job groups were subdivided based on differences in work environments or tasks performed. RESULTS: Magnetic field exposure remained unrelated to leukemia mortality and positively associated with brain cancer mortality based on both cumulative and average magnetic field indices. Although not monotonic across the middle intervals, increased risk of brain cancer was found in relation to career exposure, with risk ratios of 1.8 (95% CI = 0.7-4.7) and 2.5 (95% CI = 1.0-6.3) in the uppermost categories for cumulative and average exposure, stronger for exposure 2-10 years past. CONCLUSIONS: Improvements in exposure assignment based only on reassignment of job titles to occupational categories had little impact on the measured associations of magnetic fields with leukemia or brain cancer.

Brain Neoplasms↗
PubMed2000

Mortality from six work-related cancers among African Americans and Latinos.

BACKGROUND: Ethnic minorities have been omitted from many occupational health studies, despite their substantial contributions to the labor force and documented cases of high exposures in some settings. To describe the occurrence of potentially work-related cancers among African American and Latino Workers, we conducted an epidemiologic study based on death certificate data. METHODS: Data were obtained from 21 states during 1985-1992. Directly adjusted proportionate mortality ratios (PMRs) and standardized mortality rate ratios (SRRs) for ages 20-64 years were computed for cancers of the lung, nasal cavity, pleura, and peritoneum, malignant melanoma and leukemia using the mortality data and population counts from the 1990 census. RESULTS: Proportionate mortality was generally low for both groups, but African Americans had higher than expected mortality rates for leukemia and cancers of the lung, nasal cavity, and peritoneum. Industry-specific analyses indicate excess leukemia among African American men in the rubber industry (PMR 2.08, 95% confidence interval (CI) 1.29 - 3.35), Latino men in textile (PMR 2. 31, 95% CI 0.81 - 5.13) and wood industries (PMR 2.03, 95% CI 0.81 - 5.13), and Latino women in the chemical industry (PMR 2.18, 95% CI 0.59 - 8.10), among other findings. Excess cancer of the pleura and peritoneum was observed among workers with a variety of usual occupations, consistent with widespread exposure to asbestos. CONCLUSIONS: This study demonstrates the utility of surveillance data bases for generating basic epidemiologic information on historically neglected workers. Leads about specific workplace exposure can be followed up in more detailed studies.

Adult↗
PubMed2000

Exposure to electromagnetic fields and suicide among electric utility workers: a nested case-control study.

OBJECTIVE: To examine mortality from suicide in relation to estimated exposure to extremely low-frequency electromagnetic fields in a cohort of 138,905 male electric utility workers. METHODS: Case-control sampling, which included 536 deaths from suicide and 5, 348 eligible controls. Exposure was classified based on work in the most common jobs with increased exposure to magnetic fields and indices of cumulative exposure to magnetic fields based on a measurement survey. RESULTS: Suicide mortality was increased relative to work in exposed jobs and with indices of exposure to magnetic fields. Increased odds ratios (ORs) were found for years of employment as an electrician (OR, 2.18; 95% confidence interval [CI], 1.25-3.80) or line worker (OR, 1.59; 95% CI, 1.18-2.14), whereas a decreased OR was found for power plant operators (OR, 0.67; 95% CI, 0.33-1.40). A dose-response gradient with exposure to magnetic fields was found for exposure in the previous year, with a mortality OR of 1.70 (95% CI, 1.00-2.90) in the highest exposure category. Stronger associations, with ORs in the range of 2.12 to 3.62, were found for men younger than 50 years. CONCLUSIONS: These data provide evidence for an association between occupational electromagnetic fields and suicide that warrants further evaluation. A plausible mechanism related to melatonin and depression provides a direction for additional laboratory research and epidemiologic evaluation.

Adult↗
PubMed2000

Exposure to electromagnetic fields and suicide among electric utility workers: a nested case-control study.

OBJECTIVES: This nested case-control study examines mortality from suicide in relation to estimated exposure to extremely low frequency electromagnetic fields (EMFs) in a cohort of 138,905 male electric utility workers. METHODS: Case-control sampling included 536 deaths from suicide and 5348 eligible controls. Exposure was classified based on work in the most common jobs with increased exposure to magnetic fields and indices of cumulative exposure to magnetic fields based on a measurement survey. RESULTS: Suicide mortality was increased relative to work in exposed jobs and with indices of exposure to magnetic fields. Increased odds ratios (ORs) were found for years of employment as an electrician (OR 2.18; 95% confidence interval (95% CI) 1.25 to 3.80) or lineman (OR 1.59; 95% CI 1.18 to 2.14), whereas a decreased OR was found for power plant operators (OR 0.67; 95% CI 0.33 to 1.40). A dose response gradient with exposure to magnetic fields was found for exposure in the previous year, with a mortality OR of 1.70 (95% CI 1.00 to 2.90) in the highest exposure category. Stronger associations, with ORs in the range of 2.12-3.62, were found for men <50 years of age. CONCLUSION: These data provide evidence for an association between occupational electromagnetic fields and suicide that warrants further evaluation. A plausible mechanism related to melatonin and depression provides a direction for additional laboratory research as well as epidemiological evaluation.

Adolescent↗
PubMed2000

[Cancer mortality among Brazilian Navy personnel].

OBJECTIVE: To identify differences in cancer proportionate mortality among male servicemen of the Brazilian Navy when compared to a referent population and to detect potential occupational risk factors. METHODS: Cancer proportionate mortality was estimated using death certificates and occupational histories of Brazilian navy servicemen aged 19 or more in the period of 1991 to 1995. The population of Rio de Janeiro (Brazil) was chosen as referent group because this city concentrates 70% of all Navy servicemen. RESULTS: Servicemen are more likely to die from brain neoplasm (age-adjusted cancer proportionate mortality ratio - ACPMR=339.27), prostate cancer (ACPMR=135.04), and non-Hodgkin lymphoma (ACPMR=152.28) than the referent population. Health-related occupations show an excess of brain neoplasm (ACPMR=2.7, 95% confidence interval, CI: 1.1-6.5) and liver cancer (ACPMR=2.9; 95% CI: 1.1-7.8); colon-rectal cancer was higher among officials of the Army Corp and other administrative occupations (ACPMR=2.4, 95% CI: 1.3-4.5); larynx cancer (ACPMR=2.3, 95% CI; 1.1-5.0) is more common among men working in maintenance and repair occupations. CONCLUSIONS: In this study, servicemen of the Brazilian Navy Force have a distinct cancer mortality profile from the general reference population. Risk factors for cancer need to be further evaluated, by using more specific diagnosis and occupational-related exposure data.

Adult↗
PubMed1999

Fatal occupational injuries among electric power company workers.

Surveillance data suggest high rates of electrocutions and fatal falls among workers in electric utility companies, who may be exposed to electric current, heights, flammable agents, and frequent motor vehicle travel. To characterize the occurrence of fatal injuries among electric utility workers, we studied workers in five electric power companies in the United States. A cohort of 127,129 men hired between 1950 and 1986 was followed through 1988. Injuries at work were identified through manual review of death certificates. The occurrence of occupational injuries was analyzed with directly adjusted rates and Poisson regression. The overall rate of fatal occupational injuries was 13.20 per 100,000 person-years (n = 192), with 76% due to electric current, homicide, and falls from heights. Deaths were concentrated in a few groups with elevated injury rates, notably linemen (rate ratio (RR) 3.33), electricians (RR 2.79), and painters (RR 3.27). Occupations requiring daily work on elevations or frequent, direct contact with energized electrical equipment experienced markedly higher rates of fatal injury from falls and electrocutions with rate ratios of 21.8 (95% confidence interval (CI) 11.4-41.5) and 16.7 (95% CI 6.6-42.6), respectively, independent of worker age and seniority. Although fatal injury rates in this industry have declined in recent decades, significant numbers of deaths still occur. Based on the premise that all injuries are preventable, a need for continued vigilance and efforts at prevention is indicated.

Accidental Falls↗
PubMed1999

Refinements in magnetic field exposure assignment for a case-cohort study of electrical utility workers.

This study examined the effect of refinements in exposure assignment on annual and career exposure to 60 Hz magnetic fields, using all deaths from brain cancer (145) and leukemia (164) and a random sample of 800 workers from a cohort of 138,905 men. Reassessment of 1060 job titles in the measurement database generated 20 subcategories in addition to 28 occupational categories used in the original cohort mortality study. Furthermore, previously misclassified jobs were corrected. The complete work history of each sub-cohort member was re-examined. Original and refined average annual exposures were 0.086 and 0.088 microT, respectively. The average career cumulative exposures were 1.40 and 1.44 microT-years, respectively. Spearman correlation coefficients between the original and refined methods across the companies were 0.81 for annual exposure and 0.93 for career cumulative exposure. 23% of the workers were assigned to another exposure ranking after refinement, but 85% of these moved to an adjacent group, suggesting that the differences in exposure ranking are small. The results of this study indicate that refinements have modest influence on the average annual and career exposures. However, the refinements may only change a very rough exposure assessment into one that is slightly less crude. The proportion of workers assigned to another exposure ranking indicated that nondifferential exposure misclassification in the original cohort mortality study may have occurred. Implications of these changes for the risk estimates of brain cancer and leukemia cases will to be examined.

Adult↗
PubMed1999

Air pollution and infant mortality in Mexico City.

Historic air pollution episodes of the 1950s led to acute increases in infant mortality, and some recent epidemiologic studies suggest that infant or child mortality may still result from air pollution at current levels. To investigate the evidence for such an association, we conducted a time-series study of infant mortality in the southwestern part of Mexico City in the years 1993 to 1995 using mortality data from death registrations and air pollution measurements from a monitoring station we operated. Excess infant mortality was associated with the level of fine particles in the days before death, with the strongest association observed for the average concentration of fine particles during the period 3 to 5 days previously: a 10-microg m(-3) increase in the mean level of fine particles during these 3 days was associated with a 6.9% excess of infant deaths (95% confidence interval 2.5-11.3%). Infant mortality was also associated with the levels of nitrogen dioxide and ozone 3 to 5 days before death, but not as consistently as with particles.

Air Pollution↗
PubMed1998

Mortality and ambient fine particles in southwest Mexico City, 1993-1995.

++Epidemiologic studies have focused attention on the health effects of fine particulate air pollutants <2.5 microm in diameter (PM2.5). To further characterize the potential effects of fine particles, we investigated the relationship of air pollution to mortality in Mexico City during 1993-1995. The concentration of PM2.5 was measured on a 24-hr integrated basis; concentrations of NO2 and ozone were measured hourly and reduced to 24-hr means. Daily mortality was determined from death registration records, and Poisson regression was used to model daily death counts as a function of air pollutant levels on the same and previous days, while controlling for temperature and periodic cycles. Without taking other air pollutants into account, a 10 microg/m3 increase in the level of PM2.5 was associated with a 1.4% increase in total mortality, both on the current day and 4 days after exposure [95% confidence interval (CI), 0.2-2.5]. An equivalent increase in PM2.5 was also associated with somewhat larger excesses of deaths among people over 65 years of age and from cardiovascular and respiratory causes, which occurred after a lag of 4 days. The mean concentration of ozone over a 2-day period was associated with a 1.8% increase in mortality from cardiovascular diseases. NO2 was not consistently related to mortality. Fine particles had an independent effect on mortality when modeled simultaneously with other pollutants, and the association of ozone with cardiovascular mortality was strengthened after adjusting for NO2 and PM2.5. These results support previous findings that urban air pollution at current levels leads to excess mortality and suggest that fine particles may play a causal role in producing that excess.

Adolescent↗
PubMed1998

Association between air pollution and intrauterine mortality in São Paulo, Brazil.

The associations among daily counts of intrauterine mortality and pollutant concentrations (NO2, SO2, CO, O3, and particulate matter (3/4)10 microm) were investigated for the period ranging from January 1991 to December 1992 in the city of São Paulo, Brazil. We used Poisson regression techniques, adjusted for season and weather. The association between intrauterine mortality and air pollution was strong for NO2 (coefficient = 0.0013/ microg/m3; p<0.01) but lesser for SO2 (coefficient = 0.0005/ microg/m3; p<0.10) and CO (coefficient = 0.0223/ppm; p<0.10). A significant association was observed when an index that combined these three pollutants was considered in the models instead of considering each pollutant individually (p<0.01). These associations exhibited a short time lag, not over 5 days. In addition, some evidence of fetal exposure to air pollution was obtained by disclosing a significant association between the levels of carboxyhemoglobin of blood sampled from the umbilical cord and ambient CO levels in children delivered by nonsmoking pregnant women in the period from May to July 1995. Our results suggest that air pollution in São Paulo may promote adverse health effects on fetuses.

Adult↗
PubMed1998

Race and the risk of fatal injury at work.

OBJECTIVES: This study examined employment patterns of African-American and White workers and rates of unintentional fatal injuries, METHODS: Medical examiner and census data were used to compare occupational fatality rates for African Americans and Whites in North Carolina and to adjust for racial differences in employment patterns. RESULTS: African Americans' occupational fatality rate was higher by a factor of 1.3 to 1.5. Differences in employment structure appear to explain much of this disparity. However, the fatality rate for African-American men would have been elevated even if they had had the same employment patterns as White men. CONCLUSIONS: inequalities in access to the labor market, unequal distribution of risk within jobs, and explicit discrimination are all potential explanations for racial disparities in occupational injury mortality. These conditions can be addressed through a combination of social and workplace interventions, including efforts to improve conditions for the most disadvantaged workers.

Accidents, Occupational↗
PubMed1997

Fatal agricultural injuries in North Carolina by race and occupation, 1977-1991.

Medical examiner reports and death certificates were reviewed for all fatal agricultural injuries (n = 228) that occurred on-the-job in North Carolina between 1977 and 1991. Data were collected on the decedents' age, gender, race, data and time of injury, means of injury, and occupation. Annual workforce estimates were derived from the 1980 and 1990 US Census of the Population. Overall, 54% of the fatal injuries were due to tractors. Farmers who suffered fatal injuries tended to be older (median age = 56 years) and Caucasian (87%), while farm workers who died on the job were younger (median age = 35 years) and more often African-American (60%). The crude mortality rate for farmers was 38 per 100,000 worker-years; the crude rate for farm laborers was 16 per 100,000 worker-years. Age-adjusted fatal injury rates were 2.5 times higher among African-American farmers than among Caucasian farmers; furthermore, between 1977 and 1991 the rate of fatal injury among African-American farmers increased an estimated 14.7% per year. African-American farmers in North Carolina have experienced rising rates of fatal injuries at a time when employment in the industry is declining due to consolidation of farm ownership and foreclosures of African-American owned farms. In order to address the growing racial disparity in farm fatalities, efforts need to be made to improve the conditions under which African-American farmers are working.

Accidents, Occupational↗
PubMed1997

Informal jobs: another occupational hazard for women's mental health?

OBJECTIVES: The hypothesis that informal jobs, which imply absence of formal labour contracts, instability and the absence of fringe benefits, are positively associated with psychiatric symptoms was evaluated in a poor urban area of Brazil. METHODS: With data from a cross-sectional study, the association between informal jobs and high number of psychological symptoms was estimated. The study population was composed of 327 women randomly selected from a community in the city of Salvador, Brazil. Women who reported having a job without a formal contract were classified as informal workers. Psychological symptoms were collected through a validated questionnaire, the QMPA. RESULTS: A positive association between informal work and a high number of psychological symptoms was found (crude prevalence ratio = 1.88, 95% confidence interval [CI]: 1.24-2.85). More than 4 hours of housework a day and being a family head were confounders, although adjustment for these variables did not significantly change the results (adjusted prevalence ratio = 1.97, 95% CI: 1.26-3.09). CONCLUSIONS: These findings are suggestive that informal work may be a risk for mental symptoms. Reinforcement of universal labour rights coverage and improvement in housework sharing are recommended.

Adolescent↗
PubMed1997

Intraindividual variability and redundancy of semen parameters.

We analyzed two databases comprising repeated semen analyses of male patients visiting a fertility clinic in the Netherlands to assess intra- and interindividual variability for several semen parameters. We calculated reliability coefficients to estimate the attenuation of the slope if semen parameters are used to predict the probability of conception in regression models. Reliability was lowest for morphology (Population A: R = 0.48, Population B: R = 0.54), but somewhat better for motility (Population A: R = 0.66, Population B: R = 0.71) and count (Population A: R = 0.79, Population B: R = 0.81). Semen concentration had the largest reliability coefficients (Population A: R = 0.84, Population B: R = 0.84). Stimulations using empirical variance components indicated that using semen parameters as endpoints in case-referent studies might substantially underestimate measures of association. The results showed that most semen parameters were just moderately redundant (range: Kappa = 0.28 to Kappa = 0.45); only agreement between concentration and count was substantial (Population A: Kappa = 0.84, Population B: Kappa = 0.80). Hence, epidemiologic studies focusing on male infertility should take into account a variety of parameters.

Analysis of Variance↗
PubMed1997

Cancer mortality among electric utility workers exposed to polychlorinated biphenyls.

OBJECTIVES: To assess whether excess mortality from cancer, malignant melanoma of the skin, and cancers of the brain and liver in particular, is associated with long term occupational exposure to polychlorinated biphenyls (PCBs). METHODS: An epidemiological study of mortality was conducted among 138,905 men employed for at least six months between 1950 and 1986 at five electrical power companies in the United States. Exposures were assessed by panels composed of workers, hygienists, and managers at each company, who considered tasks performed by workers in 28 job categories and estimated weekly exposures in hours for each job. Poisson regression was used to examine mortality in relation to exposure to electrical insulating fluids containing PCBs, controlling for demographic and occupational factors. RESULTS: Neither all cause nor total cancer mortality was related to cumulative exposure to PCB insulating fluids. Mortality from malignant melanoma increased with exposure; rate ratios (RRs) relative to unexposed men for melanoma were 1.23 (95% confidence interval (95% CI) 0.56 to 2.52), 1.71 (0.68 to 4.28) and 1.93 (0.52 to 7.14) for men with < 2000, > 2000-10,000, and > 10,000 hours of cumulative exposure to PCB insulating fluids, respectively, without consideration of latency. Lagging exposure by 20 years yielded RRs of 1.29 (0.76 to 2.18), 2.56 (1.09 to 5.97), and 4.81 (1.49 to 15.50) for the same exposure levels. Mortality from brain cancer was modestly increased among men with < 2000 hours (RR 1.61, 95% CI 0.86 to 3.01) and > 2000-10,000 hours exposure (RR 1.79, 95% CI 0.81 to 3.95), but there were no deaths from brain cancer among the most highly exposed men. A lag of five years yielded slightly increased RRs. Mortality from liver cancer was not associated with exposure to PCB insulating fluids. CONCLUSIONS: This study was larger and provided more detailed information on exposure than past investigations of workers exposed to PCBs. The results suggest that PCBs cause cancer, with malignant melanoma being of particular concern in this industry.

Follow-Up Studies↗