Biomedical subjects

D H Garabrant

Publications and source records attributed to D H Garabrant.

At least 37 records · Page 2Linked to original sources

PubMed1994

Exposure to magnetic fields among electrical workers in relation to leukemia risk in Los Angeles County.

To address the hypotheses that electrical workers are exposed to higher magnetic fields and are at higher risk of leukemia than nonelectrical workers, we performed a registry-based case-control study among men aged 20-64 years with known occupation who were diagnosed with cancer in Los Angeles County between 1972 and 1990. Controls were men with cancers other than those of the central nervous system or leukemia. Magnetic field measurements on workers in each electrical occupation and in a random sample of occupations presumed to be nonelectrical were used to estimate magnetic field exposures for each occupation. Among men in electrical occupations, 121 leukemias were diagnosed. With the exception of electrical engineers, magnetic field exposures were higher among workers in electrical occupations than in nonelectrical occupations. A weakly positive trend in leukemia risk across average occupational magnetic field exposure was observed (odds ratio [OR] per 10 milligauss increase in average magnetic field = 1.2, 95% confidence interval [CI] 1.0-1.5). A slightly stronger association was observed for chronic myloid leukemia, although only 28 cases occurred among electrical workers (OR 10 milligauss increase = 1.6, 95% CI = 1.2-2.0). The results were not materially altered by adjustment for exposure to several agents known or suspected to cause leukemia. Although not conclusive, these results are consistent with findings from studies based on job title alone that electrical workers may be at slightly increased risk of leukemia.

Adult↗

PubMed1994

Acute and chronic respiratory effects of sodium borate particulate exposures.

This study examined work-related chronic abnormality in pulmonary function and work-related acute irritant symptoms associated with exposure to borate dust in mining and processing operations. Chronic effects were examined by pulmonary function at the beginning and end of a 7-year interval. Time-specific estimates of sodium borate particulate exposures were used to estimate cumulative exposure during the study interval. Change in pulmonary function over the 7 years was found unrelated to the estimate of cumulative exposure during that interval. Exposure-response associations also were examined with respect to short-term peak exposures and incidence of five symptoms of acute respiratory irritation. Hourly measures of health outcome and continuous measures of particulate exposure were made on each subject throughout the day. Whenever a subject reported one of the irritant symptoms, a symptom intensity score was also recorded along with the approximate time of onset. The findings indicated that exposure-response relationships were present for each of the specific symptoms at several symptom intensity levels. The associations were present when exposure was estimated by both day-long and short-term (15-min) time-weighted average exposures. Associations persisted after taking account of smoking, age, and the presence of a common cold. No significant difference in response rate was found between workers exposed to different types of sodium borate dusts.

Adult↗

PubMed1994

Occupational cancer.

Occupational exposures are important contributors to the total burden of cancer in the United States. No histologic features distinguish occupational cancer from that due to other causes. The IARC provides a systematic framework for evaluating the evidence linking occupational exposures to human cancer and publishes summary monographs which detail the strength of evidence for approximately 732 agents evaluated to date. These monographs are one of the most reliable reference sources for practitioners who must answer questions regarding cancer risk to working populations. The diagnosis of occupational cancer must be based on a systematic approach in which the diagnosis of cancer is confirmed, the exposures of the patient are defined and quantified, and the scientific evidence regarding the risk from such exposures is evaluated. Cancer screening programs in work settings are difficult to justify based on scientific principles and must be adapted to the circumstances of exposure and to meet legal requirements for medical surveillance, if they are to be performed at all. Investigation of cancer clusters often presents a difficult scientific challenge, which requires careful case ascertainment, calculations of risk based on an appropriate reference population, identification of distant past exposures, and a search for common elements among the cases. Negative and equivocal findings are common, and it is important for investigators to be able to demonstrate the scientific rigor of their approach in resolving these issues.

Carcinogens↗

PubMed1992

DDT and related compounds and risk of pancreatic cancer.

BACKGROUND: A cohort mortality study among 5886 chemical manufacturing workers was completed in 1987 and showed increased mortality due to pancreatic cancer. PURPOSE: We conducted a nested case-control study of pancreatic cancer among these chemical manufacturing workers to identify risk factors for this disease. METHODS: Twenty-eight verified cases of pancreatic cancer and 112 matched controls were studied. Next of kin of each subject were interviewed to determine lifestyle factors, including tobacco, alcohol, and coffee consumption. Written work records and interviews with co-workers were used to determine chemical exposures at the plant under study. RESULTS: DDT was associated with pancreatic cancer (risk ratio [RR] for ever exposed compared with never exposed = 4.8; 95% confidence interval = 1.3-17.6). Among subjects who had a mean exposure to DDT of 47 months, the risk was 7.4 times that among subjects with no exposure. Two DDT derivatives, Ethylan and DDD, were additionally associated with pancreatic cancer (RR = 5.0 and 4.3, respectively); exposures to these two chemicals were correlated, and it was not possible to determine whether each acted independently of the other. Smoking was identified as an independent risk factor, but controlling for smoking (and other potential confounders) in the analyses did not appreciably alter the risks seen for DDT, DDD, or Ethylan. CONCLUSIONS: Exposure to DDT was associated with pancreatic cancer. The association was not explained by exposure to lifestyle factors or other chemicals, and risk increased with both duration of exposure and latency since first exposure. IMPLICATIONS: These results may indicate that DDT can cause pancreatic cancer in humans under circumstances of heavy and prolonged exposure.

Case-Control Studies↗

PubMed1992

Asbestos and colon cancer: lack of association in a large case-control study.

Previous studies linking exposure to asbestos with human colon cancer have used mortality rather than incidence as their endpoint and have neither assessed nor controlled for confounding by diet, genetic factors, or other risk factors for colon cancer. A case-control study of 746 histologically confirmed cases of colon cancer and 746 matched neighborhood controls was conducted in Los Angeles County, California. In univariate analyses of the 419 male pairs, a weak association was found between asbestos exposure and colon cancer (odds ratio (OR) = 1.16, 95% confidence interval (CI) 0.80-1.69). When confounding by family history of large bowel cancer, diet, body weight, and physical activity was controlled, there was no association between colon cancer and exposure to asbestos among males (OR = 0.99, 95% CI 0.66-1.50). When asbestos exposure was restricted to occurrences preceding diagnosis by more than 15 years, there was no clear association between such exposure and colon cancer, either before (OR = 1.14, 95% CI 0.76-1.70) or after confounding was controlled (OR = 0.93, 95% CI 0.60-1.44). Further analyses by frequency and duration of exposure failed to show any association between asbestos and risk of colon cancer, but did show a consistent pattern of confounding by nonoccupational factors that, when controlled, invariably produced a weak protective effect of asbestos exposure. Among the 327 female pairs, only 6 cases and 11 controls reported asbestos exposure (OR = 0.55, 95% CI 0.20-1.48), and there was no evidence of risk increasing as the frequency or duration of exposure increased. This study suggests not only that occupational exposure to asbestos is not a risk factor for colon cancer in the general population of Los Angeles, but also that observed associations between asbestos and colon cancer should not be interpreted as causal unless confounding by nonoccupational factors has been evaluated and controlled.

Aged↗

PubMed1991

Occupational asbestos exposure and mesothelioma risk in Los Angeles County: application of an occupational hazard survey job-exposure matrix.

We evaluated the newly available National Institute for Occupational Safety and Health (NIOSH) National Occupational Hazard Survey (NOHS) job exposure matrix (JEM) by considering mesothelioma risk from asbestos exposure. We applied this system (NOHS-JEM) to the Los Angeles County Cancer Surveillance Program (CSP) to see how many cancer cases could be assigned asbestos exposure and how asbestos exposure affected mesothelioma risk. Using the same CSP data, our "experts" classified asbestos exposure simply by occupation and industry. Both exposure classifications were divided into low and high; the NOHS-JEM by the number of exposed people per couplet, and ours by judgements of intensity. Odds ratios (OR) for mesothelioma risk for low and high asbestos exposure for the NOHS-JEM were 2.0 (95% C.I. 1.2-3.4) and 2.5 (95% C.I. 1.2-4.8). For ours, corresponding risks were 1.6 (95% C.I. 1.1-2.4) and 6.3 (95% C.I. 2.5-15.1). Our system was able to assign more cases to couplets then the NOHS-JEM (35,895 to 22,369). Three limitations of the NOHS-JEM were that many occupation-industry couplets were not classified at all, many couplets associated with past asbestos exposure (before the 1972-1974 NOHS survey) were not classified as asbestos exposure, and no assessment of intensity was made. These limitations may apply to other exposures and should be carefully considered before the NOHS-JEM is applied to other case-control studies.

Adolescent↗

PubMed1990

Occupational and other non-dietary risk factors for nasopharyngeal carcinoma in Guangzhou, China.

We conducted interviews on 306 histologically confirmed incident cases of nasopharyngeal carcinoma (NPC) occurring in residents of Guangzhou City, China, who were under the age of 50, and an equal number of age-, sex-, and neighborhood-matched controls. We also interviewed 110 mothers of patients under 45 and 139 mothers of controls who were matched to patients under age 45, to obtain information on childhood exposures of study subjects. Occupational exposure to products of combustion (RR = 2.4, p = 0.001) and cotton dust (RR = 0.3, P = 0.01) was independently related to risk of NPC. Use of tobacco products showed a moderate association with NPC; a lifetime exposure of 30+ pack-year equivalents conferred a 2-fold increased risk. A history of chronic ear or nose condition (rhinitis, sinusitis, nasal polyp, otitis media) was another risk factor for NPC (RR = 2.2, p less than 0.0005), and 18 cases compared to 3 controls had a first-degree relative with NPC (RR = 6.0, p = 0.001).

Adult↗

PubMed1989

A case-control study of occupational and dietary factors in colorectal cancer in young men by subsite.

With the hope that exposures responsible for colorectal cancer might be especially obvious among those in whom it develops early, 147 men with colorectal carcinomas first diagnosed between the ages of 25 and 44 years were compared to neighborhood controls. Physical activity on the job was protective for tumors located in the transverse and descending portions of the colon. Rectal cancer and to a lesser extent sigmoid cancers were associated with jobs in which dusts or fumes were inhaled, especially if those jobs were held for long periods in young adulthood. While risk for rectal cancer did not seem to be limited to any particular type of dust or fume, the excess risk was strongest for wood and metal dusts. Consumption of fruits and vegetables and a preference for whole grain breads were protective for colon but not rectal cancers, while consumption of deep fried foods and barbecued/smoked meats increased risk at specific subsites. Beef intake, alcohol consumption, and cigarette smoking appeared to play little or no role at any subsite.

Adenocarcinoma↗

PubMed1989

Occupational exposures of parents of children with acute nonlymphocytic leukemia: a report from the Childrens Cancer Study Group.

The Childrens Cancer Study Group conducted a case-control study of occupational exposures of parents of 204 children (under 18 yr of age) with acute nonlymphoblastic leukemia. The most consistent finding was an association of acute nonlymphoblastic leukemia risk with pesticide exposure. Controls matched by date of birth and race were obtained through random digit dialing. Odds ratio (OR) for paternal pesticide exposure in jobs held for longer than 1000 days was 2.7 (95% confidence interval, 1.0 to 7.0; trend, P = 0.06), and seven case mothers and no control mothers had prolonged exposure (trend, P = 0.008). Risk estimates for parental pesticide exposure were substantially increased for children under age 6 at diagnosis (OR for prolonged exposure to either parent = 11.4; trend, P = 0.003) and for those with myelomonocytic and monocytic subtypes (OR, 13.6; trend, P = 0.007). Moreover, there were significantly elevated risks for direct exposure of the child to pesticides in the household (OR for exposure most days = 3.5; trend, P = 0.04) and for maternal exposure to household pesticides at the time of pregnancy (eight case mothers versus no controls for exposure most days; trend, P = 0.05). Paternal exposures to solvents (OR, 2.1; P = 0.003) and petroleum products (OR, 2.4; P = 0.002) were reported more commonly for cases than controls. Other occupational exposures reported significantly more often by case parents were paternal exposure to plastics or lead and maternal exposure to paints and pigments, metal dusts, and sawdust. These data provide further evidence for a role of occupational risk factors in the etiology of childhood cancer.

Adolescent↗

PubMed1989

Prospective study of respiratory effects of formaldehyde among healthy and asthmatic medical students.

We conducted a prospective evaluation of pulmonary function and respiratory symptoms among 103 medical students exposed to formaldehyde over a 7-month period to determine the incidence of bronchoconstriction and respiratory symptoms in response to exposure. Time-weighted average formaldehyde exposures were generally less than 1 part per million (ppm) and peak exposures were less than 5 ppm. Acute symptoms of eye and upper respiratory irritation were significantly associated with exposure. There was no pattern of bronchoconstriction in response to exposure after either 2 weeks or 7 months. Twelve subjects had a history of asthma; they were no more likely to have symptoms of respiratory irritation or changes in pulmonary function than those without such a history. These findings are consistent with previous case reports that indicate exposure to formaldehyde vapor at levels that are commonly encountered in occupational and residential settings do not commonly cause significant bronchoconstriction, even among subjects with preexisting asthma.

Adult↗

PubMed1989

Fatal occupational injuries in California, 1972-1983.

Prior reports have indicated that the crude incidence of fatal occupational accidents in California has substantially declined since at least 1972. We tested the hypothesis that this observation was an artifact of demographic shifts in the workforce towards lower-risk age groups and industries. Review of worker's compensation data from 1972 to 1983 identified 2,483 fatal injuries among males. Crude rates declined by an average of 7.0% annually (p less than .005). Age and industry adjustment reduced this decline to 6.7% annually, but the trend was still significant (p less than .005). Thus, the decline in fatal injury rates is not artifactual and will require further study to explain. In a separate analysis, age-specific death rates were found to follow a bimodal pattern in most industries with the highest rates observed at the extremes of age. These results conflict with those of several previous studies. However, these studies did not adjust for the prevalence of part-time work schedules among younger employees.

Accidents, Occupational↗

PubMed1989

Case-control study of lung cancer in Los Angeles county welders.

A case-control study of lung cancer in white male welders was undertaken to investigate possible environmental and occupational causes of a 50% excess of lung cancer observed in this occupational group. The subjects were identified from a population-based cancer registry in Los Angeles County. A standardized questionnaire was administered to either subjects or proxy informants of 90 lung cancer cases and 116 non-lung-cancer controls. Significantly increased risks of lung cancer were associated with tobacco smoking (odds ratio 7.6, p less than .005) and shipyard welding with at least a 10-year latency since first exposure (odds ratio 1.7, p less than .05). Although there were elevated risks associated with some specific welding processes, none were statistically significant. Control subjects were more likely to have had exposure to confined-space welding (odds ratio 0.6, 95% CI = 0.3-1.2), and this association was greatest where there had been at least a 20-year latency since first exposure (0.5, 95% CI = 0.3-1.0). We conclude that the excess of lung cancer in this welding population is contributed to by a higher frequency of smoking and probable exposure to asbestos in shipyards. Other factors may be important, but probably because of limited power and reliance on proxy information, this study failed to detect other statistically significant risks.

Adult↗

PubMed1988

Tobacco, alcohol, diet, occupation, and carcinoma of the esophagus.

Information on occupation, smoking, food and beverage consumption, and medical history were compared between 275 incident cases of carcinoma of the esophagus and 275 neighborhood controls who were matched to the cases on age (within 5 years), race, and sex. Tobacco use, mainly cigarette smoking, was a significant risk factor for carcinoma of the esophagus. Ex-smokers of cigarettes showed a reduced risk relative to those who continued to smoke, and current smokers of two or more packs per day displayed a higher risk than those who smoked less. Alcohol consumption was another significant risk factor for carcinoma of the esophagus; there was a highly significant trend with average daily dose of ethanol. Relative to controls, cases also consumed significantly more fried bacon or ham, less fresh fruits and raw vegetables, and were more likely to prefer white than whole grain bread. Finally, there was a significant association between carcinoma of the esophagus and long-term occupational exposure to metal dust; this association was largely confined to the lower one-third section of the esophagus.

Alcohol Drinking↗

PubMed1988

Mortality of aircraft manufacturing workers in southern California.

A retrospective cohort mortality study was conducted among men and women employed for four or more years, between 1958 and 1982, at an aircraft manufacturing company in San Diego County. Specific causes of death under investigation included cancer of the brain and nervous system, malignant melanoma, and cancer of the testicle, which previous reports have suggested to be associated with work in aircraft manufacturing. Follow-up of the cohort of 14,067 subjects for a mean duration of 15.8 yr from the date of first employment resulted in successful tracing of 95% of the cohort and found 1,804 deaths through 1982. Standardized mortality ratios (SMRs) were calculated based on U. S. national mortality rates and separately based on San Diego County mortality rates. Mortality due to all causes was significantly low (SMR = 75), as was mortality due to all cancer (SMR = 84). There was no significant excess of cancer of the brain, malignant melanoma, cancer of the testicle, any other cancer site, or any other category of death. Additional analyses of cancer sites for which at least ten deaths were found and for which the SMR was at least 110 showed no increase in risk with increasing duration of work or in any specific calendar period. Although this study found no significant excesses in cause-specific mortality, excess risks cannot be ruled out for those diseases that have latency periods in excess of 20 to 30 yr, or for exposures that might be restricted to a small proportion of the cohort.

Aircraft↗

PubMed1988

Myelogenous leukemia and electric blanket use.

In a case-control study of adult acute and chronic myelogenous leukemia in Los Angeles County, we tested the hypothesis that excess exposure to electromagnetic fields from electric blankets was associated with risk of leukemia. We did this by studying 116 cases of acute myelogenous leukemia (AML) and 108 cases of chronic myelogenous leukemia (CML) along with matched neighborhood controls. The cases and controls were queried as to electric blanket use and the risks computed. For AML the risk was 0.9 (95% CI 0.5-1.6) and for CML the risk was 0.8 (95% CI 0.4-1.6). Cases did not differ from controls by duration of use, year of first regular use, year since last use, or socioeconomic status. Our best estimates of exposure indicate that electric blanket use increases overall exposure to electric fields by less than 50% and magnetic fields by less than 100%. We conclude that there is no major leukemogenic risk associated with electric blanket use in Los Angeles County.

Adult↗

PubMed1988

Adenocarcinoma of the stomach and exposure to occupational dust.

The authors studied 1,342 cases of adenocarcinoma of the stomach identified by a population-based cancer registry in Los Angeles County, California. The cases were males aged 20-64 years first diagnosed between 1972 and 1982. To determine whether exposure to occupational dust increased the risk of developing stomach cancer, occupational titles were rated for the likelihood of exposure to various kinds of dust. Men who worked in dusty jobs had a risk for developing stomach cancer 1.3 times that of unexposed men (95% confidence interval = 1.2-1.4). The association of exposure to dust with stomach cancer was stronger at higher levels of exposure. The risk was not uniform throughout the stomach: the highest risk (1.8 times that of unexposed men) was found for the antrum/pylorus. At that site, exposure to mineral dust carried the greatest risk for cancer (3.7 times the risk for unexposed men). The highest risks from dust exposure were observed in blacks. Risk was related to race, socioeconomic status, and immigrant status, but these factors did not entirely explain the association with dust exposure. The observed relation between dust exposure and stomach cancer is consistent with results of previous mortality and case-control studies of cancer in men who worked in dusty occupations. Ingested dust may be one factor in the etiology of adenocarcinoma of the stomach.

Adenocarcinoma↗

PubMed1987

Respiratory effects of cotton dust exposure in the cotton garnetting industry.

We measured exposures to total dust, vertically elutriated dust, and endotoxin and studied acute pulmonary responses among 128 workers in the cotton garnetting and mattress assembly industries. Previous studies in this segment of industry have not characterized endotoxin exposures or related them to pulmonary responses. The median 8-hour time-weighted average total dust was 0.72 mg/m3, the median vertically elutriated dust was 0.22 mg/m3, and the median endotoxin concentration was 5.2 ng/m3. Ten percent of the subjects reported chest tightness or dyspnea on Mondays. Thirteen percent of the subjects reported symptoms of chronic bronchitis. Although there was no relationship between changes in pulmonary function across the workshift and either total dust, vertically elutriated dust, or endotoxin exposure, 13% of the subjects had greater than 5% decrements in FEV1 over the workshift.

Adult↗

PubMed1987

Abnormalities of pulmonary function and pleural disease among titanium metal production workers.

The authors conducted a cross-sectional survey of respiratory disease among 209 titanium metal production workers. Work in areas where there was exposure to titanium tetrachloride and titanium dioxide particulates was associated with reductions in ventilatory capacity. Pleural disease (plaques and diffuse thickening) was present in the chest radiographs of 17% of the subjects and was associated with the duration of work in titanium manufacturing. It was also associated with past asbestos exposure. After control for asbestos exposure, it remained associated with titanium manufacturing. The findings are consistent with the hypothesis that titanium tetrachloride and titanium dioxide particulates may be associated with a reduction in ventilatory capacity and that the overall process of titanium manufacturing may be associated with unexpected pleural disease.

Adult↗