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Biomedical subjects

D A Savitz

Publications and source records attributed to D A Savitz.

At least 55 records · Page 3Linked to original sources
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

Glutathione S-transferases M1, T1, and P1 and breast cancer.

We examined associations for glutathione S-transferases M1 (GSTM1), T1 (GSTT1), and P1 (GSTP1) genotypes and breast cancer in the Carolina Breast Cancer Study, a population-based, case-control study in North Carolina. Odds ratios were close to the null value for each GST locus among African-American women (278 cases and 271 controls) and white women (410 cases and 392 controls), as well as pre- and postmenopausal women. For women with a history of breast cancer in one or more first-degree relatives, odds ratios were 2.1 (95% confidence interval, 1.0-4.2) for GSTM1 null and 1.9 (0.8-4.6) for GSTT1 null genotypes. Among women with a family history, age at diagnosis was significantly earlier for those with the GSTM1 null genotype. We did not observe strong evidence for modification of odds ratios for smoking according to GST genotypes. There was no evidence for combined effects of GSTM1, GSTT1, and GSTP1 genotypes, and there were no combined effects for GST genotypes and the catechol O-methyltransferase genotype. We conclude that GSTM1, GSTT1, and GSTP1 genotypes do not play a strong role in susceptibility to breast cancer. However, the role of GST genotypes in age at onset and risk of breast cancer among women with a family history merits further investigation.

Adult↗
PubMed2000

Dichlorodiphenyldichloroethene, polychlorinated biphenyls, and breast cancer among African-American and white women in North Carolina.

We examined plasma dichlorodiphenyldichloroethene (DDE) and total polychlorinated biphenyl (PCB) levels in relation to breast cancer in a population-based, case-control study of African-American women (292 cases and 270 controls) and white women (456 cases and 389 controls) in North Carolina. Adjusted odds ratios (ORs) for breast cancer comparing the highest to lowest third of DDE were 1.41 [95% confidence interval (CI), 0.87-2.29] in African-American women and 0.98 (95% CI, 0.67-1.43) in white women. ORs comparing the highest to lowest third of total PCBs were 1.74 (95% CI, 1.00-3.01) in African-American women and 1.03 (95% CI, 0.68-1.56) in white women. Among African-Americans, the OR for total PCBs was highest for obese women (body mass index 234.2; OR, 4.92; 95% CI, 1.63-14.83). In contrast, the OR for DDE was highest for the leanest African-American women (body mass index, <25; OR, 3.84; 95% CI, 0.98-15.08). ORs for DDE were not elevated among women who lived or worked on farms or elevated among farming women who reported exposure to pesticides. Our results suggest absence of a strong effect for DDE or total PCBs in breast cancer but lend support for associations among subgroups of women. In our study, factors such as income, parity, breastfeeding, race/ethnicity, and body mass index influenced the relationship of organochlorines and breast cancer. Differing distributions of such factors may explain some of the inconsistencies across previous studies.

Adult↗
PubMed1999

Placental abruption and adverse perinatal outcomes.

CONTEXT: Pregnancies complicated by abruption result in increased frequency of perinatal death and decreased fetal size and gestational duration, yet the extent of placental separation and its effect on these adverse outcomes is unknown. OBJECTIVE: To assess the contribution of placental abruption and extent of placental separation to stillbirth, preterm delivery, and fetal growth restriction. DESIGN: Hospital-based, retrospective cohort study. SETTING: Mount Sinai Hospital, New York City, NY. PARTICIPANTS: A total of 53,371 pregnancies occurring in 40,789 women who were delivered of singleton births between 1986 and 1996. MAIN OUTCOME MEASURES: Risks and relative risks for stillbirth (>20 weeks), preterm delivery (<37 weeks), and fetal growth restriction (birth weight below 10th percentile for gestational age) in relation to abruption. RESULTS: The incidence of abruption was 1 % (n = 530). Abruption was associated with an 8.9-fold (95% confidence interval [CI], 6.0-13.0) adjusted relative risk (aRR) of stillbirth. Preterm birth proportions among women with and without abruption were 39.6% and 9.1 %, respectively, yielding an aRR of 3.9 (95% CI, 3.5-4.4). In the abruption group, 14.3% of neonates were growth restricted, compared with 8.1 % among all other births (aRR, 2.0; 95% CI, 1.5-2.4). Extent of placental separation had a profound effect on stillbirth (aRR for 75% separation, 31.5; 95% CI, 17.0-58.4), although evident only among those with at least 50% separation. However, the risk of preterm delivery was substantially increased even for mild abruptions (aRR for 25% separation, 5.5; 95% CI, 4.2-7.3). CONCLUSIONS: In this cohort, placental abruption had a profound impact on stillbirth, preterm delivery, and fetal growth restriction. The risk of stillbirth was dramatically increased for severe placental separation, but preterm delivery was common even among women with lesser degrees of placental separation.

Abruptio Placentae↗
PubMed1999

Chemical hair treatments and adverse pregnancy outcome among Black women in central North Carolina.

Several studies suggest that toxic chemicals in hair products may be absorbed through the scalp in sufficient amounts to increase the risks of adverse health effects in women or their infants. This case-control study of 525 Black women from three counties in North Carolina who had delivered a singleton, liveborn infant examined whether exposure to chemicals used in hair straightening and curling increased the odds that the infant was preterm or low birth weight. Cases consisted of 188 preterm and 156 low birth weight births (for 123 women, their infant was both low birth weight and preterm). Controls were 304 women who delivered term and normal birth weight infants. Women who used a chemical hair straightener at any time during pregnancy or within 3 months prior to conception had an adjusted odds ratios (OR) of 0.7 (95% confidence interval (CI) 0.4-1.1) for preterm birth and 0.6 (95% CI 0.4-1.1) for low birth weight. Exposure to chemical curl products was also not associated with preterm delivery (adjusted OR = 0.9, 95% CI 0.5-1.8) or low birth weight (adjusted OR = 1.0, 95% CI 0.5-1.9). Despite this failure to find an association, continued search for risk factors to which Black women are uniquely exposed is warranted.

Abnormalities, Drug-Induced↗
PubMed1999

Bacterial vaginosis associated with HIV infection in pregnant women from North Carolina.

BACKGROUND: We investigated whether bacterial vaginosis is associated with HIV infection in pregnant women in North Carolina, U.S.A. METHODS: At 24 to 29 weeks' gestation, we recruited 724 women receiving prenatal care to provide interview information and vaginal swabs for Gram's stain scoring of vaginal flora. FINDINGS: As vaginal flora score increased, prevalence of HIV increased (trend p = .03). HIV prevalence was 0.8% (4 of 489 patients), 1.2% (1 of 84 patients), and 3.3% (5 of 151 patients) among women with normal, intermediate, and abnormal vaginal flora, respectively. All HIV-infected women were free from AIDS and were taking antiretroviral medication. Compared with women with normal vaginal flora, the relative risk for prevalence of HIV infection with intermediate flora was 1.5 (95% confidence interval [CI], 0.2, 12.9) and with abnormal flora was 4.0 (95% CI, 1.1, 14.9). The association between abnormal vaginal flora and HIV infection could not be explained by age, ethnicity, number of sexual partners in the past 6 months, sexually transmitted diseases (STDs), or douching during pregnancy. INTERPRETATION: In a population with a relatively low HIV prevalence, vaginal flora abnormalities were associated with prevalent HIV infection. We cannot determine whether vaginal flora abnormalities increase women's susceptibility to HIV infection or become more common after infection. The increased prevalence of bacterial vaginosis among HIV-infected pregnant women increases risk for preterm delivery. Incidence studies are required to discern whether control of bacterial vaginosis might reduce HIV infectivity.

AIDS-Related Opportunistic Infections↗
PubMed1999

Magnetic field exposure and cardiovascular disease mortality among electric utility workers.

Laboratory studies suggest that electric and magnetic field exposure may affect heart rate and heart rate variability. Epidemiologic evidence indicates that depressed heart rate variability is associated with reduced survival from coronary heart disease as well as increased risk of developing coronary heart disease. The authors examined mortality from cardiovascular disease in relation to occupational magnetic field exposure among a cohort of 138,903 male electric utility workers from five US companies over the period 1950-1988. Cardiovascular disease deaths were categorized as arrhythmia related (n = 212), acute myocardial infarction (n = 4,238), atherosclerosis (n = 142), or chronic coronary heart disease (n = 2,210). Exposure was classified by duration of work in jobs with elevated magnetic field exposure and indices of cumulative magnetic field exposure. Adjusting for age, year, race, social class, and active work status, longer duration in jobs with elevated magnetic field exposure was associated with increased risk of death from arrhythmia-related conditions and acute myocardial infarction. Indices of magnetic field exposure were consistently related to mortality from arrhythmia and acute myocardial infarction, with mortality rate ratios of 1.5-3.3 in the uppermost categories. No gradients in risk were found for atherosclerosis or for chronic coronary heart disease. These data suggest a possible association between occupational magnetic fields and arrhythmia-related heart disease.

Cardiovascular Diseases↗
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

Sperm aneuploidy among Chinese pesticide factory workers: scoring by the FISH method.

BACKGROUND: A study of the prevalence of sperm aneuploidy among pesticide factory workers was conducted in Anhui, China. METHODS: We recruited 75 men: 32 subjects from a large pesticide-manufacturing plant and 43 subjects from a nearby textile factory free of pesticide exposure. Each subject met the following criteria: age of 20-40 years; continuous work in the plant for 3 months prior to the study, no congenital anomalies or acquired disease of the external genitalia and no history of recent febrile illness or mumps. Within one hour after collection from each subject, semen was evaluated in terms of several parameters and smear slides were prepared. RESULTS: Exposure assessment revealed that workers in the pesticide plant were exposed to ethyl parathion or methamidophos, each of which is a potent organophosphate pesticide, at a median level of 0.02 mg/m3 (8-hour time weighted average as measured by personal pump) while workers in the control plant had no such occupational exposure. Twenty-nine semen slides (13 from the exposed group and 16 from the unexposed group) were randomly chosen for aneuploidy scoring by the three-color fluorescence in situ hybridization (FISH) method with scorers being unaware of exposure status. Median semen parameters were as follows for exposed (and unexposed) men: abstinence period, 3 days (4 days); sperm concentration, 52.8x10(6)/ml (53.1x10(6)/ml); proportion of sperm with normal motility, 50.5% (61.3%); and proportion of sperm with normal morphology, 59% (61.5%). The specific chromosome abnormalities of interest were disomy for chromosome 18 and the three different types of sex chromosome disomy (i.e. XX, XY, YY disomy). The crude proportion of all aneuploidy combined was 0.30% and 0.19% for sperm from exposed and unexposed men, respectively. Poisson regression with overdispersion adjustment yielded significantly different crude risks of aneuploidy - 3.03 and 1.94 per 1,000 sperm from exposed and unexposed men, respectively - giving a rate ratio of 1.56 (95% CI, 1.06-2.31). The regression coefficients remained statistically significant after adjustment for inter-technician variability giving a rate ratio of 1.51 (95% CI, 1. 04-2.20). CONCLUSIONS: We conclude that occupational exposure to organophosphate pesticides moderately increases the prevalence of sperm aneuploidy.

Adult↗
PubMed1999

Paraoxonase polymorphism and its effect on male reproductive outcomes among Chinese pesticide factory workers.

BACKGROUND: Serum paraoxonase has been associated with the metabolism of organophosphate pesticides in humans. Molecular analysis of the human paraoxonase gene (PON1) has revealed that Arg192 homozygotes have a greater detoxifying capability than Gln192 homozygotes. We examined the effects of PON1 genotypes on male reproductive outcomes and its interaction with exposure to organophosphate pesticides. METHODS: We studied 60 Chinese pesticide-factory workers and 89 textile-factory workers who were unexposed to pesticides. The respective allele frequencies of Arg192 and Gln192 were 0.62 and 0.38. Pesticide exposure among 36 exposed subjects and 12 unexposed subjects, regardless of gender, was assessed by personal measurement of pesticide residues over an entire 8-hr shift and measurement of urinary p-nitrophenol level over a 24-hr period. We analyzed semen and hormone data collected from male subjects. RESULTS: When the three PON1 genotypes were analyzed separately, a gene dose effect was not detected. We used the unexposed Arg192 homo/heterozygotes as the reference group, and re-analyzed the data. Exposed Arg192 homo/heterozygotes had significantly lower sperm count (chi 2 = 9.01, P < 0.01) and lower percentage of sperm with normal morphology (chi 2 = 4.18, P < 0.05) than the reference group. Both unexposed Gln192 homozygotes (chi 2 = 4.90, P < 0.05) and exposed Arg192 homo/heterozygotes (chi 2 = 10.00, P < 0.01) showed significantly lower sperm concentrations than the reference group. In addition, exposed Arg192 homo/heterozygotes had significantly higher serum LH levels (chi 2 = 7.94, P < 0.01) than the reference group. CONCLUSIONS: Because of a small sample size, our findings are highly preliminary. Nevertheless, it calls for further investigation of the interaction between the PON1 genotype and organophosphate pesticide exposure on male reproductive outcomes.

Adult↗
PubMed1999

Accuracy of industry and occupation on death certificates of electric utility workers: implications for epidemiologic studies of magnetic fields and cancer.

A substantial epidemiologic literature has relied on occupation and industry information from death certificates to make inferences about the association of electric and magnetic field exposure with cancer, but the validity of the occupational data on death certificates is questionable. We compared occupation and industry information from death certificates to company work histories for 793 electric utility workers who died from brain cancer (n=143), leukemia (n=156), lung cancer (n=246, randomly sampled), and non-cancer causes (n=248, randomly sampled). Nearly 75% of death certificates correctly indicated utility industry employment and of those, 48% matched the longest held occupation derived from company work histories. Hence, only 36% matched on both industry and occupation. We computed odds ratios relating occupations involving magnetic field exposure to brain cancer and leukemia both for the occupation listed on the death certificate and for the longest-held occupation based on company records in order to examine the impact of exposure misclassification based on reliance on the death certificate information. For brain cancer, the odds ratio was 1.2 based on death certificates and 1.7 based on company work history, suggesting some attenuation due to misclassification. For leukemia, death certificate information yielded an odds ratio of 0.9, whereas company work histories yielded an odds ratio of 1.3. Although work histories are limited to the period of employment in a specific company, these data suggest that there is substantial misclassification in use of death certificate information on industry and occupation of utility workers, as found in other industries. The limited quality of occupation and industry information on death certificates argues against relying on such information to evaluate modest associations with mortality.

Adult↗
PubMed1999

Association between bacterial vaginosis and fetal fibronectin at 24-29 weeks' gestation.

OBJECTIVE: To investigate the relationship between fetal fibronectin and bacterial vaginosis, which are associated with an increased risk for preterm delivery. METHODS: Researchers for the Pregnancy, Infection and Nutrition Study, a cohort study of pregnant women at three central North Carolina sites, collected genital tract specimens from all enrolled women between 24 and 29 weeks' gestation. Among women with last menstrual periods between March 10, 1995, and August 15, 1996, 868 pregnancies were eligible for this analysis. Fetal fibronectin was assessed by a dipstick immunoassay kit. Bacterial vaginosis was evaluated by Nugent-scored, Gram-stained vaginal smears (scores of 7-10 considered positive). RESULTS: Overall, 6.3% of women had positive fetal fibronectin test results, and 18.8% had bacterial vaginosis. The unadjusted relative risk (RR) of fetal fibronectin-positivity comparing women with bacterial vaginosis to those without bacterial vaginosis was 1.6 (95% confidence interval [CI] 1.1, 2.5). Using multiple logistic regression to adjust for race, maternal age, parity, and location of care, women who had bacterial vaginosis and smoked at the time of recruitment were at substantially increased risk of fetal fibronectin-positivity (RR 7.8, 95% CI 2.2, 27.8) compared with smokers without bacterial vaginosis. Among nonsmokers, bacterial vaginosis was not associated with fetal fibronectin-positivity (RR 1.0, 95% CI 0.4, 2.4). These results were essentially unchanged after adding the requirement of vaginal pH exceeding 4.5 to the bacterial vaginosis definition. CONCLUSION: Fetal fibronectin was associated positively with bacterial vaginosis, but only among women who smoked. These results might provide clues as to the biologic relationship between smoking, infection, and preterm delivery.

Adolescent↗
PubMed1999

Cervical dimensions and risk of preterm birth: a prospective cohort study.

OBJECTIVE: To examine the relation between cervical dilatation and length and the risk of spontaneous preterm birth, including its subtypes preterm labor and preterm premature rupture of membranes (PROM). METHODS: Cervical dimensions assessed by clinical examination were recorded prospectively at 24-29 weeks' gestation in 871 subjects with singleton pregnancies who were followed to delivery. Relative risks (RRs) of preterm birth, preterm labor, and preterm PROM were calculated for clinically distinguishable categories of cervical dilatation and length and for cervical score (length minus dilatation). Regression analysis was used to adjust for confounding. Time to delivery from baseline examination was summarized using survival analysis. RESULTS: There were 73 spontaneous preterm births (8.3%), 46 preterm labors and 27 cases of preterm PROM. All cervical measurements were associated with increased risks of preterm birth, with increasing abnormality more strongly predictive of risk. The adjusted RR for preterm birth with dilatation of at least 0.5 cm was 2.9 (95% confidence interval [CI] 1.2, 7.3); for length of 1.5 cm or less, the RR was 2.1 (95% CI 1.0, 4.5), and for cervical score less than 2.0, the RR was 2.8 (95% CI 1.4, 5.6). The association with cervical measurements was stronger for preterm PROM than for preterm labor, although precision was limited. These measurements had high specificity (93-99%) and low sensitivity (8-20%) for predicting preterm birth. CONCLUSION: In asymptomatic women at 24-29 weeks' gestation, greater cervical dilatation and shorter length were associated with increased risk of spontaneous preterm delivery, particularly preterm PROM.

Adult↗
PubMed1999

Determinants of participation in an epidemiological study of preterm delivery.

We describe the study design and patterns of participation for a cohort study of preterm delivery, focused on genital tract infections, nutrition, tobacco use, illicit drugs and psychosocial stress. Women are recruited at 24-29 weeks' gestation from prenatal clinics at a teaching hospital and a county health department. We recruited 57% of the first 1843 eligible women; 29% refused and 8% could not be contacted. White women were somewhat more likely to participate than African-American women (61% vs. 54% respectively). More notable differences were found comparing teaching hospital and health department clinics (71% vs. 47% participation respectively), with the health department clinic having a greater proportion refuse (24% vs. 33%) and more women who could not be contacted (4% vs. 11%). Participation was affected only minimally by day or timing of recruitment, but inability to contact diminished substantially as the study continued (13-0%). Refusals were largely unrelated to patient attributes. Lower education predicted inability to contact. Risk of preterm delivery was 14% among recruited women, 10% among women who refused, and 15% among women whom we were not able to contact, demonstrating that, overall, risk status was not lower among recruited women.

Adolescent↗
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

Race/ethnicity, vaginal flora patterns, and pH during pregnancy.

OBJECTIVES: To investigate the relationship between bacterial vaginosis during pregnancy and black race/ethnicity. STUDY DESIGN: Gram staining was used to evaluate vaginal flora in 842 women at 24 to 29 weeks' gestation. RESULTS: Overall, 22.3% of blacks and 8.5% of whites had bacterial vaginosis. Vaginal pH and flora differed significantly by race/ethnicity; blacks were more likely to have pH > or = 4.5, no lactobacilli, small gram-variable and -negative rods, and Mobiluncus compared with whites (odds ratios 1.6, 1.5, 1.4, and 10.6, respectively). Quantity of morphotypes also differed, especially for Mobiluncus. Among women with Mobiluncus present (12.0% of blacks and 1.3% of whites), 73.3% of blacks compared with 40.0% of whites had the highest level. Adjustment for sociodemographics, sexual activity, sexually transmitted diseases, health behavior, and sexual hygiene did not explain these differences. CONCLUSION: We observed race/ethnicity differences in vaginal flora ecology. These differences may ultimately play a role in the larger proportion of preterm deliveries among black women compared with white women.

Adolescent↗
PubMed1999

Comparative analyses of the studies of magnetic fields and cancer in electric utility workers: studies from France, Canada, and the United States.

OBJECTIVES: To summarise and to facilitate comparison of three major studies of electric utility workers that examined the relation between quantitative measurements of occupational exposure to magnetic fields and risk of brain cancer and leukaemia. These studies have been interpreted as providing conflicting evidence. METHODS: A common analytical approach was applied to data from the five cohorts included in the three studies based on original data from four of the cohorts, and published data from one additional cohort. A nested case-control design with conditional logistic regression was used to estimate the relative risk/10 microtesla-years (microT-years) for each of the contributing cohorts and for the combined data. The homogeneity of these estimates among the studies was also evaluated. RESULTS: Apparent inconsistencies in the findings of these studies can be explained by statistical variation. Overall, the studies suggest a small increase in risk of both brain cancer and leukaemia. Different methodological choices had little impact on the results. Based on a combined analysis of data from all five studies, the relative risk/10 microT-years was 1.12 (95% confidence interval (95% CI) 0.98 to 1.28) for brain cancer, and 1.09 (95% CI 0.98 to 1.21) for leukaemia. CONCLUSIONS: The combined estimates seem to provide the best summary measures of the data from all studies. However, fluctuations in risks among studies may reflect real differences, and the exposure measurements in different studies may not be entirely comparable.

Brain Neoplasms↗