Risk factors for mental disorder hospitalization after the Persian Gulf War: U.S. Armed Forces, June 1, 1991-September 30, 1993.

Effects of Persian Gulf War (August 2, 1990-July 31, 1991) and Gulf War occupation on post-War hospitalization risk were evaluated through Cox proportional hazards modeling. Active-duty men (n = 1,775,236) and women (n = 209,760) in the Army, Air Force, Navy, and Marine Corps had 30,539 initial postwar hospitalizations for mental disorders between June 1, 1991 and September 30, 1993. Principal diagnoses in the Defense Manpower Data Center hospitalization database were grouped into 10 categories of ICD-9-CM codes. Gulf War service was associated with significantly greater risk for acute reactions to stress and lower risk for personality disorders and adjustment reactions among men. Personnel who served in ground war support occupations (men and women) were at greater risk for postwar drug-related disorders. Men who served in ground war combat occupations were at higher risk for alcohol-related disorders. Longitudinal studies of health, hospitalization, and exposure beginning at recruitment, are needed to better understand how exposure to combat affects the mental health of military personnel.

Effects of maternal work activity during pregnancy on infant malformations.

This article examines the association between two birth defects, neural tube defects and oral cleft defects, and maternal physical work demands during the periconceptional period. A case-control study was conducted by comparing exposure characteristics of mothers of malformed infants, as ascertained from the New York State Congenital Malformations Registry (n = 520), with mothers of non-malformed infants (n = 1154). Case groups were further subdivided on whether infants had additional defects. Occupational exposure information was collected from a self-administered questionnaire, and demographic variables from vital records. The results showed no general differences between cases and controls in most variables. However, those infants with cleft defects plus additional defects tended to have a marginally increased risk (odds ratio = 1.76; 95% confidence interval, 1.02-3.21) in relation to maternal jobs requiring standing (> or = 75% of time). We suggest that exposure assessment be improved and defects subdivided for future studies.

Maternal caffeine consumption and spontaneous abortion: a prospective cohort study.

We investigated the relation between caffeine beverage consumption and spontaneous abortion in 2,967 pregnant women planning to deliver at Yale-New Haven Hospital in 1988-1992. We evaluated coffee, tea, and soda drinking in the first month of pregnancy in interviews before the end of the sixteenth week of gestation. We obtained information on 98.2% of the pregnancies (including 2,714 singleton livebirths and 135 spontaneous abortions). As compared with abstention from caffeine beverages (coffee, tea, and soda), the adjusted odds ratios for spontaneous abortion associated with consumption of 1-150, 151-300, and > 300 mg caffeine daily were 0.81 [95% confidence interval (CI)) = 0.54-1.20], 0.89 (95% CI = 0.48-1.64), and 1.75 (95% CI = 0.88-3.47), respectively. Drinking > or = 3 cups of tea or coffee was associated with elevated risks of spontaneous abortion (adjusted odds ratio = 2.33, 95% CI = 0.92-5.85; and adjusted odds ratio = 2.63, 95% CI = 1.29-5.34, respectively). These results, if replicated, suggest that some ingredient (or correlate) of tea or coffee may account for some of the observed association of caffeine with spontaneous abortion. In this study, caffeine consumption is more strongly related to spontaneous abortion than alcohol or cigarette use in early pregnancy.

Exposure to electromagnetic fields during pregnancy with emphasis on electrically heated beds: association with birthweight and intrauterine growth retardation.

Several animal and human studies indicate that fetal growth may be retarded following exposure to electromagnetic fields (EMF). We conducted a prospective study (N = 2,967) to evaluate the relation of birthweight and fetal growth retardation with use of electrically heated beds (electric blankets and heated water beds) during pregnancy. A "nested" study design allowed monitoring of exposure at different stages of pregnancy using both direct and indirect methods. We assessed EMF exposure using personal monitors, home measurement, video display terminal use, and wire code. Exposure to EMF during pregnancy, either at conception, at < or = 16 weeks, or in the third trimester, showed no important relation to risk of low birth-weight or fetal growth retardation. This result was the same whether we used subjective measures of exposure or direct measurement. Use of video display terminals at home or work, exposure to > or = 2.0-milligauss fields as measured by home or personal monitors, and home wire code were unrelated to the reproductive outcomes studied. A time-weighted analysis of electric bed use, which accounted for strength of EMF exposure and hours of use, also showed evidence of no meaningful increase in risk. None of the exposure measures showed a dose response relation to risk. We conclude that risk of low birth-weight and intrauterine growth retardation is not increased after electrically heated bed use during pregnancy.

Human exposure to magnetic fields: a comparative assessment of two dosimeters.

Two types of dosimeters for measuring human exposure to 60 Hz magnetic fields were compared. Fifty adults wore the single-axis, wrist model AMEX (average magnetic field exposure system) and the triple axis, hip-pocket or pouch model AMEX-3D meters for 2 days. Ninety-six percent of the tests were accomplished without apparent dosimeter failure. The average root mean square magnetic flux density measurements with the AMEX-3D (mean = 0.10 microT, S.D. = 0.07, range = 0.03-0.31) were significantly higher than with the AMEX meter (mean = 0.07 microT, S.D. 0.05, range = 0.02-0.27 microT) (t test, P < 0.01). There was substantial correlation between the AMEX and the AMEX-3D measurements (Pearson's correlation coefficient = 0.65, P < 0.01) but poor concordance (Intraclass correlation coefficient = -0.25). These results suggest that there is a wide variation in exposure to extremely low frequency magnetic fields in the population. Magnetic field measurements with the AMEX-3D are nearly always higher than with the AMEX dosimeters. Caution is advised when comparing magnetic field measurements made with different types of dosimeters.

Comparison of mother's occupation and industry from the birth certificate and a self-administered questionnaire.

Maternal occupations recorded on birth certificates are a potential data source for evaluation of reproductive hazards, but may not accurately identify jobs held during the sensitive first trimester. Mothers' occupation and industry during 1 month before and 3 months after conception were reported on 1,760 mailed questionnaires. These were compared to mothers' most recent occupation and industry recorded on birth certificates. Overall, 72% of occupations and 77% of industries reported on the birth certificate agreed with that recorded on the questionnaire. Agreement was similar for mothers of normal and malformed infants. Among those that did not agree, 344 (75%) disagreed on the mother's employment status during the periconceptional period, rather than the actual occupation. For surveillance and hypothesis-generation using birth certificate data, it is important to obtain a correct description of whether the mother held a job outside the home during sensitive periods of her pregnancy.

Congenital defects and electric bed heating in New York State: a register-based case-control study.

Exposure to 60-cycle electromagnetic fields has been hypothesized to be a cause of childhood cancer and congenital defects. Because electric bed heaters are a major source of variation in electromagnetic field exposure in the population, the authors conducted a case-control study in 1988-1989 to examine the relations between congenital defects and the use of electric blankets and heated waterbeds. Cases were identified by the New York State Congenital Malformations Registry as babies with cleft palate (n = 121), cleft lip with or without cleft palate (n = 197), born in 1983-1984, and anencephalus and spina bifida (n = 224), born in 1983-1986, all to upstate New York residents. Controls were selected at random from birth registrations individually matched to cases by maternal race, age, home county, month of last menses, and child's sex. Information on periconceptional electric blanket and heated waterbed use as well as known and suspected risk factors for defects was obtained from questionnaires mailed to the mothers. Matched odds ratio estimates and 95% confidence intervals (CIs) for electric blanket use relative to nonuse were 0.8 (95% CI 0.3-2.1) for cleft palate, 0.7 (95% CI 0.3-1.3) for cleft lip, and 0.9 (95% CI 0.5-1.6) for neural tube defects. The respective odds ratios for heated waterbed use were nearly identical to these. Adjustment for potential confounding factors (maternal education, vitamin use, smoking) and stratification by season of conception and bed heat control setting had no meaningful effect on odds ratios. These results suggest that 60-cycle fields do not cause neural tube and oral cleft defects.

Ambient 60-Hz magnetic flux density in an urban neighborhood.

A residential neighborhood in Buffalo, NY, was surveyed with a magnetic field meter to evaluate whether or not spot measurements are reliable predictors of the 60-Hz fields at street corners and residences. The results of repeated measurements over 7 days at 33 street corners in this neighborhood indicate that day-to-day variation in power line magnetic fields is negligible (intraclass correlation coefficient = 0.94). Multivariate linear regression analysis of the data indicates that transmission lines and thick, three-phase primary wires near the field measurement site are strong predictors and account for the majority of the ambient magnetic field variance between locations (multiple correlation coefficient squared = 0.60; F ratio = 22.2, P less than .001). Magnetic fields measured at the front sidewalk were highly correlated with fields at the front doorsteps of 45 homes in this neighborhood (gamma = 0.81). These results suggest that ambient power line magnetic field levels at urban residences can be reliably characterized on a one-time site inspection using a hand-held magnetic field meter and a simple wiring classification system.

Relationships between laterality of congenital upper limb reduction defects and school performance.

Eighty children (34 males, 46 females) with congenital upper limb reduction defects who attended a regional amputee clinic between 1956 and 1986 were classified as to whether they exhibited learning difficulties in school, as indicated by grade failure or by placement in learning disability classrooms. Children with right-sided defects were more likely to encounter learning difficulties than were children with left-sided defects (Chi-square = 6.8; df = 1; p less than 0.01). Children with right-limb defects also were more likely than children with left-limb defects to experience reading problems (Chi-square = 5.9; df = 1; p less than 0.05). These results suggest the need for neuropsychological and neurophysiological study of children with limb reduction defects.