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Biomedical subjects

D A Savitz

Publications and source records attributed to D A Savitz.

At least 37 records · Page 2Linked to original sources
PubMed2001

Role of structural birth defects in preterm delivery.

The proportion of preterm births associated with structural birth defects has not been adequately quantified. We explored the proportion of preterm infants with structural birth defects diagnosed in the first year of life, as well as the specific phenotypes of birth defects occurring among preterm infants. The data used were from the California Birth Defects Monitoring Program, a population-based registry, as well as data from California vital records corresponding to births and fetal deaths in the period 1984-96. The prevalence of structural birth defects exceeded 8% among deliveries with gestational ages < or = 30 weeks, and prevalence decreased to 2% as gestational age increased to > or = 37 weeks gestation. The decreasing prevalence pattern with increasing gestational age was observed for a variety of anatomically defined birth defect groups suggesting that certain birth defects were not the sole contributors to the elevated prevalences among preterm births. Decreasing prevalence with increasing gestational age was also observed across strata of maternal race/ethnicities, ages, infant's sex and each year studied. These data indicate that structural birth defects may contribute significantly to the proportion of infants who are delivered before 37 weeks gestation.

Congenital Abnormalities↗
PubMed2001

Tocolytic therapy for preterm labour: assessing its potential for reducing preterm delivery.

Preterm labour (PTL) is a major contributor to preterm delivery (PTD) but delivery is often not preventable by current therapies. We conducted this study to determine the proportion of women with PTL who were and who were not candidates for tocolytic therapy. The cohort comprised residents of Olmsted County, Minnesota who delivered at >20 weeks' gestation in 1985--94 and who experienced PTL. Medical records were abstracted to identify episodes of PTL, its treatment and outcome. We developed an algorithm that accounted for gestation at delivery and pregnancy complications to determine the proportion of pregnancies complicated by PTL that were candidates for tocolytic therapy. Of 651 pregnancies complicated by PTL, a 50% probability sample, stratified by delivery year, were selected and abstracted. The cumulative incidence of PTL ranged from 3.6 to 6.4 per 100 deliveries of live or stillborn infants. Tocolysis was not contraindicated for 49.4% of all women with PTL and for a third of women with only one PTL episode. Delivery was delayed to >35 weeks in 53.8% of candidates for tocolysis. Only an additional 11.7% of women with one or more PTL episodes could have had their PTD delayed beyond 35 weeks if a perfect tocolytic therapy had been available. Many pregnancies complicated by PTL occurred at > or =35 weeks or involved maternal or obstetric factors that contraindicated tocolytic medications. The maximum incremental benefit that could be expected of a new safe and efficacious tocolytic therapy would be to reduce current PTD rates resulting from PTL by about 12%.

Adolescent↗
PubMed2001

Residential pesticide exposure and neuroblastoma.

Neuroblastoma is the most common neoplasm in children under 1 year of age. We examined the relation between residential exposure to pesticides and neuroblastoma, using data from a case-control study of risk factors for neuroblastoma. Incident cases of neuroblastoma (N = 538) were identified through the Pediatric Oncology Group and the Children's Cancer Group. One age-matched control was identified for each case by random digit dialing. Telephone interviews with each parent collected information on residential exposure to pesticides. Pesticide use in both the home and garden were modestly associated with neuroblastoma [odds ratio (OR) = 1.6 (95% confidence interval [95% CI] = 1.0-2.3, and OR = 1.7 (95% CI = 0.9-2.1), respectively]. Compared with infants [OR = 1.0 (95% CI = 0.6-2.0)], stronger associations were found for garden pesticides in children diagnosed after 1 year of age [OR = 2.2 (95% CI = 1.3-3.6)], which suggests that pesticides may act through a mechanism more common for neuroblastomas in older children. There was no evidence of differential pesticide effects in subgroups of neuroblastoma defined by MYCN oncogene amplification or tumor stage.

Canada↗
PubMed2001

Parental occupational exposures to electromagnetic fields and radiation and the incidence of neuroblastoma in offspring.

We examined parental occupational exposures to electromagnetic fields and radiation and the incidence of neuroblastoma in offspring. Cases were 538 children diagnosed with neuroblastoma between 1992 and 1994 in the United States or Canada. Age-matched controls were selected by random-digit dialing. Occupational exposures to electrical equipment and radiation sources were classified by an industrial hygienist, and average exposures to extremely low frequency magnetic fields were estimated using a job exposure matrix. Maternal exposure to a broad grouping of sources that produce radiofrequency radiation was associated with an increased incidence of neuroblastoma (odds ratio = 2.8; 95% confidence interval = 0.9-8.7). Paternal exposure to battery-powered forklifts was positively associated with neuroblastoma (odds ratio = 1.6; 95% confidence interval = 0.8-3.2), as were some types of equipment that emit radiofrequency radiation (odds ratios congruent with 2.0); however, the broad groupings of sources that produce ELF fields, radiofrequency radiation, or ionizing radiation were not associated with neuroblastoma. Paternal average extremely low frequency magnetic field exposure >0.4 microTesla was weakly associated with neuroblastoma (odds ratio = 1.6; 95% confidence interval = 0.9-2.8), whereas maternal exposure was not. Overall, there was scant supportive evidence of strong associations between parental exposures in electromagnetic spectrum and neuroblastoma in offspring.

Case-Control Studies↗
PubMed2001

Smoking and pregnancy outcome among African-American and white women in central North Carolina.

Despite extensive research on tobacco smoking during pregnancy, few studies address risks among African-American and white women, groups that differ in brand preference and smoking habits. The Pregnancy, Infection, and Nutrition Study is a prospective cohort study that included 2,418 women with detailed information on smoking during pregnancy, including brand, number of cigarettes per day, and changes during pregnancy. We analyzed risk of preterm birth (<37 and <34 weeks' gestation) and small-for-gestational-age deliveries in relation to tobacco use. Pregnant African-American smokers differed markedly from whites in brand preference (95% vs 26% smoked menthol cigarettes) and number of cigarettes per day (1% of African-Americans and 12% of whites smoked 20+ cigarettes per day). Smoking was not related to risk of preterm birth overall, but cotinine measured at the time of delivery was (adjusted odds ratio = 2.2, 95% confidence interval = 1.1-4.5). A clear association and dose-response gradient was present for risk of fetal growth restriction (risk ratio for 20+ cigarettes/day = 2.4, 95% confidence interval = 1.4-4.0). Associations of tobacco use with preterm premature rupture of amniotic membrane resulting in preterm birth were notably stronger than the associations with other types of preterm birth.

Black or African American↗
PubMed2001

Occupational sunlight exposure and mortality from non-Hodgkin lymphoma among electric utility workers.

This case-control study examined occupational sunlight exposure and death from non-Hodgkin lymphoma (NHL) and NHL subtypes among 188 cases and 1880 controls selected from a cohort of 138,905 male electric utility workers. Exposure was classified according to work history linked to indices of cumulative sunlight exposure. Odds ratios and 95% confidence intervals were derived from conditional logistic regression models and were conditioned on the matching factors birth year and ethnicity. Mortality from NHL and intermediate/high-grade lymphomas was not related to cumulative sunlight exposure, with odds ratios around the null. For low-grade lymphomas, a dose-response gradient was observed for exposure in the past 12 to 21 years, but this result seemed to be sensitive to cut points for categorization of cumulative exposure. These data do not provide evidence for an association between occupational sunlight exposure and mortality from NHL or NHL subtypes.

Adult↗
PubMed2000

Occupation and adult gliomas.

Lifetime job histories from a population-based, case-control study of gliomas diagnosed among adults in the San Francisco Bay area between August 1991 and April 1994 were evaluated to assess occupational risk factors. Occupational data for 476 cases and 462 controls were analyzed, with adjustment for age, gender, education, and race. Imprecise increased risks were observed for physicians and surgeons (odds ratio (OR) = 3.5, 95% confidence interval (CI): 0.7, 17.6), artists (OR = 1.9, 95% CI: 0.5, 6.5), foundry and smelter workers (OR = 2.6, 95% CI: 0.5, 13.1), petroleum and gas workers (OR = 4.9, 95% CI: 0.6, 42.2), and painters (OR = 1.6, 95% CI: 0.5, 4.9). Legal and social service workers, shippers, janitors, motor vehicle operators, and aircraft operators had increased odds ratios only with longer duration of employment. Physicians and surgeons, foundry and smelter workers, petroleum and gas workers, and painters showed increased risk for both astrocytic and nonastrocytic tumors. Artists and firemen had increased risk for astrocytic tumors only, while messengers, textile workers, aircraft operators, and vehicle manufacturing workers showed increased risk only for nonastrocytic tumors. Despite study limitations, including small numbers for many of the occupational groups, a high percentage of proxy respondents among cases, and lack of specific exposure information, associations were observed for several occupations previously reported to be at higher risk for brain tumors generally and gliomas specifically.

Adult↗
PubMed2000

Concordance among measures of pregnancy outcome based on fetal size and duration of gestation.

Epidemiologic and clinical studies of pregnancy outcome often consider a variety of related, overlapping outcome measures. The overlap among these measures was analyzed using data from the Mount Sinai Hospital Perinatal Data Base, New York City, New York. A total of 52,621 births from 1986 through 1996 were included, with information on gender, ethnicity, birth weight, and gestational age assigned based on last menstrual period or early ultrasound. The authors considered very low birth weight (VLBW) (<1,500 g), low birth weight (LBW) (<2,500 g), degrees of preterm delivery (less than 32, 34, and 37 weeks' gestation), and small for gestational age (less than the 10th percentile of weight for gestational age) births. Infants at the extremes of gestational age (<32 or 34 weeks' gestation) were almost always LBW (97.6 and 91.7%, respectively), and those who were VLBW were almost always preterm (99.2%). However, only 69.2% of LBW infants were preterm, and 50.2% of preterm infants were LBW (kappa = 0.54). Only for VLBW and less than 32 weeks' gestation were both measures of overlap at least 70% (kappa = 0.98). The lack of concordance among measures suggests that multiple outcome measures be considered and that results from analyses using disparate measures not be compared directly.

Adult↗
PubMed2000

Occupational sunlight exposure in relation to suicide among electric utility workers.

BACKGROUND: Occupational sunlight exposure was examined in relation to death from suicide in a United States cohort of 138,905 male electric utility workers. METHODS: Case-control sampling included 536 deaths from suicide and 5,348 eligible controls randomly selected from the cohort. Exposure was classified based on work history linked to indices of cumulative sunlight exposure. RESULTS: Mortality from suicide was not associated with estimates of recent and career occupational sunlight exposure, with adjusted odds ratios around unity. Occupational sunlight exposure was positively associated with nonviolent suicides, but no dose-response gradient was observed and risk estimates were notably imprecise. CONCLUSIONS: These data provide evidence against an association between occupational sunlight exposure and mortality from suicide.

Case-Control Studies↗
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

Bacterial vaginosis and cervical dilation and effacement at 24-29 weeks' gestation.

The purpose of this study was to investigate the association between bacterial vaginosis (BV) and cervical dilation and effacement, as measures of impending preterm delivery. The Pregnancy, Infection, and Nutrition Study collected genital tract specimens and documented cervical change from 807 eligible women between 24 and 29 weeks' gestation. BV was assessed with Nugent-scored vaginal smears, and analyzed in relation to cervical measurements. At 24-29 weeks' gestation, <7% of women had a dilated cervix, 31% had a cervix < or =2 cm, and 17.3% had BV. Unadjusted analyses found no associations between BV and cervical measurements. Adjusted logistic regression suggested an association between BV and cervical effacement among women with a sexually transmitted disease (STD) earlier in pregnancy (odds ratio = 1.9, 95% CI 0.8-4.3). Stratified analyses for BV/dilation also suggested interaction with STDs. Overall, BV was not association with cervical dilation or effacement at 24-29 weeks' gestation.

Cervix Uteri↗
PubMed2000

A population-based case-control study of farming and breast cancer in North Carolina.

We examined the role of farming and pesticide exposure among 862 cases and 790 controls in a population-based, case-control study of breast cancer conducted in North Carolina between 1993 and 1996. We obtained exposure information through personal interview. Increasing duration of farming was inversely associated with breast cancer risk; odds ratios (95% confidence intervals) were 1.2 (0.8-1.7), 0.8 (0.5-1.2), 0.7 (0.5-1.1), and 0.6 (0.4-0.9) for 1-10, 11-17, 18-23, and >23 years of farming, respectively, relative to nonfarmers. Inverse associations persisted when farming was restricted to calendar time periods of 2,2-bis(p-chlorophenyl)- 1,1,1-trichloroethane (DDT) use or to farming at ages 9-16. Among women who farmed, odds ratios (ORs) were elevated for those who reported being present in fields during or shortly after pesticide application (OR = 1.8, 95% CI = 1.1-2.8) and for those who reported not using protective clothing while applying pesticides (OR = 2.0; 95% CI = 1.0-4.3), but not among those who reported using protective clothing (OR = 0.8; 95% CI = 0.4-1.8). We conclude that residence or work on farms may be associated with a reduced risk of breast cancer. Nevertheless, our results suggest a possible increased risk of breast cancer among a subgroup of farming women who were most likely to be exposed to pesticides.

Adult↗
PubMed2000

Occupational pesticide exposure and semen quality among Chinese workers.

This study investigated the association between occupational pesticide exposure and semen quality among Chinese workers. Male workers, 32 who were exposed to organophosphate pesticides and 43 who were not exposed were recruited from two nearby factories and interviewed. Following a work shift, semen and urine samples were collected for pesticide metabolite analysis. Semen samples were analyzed for sperm concentration, percentage of motility, and percentage of normal structure. Within the exposed group, the mean end-of-shift urinary p-nitrophenol levels were 0.22 and 0.15 mg/L for the high- and low-exposure subgroups, respectively. Linear regression analysis of individual semen parameters revealed a significant reduction of sperm concentration (35.9 x 10(6) vs 62.8 x 10(6), p < 0.01) and percentage of motility (47% vs 57%, p = 0.03) but not percentage of sperm with normal structure (57% vs 61%, p = 0.13). Multivariate modeling showed a significant overall shift in the mean semen parameter. Occupational exposure to ethylparathion and methamidophos seems to have a moderately adverse effect on semen quality.

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↗