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Biomedical subjects

D A Savitz

Publications and source records attributed to D A Savitz.

At least 127 records · Page 7Linked to original sources
PubMed1995

Intrauterine growth retardation as an endpoint in mutation epidemiology: an evaluation based on paternal age.

Czeizel recently suggested that intrauterine growth retardation might be of value as a phenotypic endpoint in mutation epidemiology. We hypothesized that if some fraction of small-for-gestational age (SGA) births are due to new germinal mutations, then an association with advanced paternal age should be present. We evaluated the relation between paternal age and SGA, low birthweight, and preterm births using a large sample of births (n = 254,892) from North Carolina. The analyses were restricted to births of mothers aged 20-34 years and adjusted for maternal age, race, education, marital status, gravidity, and smoking. No material increase in the risk of SGA, low birthweight, and preterm delivery was found for fathers in any age category. For example, odds ratios for SGA ranged from 0.87 (fathers aged 50 years or greater) to 1.13 (fathers aged 45-49 years). The results indicate no discernable relationship between SGA and related endpoints and the increase in increase of mutations that accompany advanced paternal age.

Adolescent↗
PubMed1995

Effect of hypertensive diseases in pregnancy on birthweight, gestational duration, and small-for-gestational-age births.

We measured the impact of hypertensive disorders in pregnancy (chronic hypertension, pregnancy-induced hypertension, and eclampsia) on birthweight, gestational duration, and small-for-gestational-age births. We employed a retrospective cohort design using North Carolina birth certificate data for the years 1988-1990, with the analyses based on nearly 300,000 pregnancies. Women noted to have eclampsia during pregnancy had a substantially greater risk of delivering very-low-birthweight infants (birthweight < or = 1,499 gm; risk difference (RD) = 6.7%) and moderately-low-birthweight infants (1,500-2,499 gm; RD = 14.6%), and very preterm (gestational age < 33 weeks; RD = 7.1%) and moderately preterm (33-36 weeks; RD = 9.3%) births, compared with women without hypertension. Corresponding risk differences for these outcomes were 1.9% and 5.1% for very low and moderately low birthweight, and 1.6% and 3.0% for very preterm and moderately preterm for women with chronic hypertension. Risk differences were of similar magnitude for women with pregnancy-induced hypertension for these outcomes. Hypertensive disorders in pregnancy were associated with small-for-gestational-age infants, with risk differences of 5.1%, 3.5%, and 9.2% for chronic hypertension, pregnancy-induced hypertension, and eclampsia, respectively. The patterns of risk were similar for preterm births due to spontaneous onset of labor and those due to other precipitating events. We observed similar patterns for black and white women. Control for confounders through multivariable logistic regression models did not alter the observed patterns. In spite of the limited data quality, we found that hypertensive disorders in pregnancy substantially increase the risk of low birthweight, preterm births, and small-for-gestational-age births.

Adult↗
PubMed1995

Occupation and cervical cancer.

Data collected for a multicenter case-control study of invasive cervical cancer and carcinoma in situ of the cervix were analyzed with regard to occupation. Odds ratios comparing 481 invasive cases and 293 carcinoma in situ cases to 801 controls were calculated and adjusted for potential confounding factors. Working women and homemakers had a similar risk of invasive cervical cancer, with several groups of service and industrial workers showing elevated risks (particularly maids, cleaners, and cooks). Risk of carcinoma in situ was slightly increased for working women, but no occupational groups had notable associations. The principal strengths of this analysis were the ability to address both invasive cervical cancer and carcinoma in situ and to control for multiple potential confounding factors. However, occupational information was limited and risk estimates for women in specific occupations were imprecise.

Adult↗
PubMed1995

Racial differences in the patterns of preterm delivery in central North Carolina, USA.

In order to assess racial differences in rates of idiopathic preterm labour, preterm premature rupture of membranes, and medically indicated preterm delivery, the authors analysed data on 388 preterm (< 37 completed weeks of gestation) births (7.9% of all births) occurring between 1 September 1988 and 31 August 1989, in three central North Carolina counties. The crude relative risk (RR) of preterm birth among black women compared with white women was 2.6 [95% confidence interval (CI) 2.1, 3.1]. With adjustment for age, gravidity, marital status, education, and county of residence, the estimated relative risk for black women compared with white women was 2.1 (95% CI 1.1, 4.1) for medically indicated preterm delivery, 1.6 (95% CI 1.1, 2.3) for preterm birth as a result of preterm labour, and 1.9 (95% CI 1.2, 3.1) for preterm premature rupture of membranes. Compared with white women, black women were at the highest risk of a preterm birth before 34 weeks of gestation (RR = 2.9; 95% CI 1.8, 4.7). The risk of medically indicated preterm delivery at 36 weeks was considerably higher for black women than for white women (RR = 3.4; 95% CI 1.1, 10.2). For a better understanding and ultimately a reduction of the risk for preterm delivery among black women, investigation of specific aetiological pathways and gestational age groups may be required.

Adolescent↗
PubMed1995

Drinking water and pregnancy outcome in central North Carolina: source, amount, and trihalomethane levels.

In spite of the recognition of potentially toxic chemicals in chlorinated drinking water, few studies have evaluated reproductive health consequences of such exposure. Using data from a case-control study of miscarriage, preterm delivery, and low birth weight in central North Carolina, we evaluated risk associated with water source, amount, and trihalomethane (THM) concentration. Water source was not related to any of those pregnancy outcomes, but an increasing amount of ingested water was associated with decreased risks of all three outcomes (odds ratios around 1.5 for 0 glasses per day relative to 1-3 glasses per day, falling to 0.8 for 4+ glasses per day). THM concentration and dose (concentration x amount) were not related to pregnancy outcome, with the possible exception of an increased risk of miscarriage in the highest sextile of THM concentration (adjusted odds ratio = 2.8, 95% confidence interval = 1.1-2.7), which was not part of an overall dose-response gradient. These data do not indicate a strong association between chlorination by-products and adverse pregnancy outcome, but given the limited quality of our exposure assessment and the increased miscarriage risk in the highest exposure group, more refined evaluation is warranted.

Case-Control Studies↗
PubMed1995

Overview of occupational exposure to electric and magnetic fields and cancer: advancements in exposure assessment.

For over ten years, there has been concern with the potential for increased risk of cancer among "electrical workers." In contrast to studies of residential exposure to magnetic fields, occupational studies include electric and magnetic field exposures and have much greater variability in field intensity, frequency, and temporal patterns. Studies of leukemia in electrical workers show a moderate consistency, with elevated risk ratios of 1.2 to 2.0 commonly observed. Brain tumors are similarly elevated with some consistency, and three recent studies have suggested increased risk of male breast cancer. Retrospective exposure assessment methods were advanced in recent studies of diverse occupations in a study in central Sweden, which yielded evidence of increased risk of chronic lymphocytic leukemia among men in more highly exposed occupations. A study of telephone workers in New York State incorporated measurements and found some indication of increased leukemia risk only when exposures were based on historical technology. Utility workers in southern California were studied and found not to have increased risks of leukemia and brain cancer based on exposures estimated with measurements. An ongoing study of electric utility workers at five companies in the United States incorporates an extensive measurement protocol. Randomly selected workers within occupational categories wore a time-integrating magnetic-field meter to provide estimates of exposure for the occupational category. We were able to estimate and partition the variance into between-day (the largest contributor), within occupational categories, and between occupational categories. Principal research needs concern optimal levels of worker aggregation for exposure assignment, historical extrapolation, study of diverse work environments, and integration of residential and occupational exposure in the same study.

Electromagnetic Fields↗
PubMed1995

Home pesticide use and childhood cancer: a case-control study.

The association between childhood cancer and home pesticide use was examined in a case-control study of children under 15 years of age. Parents of 252 children diagnosed with cancer in the Denver area between 1976 and 1983 and of 222 control subjects were interviewed regarding use of home pest extermination, yard treatment, and pest strips. The strongest associations were found for yard treatments and soft tissue sarcomas (odds ratios [ORs] around 4.0) and for use of pest strips and leukemias (ORs between 1.7 and 3.0). These results suggest that use of home pesticides may be associated with some types of childhood cancer.

Adolescent↗
PubMed1995

Hypertensive disorders of pregnancy and stillbirth in North Carolina, 1988 to 1991.

BACKGROUND: The objectives of this study were (i) to assess the effect of hypertensive disorders of pregnancy on the risk of stillbirth, and (ii) to characterize the relationship between hypertension and stillbirth separately by gravidity, race, 'explained' versus 'unexplained' causes of stillbirth, and antepartum versus intrapartum stillbirths. METHODS: The study was based on a retrospective cohort of approximately 400,000 pregnancies identified through the birth and fetal death certificates in North Carolina, USA, between 1988 and 1991. Multivariable polytomous logistic regression was used to generate odds ratios comparing stillbirth risk in hypertensive compared to non-hypertensive mothers, adjusted for potential confounders. RESULTS: The risk of chronic hypertension was 7.6 per 1000 pregnancies, while pregnancy-induced hypertension (PIH) and eclampsia were reported in 36.6 and 6.0 per 1000 pregnancies, respectively. Pregnancies among chronic hypertensives were more likely to result in losses after 28 weeks gestation (RR = 3.29, 95% CI: 2.43-4.43), while the risk ratio was 2.16 (95% CI: 1.45-3.22) for losses prior to 28 weeks' gestation. Pregnancies to patients with PIH were at 1.42 (95% CI: 1.15-1.79) times greater risk of terminating in late stillbirth, while the risk ratio for eclampsia was 2.23 (95% CI: 1.51-3.30). The risk ratio for 'explained' antepartum stillbirth was higher than intrapartum stillbirth for all of the hypertensive diseases. CONCLUSIONS: Hypertensive disorders were found to have a strong adverse impact on stillbirth suggesting that early diagnosis of hypertension during pregnancy and adequate medical intervention may help reduce the risk of stillbirth.

Chronic Disease↗
PubMed1995

Assessment and grouping of occupational magnetic field exposure in five electric utility companies.

OBJECTIVES: Occupational exposure to 60-Hz magnetic fields was surveyed among randomly selected workers in five electric power companies. METHODS: The study facilitated the examination of exposure variability and provided the base for a job-exposure matrix linking health outcomes and occupational magnetic field exposures. RESULTS: Average exposures ranged from 0.11 to 1.50 microT. The differences among the five companies were small, the more urban companies showing somewhat higher averages. The day-to-day component of variance exceeded the within- and between-group components of variance. The final job-exposure matrix consisted of five groups with average exposure levels of 0.12, 0.21, 0.39, 0.62, and 1.27 microT. Given the variance in exposure, even this optimal grouping considerably overlapped. CONCLUSIONS: The job-exposure matrix used in this study efficiently incorporated the differences in exposure within occupational categories between companies and provided an objective and statistically based method for estimating cumulative magnetic field exposure.

Adult↗
PubMed1994

Breast cancer mortality among female electrical workers in the United States.

BACKGROUND: Previous epidemiologic studies have suggested that exposure to electric or magnetic fields in occupational and residential environments may cause cancer. Recent experimental findings provide some support for the hypothesis that exposure to extremely low-frequency electromagnetic fields reduces the pineal gland's nocturnal production of the hormone melatonin, thereby increasing susceptibility to sex hormone-related cancers such as breast cancer. PURPOSE: Our purpose was to assess the evidence that cancer of the female breast might be associated with exposure to extremely low-frequency electromagnetic fields. METHODS: Records of women who had breast cancer as the underlying cause of their death (ICD-9 174) and control subjects (four per case) were selected from computer files of U.S. mortality data for the years 1985-1989. Women 20 years and older at the time of their death were eligible for inclusion if they were residents of and died in one of the 24 states that provided death certification records with occupation and industry codes to the National Center for Health Statistics for at least 1 year during the study interval. Data from death certificates were used to classify the case and control subjects with regard to potential occupational exposure to electric and magnetic fields. Control subjects were a random sample of women who died of any other underlying cause, excluding leukemia and brain cancer. RESULTS: The data analysis contrasted 68 women with breast cancer and 199 controls, all with electrical occupations, with 27,814 women with breast cancer and 110,750 controls, all of whom had other occupations. Electrical workers had excess mortality from breast cancer relative to other employed women [odds ratio (OR) = 1.38; 95% confidence interval (CI) = 1.04-1.82]). Adjusted ORs for specific electrical occupations were 1.73 (95% CI = 0.92-3.25) for electrical engineers, 1.28 (95% CI = 0.79-2.07) for electrical technicians, and 2.17 (95% CI = 1.17-4.02) for telephone installers, repairers, and line workers. There was no excess of breast cancer, however, in seven other occupations held more frequently by women and also involving potentially elevated electrical exposures, including telephone operators, data keyers, and computer operators and programmers. CONCLUSIONS: In light of the limitations inherent in death certification data and the design of this study, any conclusions regarding the hypothesis that exposure to extremely low-frequency electromagnetic fields causes breast cancer among women must be limited. Nevertheless, our findings are broadly consistent with that hypothesis and encourage further investigation with improvements in study design and data quality.

Adult↗
PubMed1994

Medically treated miscarriage in Alamance County, North Carolina, 1988-1991.

The authors attempted to identify all medically treated miscarriages in Alamance County, North Carolina, between September 1988 and August 1991. Clinical and demographic characteristics of the cases were evaluated, and risks were calculated in relation to total pregnancies, including induced abortions. Miscarriage cases usually had positive pregnancy tests, and a sizable proportion (66% of whites, 72% of blacks) had a pathology report indicating the presence of a conceptus. Nineteen percent of the cases were identified in hospitals, a more common source for women who were unmarried, young, of low education, and had pregnancies of advanced gestational age. The risk of medically treated miscarriage was 7.7% among whites and 5.5% among blacks, with higher risks among older women. The lower risk among blacks, especially those with lower levels of education, suggests underascertainment, possibly resulting from a failure to seek treatment.

Abortion, Spontaneous↗
PubMed1994

Statistical significance testing in the American Journal of Epidemiology, 1970-1990.

Despite persistent controversy over statistical significance testing and the obligation for all researchers to adopt some position on the issue, until now, practices of epidemiologists have not been examined thoroughly. Articles in the American Journal of Epidemiology around the years 1970, 1980, and 1990 were evaluated and divided into infectious disease epidemiology, cancer epidemiology, and cardiovascular disease epidemiology, with a minimum of 25 articles per topic area and time period. Presentation of significance test results and confidence intervals was evaluated in the abstracts, results text, and results tables, as was the degree of reliance on significance testing in the discussion section. Significance testing grew markedly in infectious disease epidemiology and was consistently high in cardiovascular disease and cancer epidemiology. Confidence intervals were virtually absent in 1970 and became ubiquitous (particularly in cancer epidemiology) by 1990, when the most common practice was to provide confidence intervals in results tables and to emphasize statistical significance tests in results text. Reliance on statistical significance tests in interpretation grew steadily in infectious disease, sustained a high level in cardiovascular disease, and declined after 1980 in cancer epidemiology. At present, dual presentation of confidence intervals and statistical test results is dominant.

Cardiovascular Diseases↗
PubMed1994

Prevalence of depression among electrical workers.

To address the possible association between electric and magnetic field exposure and depression, we analyzed data from the Vietnam Experience Study. In order to compare the risk of diagnosed depression, depressive symptoms, and elevations in personality scales indicative of depression, we classified employed participants as electrical workers (N = 183) and nonelectrical workers (N = 3,861) and compared their scores on the Diagnostic Interview Survey (DIS) and the Minnesota Multiphasic Personality Inventory (MMPI). Electrical workers in the aggregate showed little evidence of increased risk, with the possible exception of an increase in elevated MMPI depression scores among short-term workers. Data on electricians yielded indications of increased risk for several markers of depression. Despite the limited number of electrical workers, uncertainty regarding exposure, and our inability to address other workplace exposures, these results suggest that electrical workers in general are not at increased risk for depression. However, our results encourage further evaluation of depression among electricians.

Adult↗
PubMed1994

Study of occupational risk factors for pregnancy-induced hypertension among active duty enlisted Navy personnel.

The relationship between occupational exposures and the risk of pregnancy-induced hypertension (PIH) was investigated in a cohort of 5,605 enlisted active duty military women who gave birth during a 2-year period of time. A panel of experts, unaware of disease status, classified the women's job titles as "high," "medium," or "low" for a variety of occupational exposures. PIH was identified through hospital discharge ICD-9 diagnosis codes. Nulliparas were found to have a significantly increased risk ratio (RR) for PIH (RR = 2.3) compared with parous women. Nulliparas employed in jobs involving high levels of physical activity were at significantly decreased risk of PIH compared to nulliparas working at low levels of physical activity (construction craftsmen, RR = 0.37; unskilled laborers RR = 0.71). Occupational exposure to hazardous chemicals was not related to risk of PIH. Although the study results are limited by aggregate exposure classification, they suggest no adverse influence of occupational exertion and a possible beneficial role among nulliparas.

Adult↗
PubMed1994

Review of epidemiologic studies of paternal occupational exposure and spontaneous abortion.

The question of whether paternal exposures influence risk of spontaneous abortion is of great public interest, with the possibility supported by laboratory investigations. Thirty-nine studies of male occupational exposure and risk of spontaneous abortion were examined, with the methods and results tabulated. Many of those reports were limited by exposure data based on maternal report of the father's job title or by potentially inaccurate paternal reports of spontaneous abortion, though the quality of more recent studies is markedly enhanced. Mercury has been implicated most strongly based on recent studies that included quantitative exposure estimates; a number of studies showing associations for exposure to anesthetic gases. Suggestive associations have also been found inconsistently for exposure to lead, rubber manufacturing, selected solvents, and some pesticides. Further study is encouraged, but with more intensive effort to measure accurately both spontaneous abortion and occupational exposures.

Abortion, Spontaneous↗