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Biomedical subjects

D A Savitz

Publications and source records attributed to D A Savitz.

At least 217 records · Page 12Linked to original sources
PubMed1987

Leukemia and occupational exposure to electromagnetic fields: review of epidemiologic surveys.

Several recent surveys have presented data suggesting an increased risk of leukemia among men with occupational exposure to electromagnetic fields. Eleven pertinent data sets were compiled in order to assess the consistency of this pattern and to identify those occupations most deserving closer examination. Results for total leukemia show a modest excess risk for men in exposed occupations, with an enhanced risk elevation for acute leukemia and especially acute myelogenous leukemia. These studies are inherently limited regarding the effect of electromagnetic fields due to the absence of exposure characterization. Nonetheless, telegraph, radio, and radar operators, power and telephone linemen, and electrical and electronic engineers showed the most consistent results and warrant further study to ascertain potential occupational health hazards.

Acute Disease↗
PubMed1986

Long-term use of oral contraceptives and risk of invasive cervical cancer.

To evaluate the relationship between use of oral contraceptives and risk of invasive cervical cancer, a case-control study involving 479 patients and 789 population controls was undertaken in 5 geographic regions of the US. Initially, the relationship was obscured by confounding variables, particularly the interval since last Pap smear. Control for this variable as well as for sexual and sociodemographic factors revealed an RR of 1.5 overall, with long-term users (5 or more years) being at a 2-fold higher risk than non-users. Pill associations prevailed for both adenocarcinomas and squamous-cell tumors, and risks were highest for those using pills containing high estrogen potencies. In addition, there was some evidence that pill associations were most pronounced among women who had never used barrier methods of contraception or who had histories of genital infections, suggesting that oral contraceptives may act as co-carcinogens with transmissible agents. Our findings provide further evidence that long-term use of oral contraceptives may have a carcinogenic effect on cervical epithelium, but emphasize the need for careful evaluation of confounding influences.

Adenocarcinoma↗
PubMed1986

Cigarette smoking and invasive cervical cancer.

A case-control study of 480 patients with invasive cervical cancer and 797 population controls, conducted in five geographic areas in the United States, included an evaluation of the relationship of several cigarette smoking variables to cervical cancer risk. Although smoking was correlated with both age at first intercourse and number of sexual partners, a significant smoking-related risk persisted for squamous cell carcinoma after adjustment for these factors (relative risk, 1.5). The risk of squamous cell cancers increased significantly with intensity and duration of smoking. Twofold excess risks were seen for those smoking 40 or more cigarettes per day and those smoking for 40 or more years. In addition, users of nonfilter cigarettes were at particularly high risk. Increased risks, however, were observed only among recent and continuous smokers. In contrast to squamous cell cancer, no relationship was observed between smoking and risk of adenocarcinoma or adenosquamous carcinoma (n = 63). These results suggest a causal relationship between cigarette smoking and invasive squamous cell cervical cancer, perhaps through a late-stage or promotional event, although the mechanisms of action require further elucidation.

Adenocarcinoma↗
PubMed1986

Changes in Spanish surname cancer rates relative to other whites, Denver area, 1969-71 to 1979-81.

Cancer incidence rates for persons of Spanish surname and other Whites in the Denver, Colorado area were derived for two time periods, 1969-71 and 1979-81. The substantial deficits in total cancers for Spanish surname males and females relative to other Whites in 1969-71 diminished considerably for all age groups by 1979-81. The major determinants of this pattern were the rapidly rising Spanish surname rates for cancer of the colon and rectum, lung cancer, kidney cancer, female breast and uterine cancers, and male prostate, bladder, and hematopoietic cancers. There was a convergence of Spanish surname rates toward the other White rates for nearly all sites, regardless of whether other Whites showed increasing, decreasing, or stable rates. Notable exceptions occurred for cervical cancer, which dropped more slowly among persons of Spanish surname than among other Whites, and Spanish surname female stomach cancer rates which rose during the 1970s in contrast to a decrease among other Whites. The overall pattern is consistent with acculturation of persons of Spanish surname towards the majority's lifestyle, suggesting the value of more detailed studies of specific cancer determinants in the Spanish surname population.

California↗
PubMed1985

Screening for geographic heterogeneity of disease rates: application to cancer incidence in Allegheny County, Pennsylvania, 1969-71.

A statistical technique for analyzing heterogeneity in rates proposed by Gail is potentially well-suited to the analysis of geographic patterns in disease incidence data. This was applied to 1969-71 cancer incidence in whites in 30 census tract aggregates within Allegheny County, Pennsylvania to ascertain its usefulness and to search for patterns. A product model, in which each area's risks are a constant multiple of one another across age groups, was found to adequately fit the observed data. The test for geographic heterogeneity indicated that 19 of 30 sex-site groupings manifested greater than chance variation across the county subunits, generally consistent with the number of outliers based on 95% confidence limits. Partitioning the heterogeneity in these sites by median income quintiles suggested a positive risk gradient with breast cancer (F) and negative risk gradients with rectal (M), pancreatic (F), lung (M), cervical (F), and bladder cancer (F). Percent foreign stock was positively associated with total cancer (M, F), colon (M, F), pancreatic (F), lung (M), and bladder cancer (M, F). The technique successfully demonstrated the accuracy of a product model, screened cancer sites meriting detailed study, and suggested several associations of median income and percent foreign stock with cancer risk.

Emigration and Immigration↗
PubMed1985

Determinants of medical record access for an epidemiologic study.

Hospital record access is often needed for epidemiologic research. In a recent study, 26 Denver-area hospitals were contacted for permission to review records. The review process, the decision regarding access, and hospital characteristics were analyzed. Hospitals with a review committee, larger hospitals, and those which reached a decision rapidly were most likely to grant access. These results may provide guidance to investigators planning studies requiring review of hospital records.

Colorado↗
PubMed1984

Survey of reproductive hazards among oil, chemical, and atomic workers exposed to halogenated hydrocarbons.

Several halogenated hydrocarbons are suspected of causing adverse reproductive effects. Because of such concerns, the Oil, Chemical, and Atomic Workers International Union surveyed the reproductive histories of two groups of workers. One group worked at plants engaged in the production or use of halogenated hydrocarbons (exposed) whereas the others had no such opportunity for exposure (nonexposed). Although a low response rate precludes firm conclusions, the 1,280 completed questionnaires provide useful data for generating hypotheses in this developing field of interest. A history of diagnosed cancer was reported more frequently among exposed workers. The infant mortality rate was also significantly elevated among the offspring of exposed workers. No risk gradient was observed for episodes of infertility, fetal loss, congenital defects, or low-birthweight offspring. Concerns with nonresponse, exposure characterization, possible confounding factors, and limited statistical power are addressed. The results provide further suggestions which help to direct studies of occupational reproductive risks.

Abnormalities, Drug-Induced↗
PubMed1984

Cancer risk among oil refinery workers. A review of epidemiologic studies.

The possibility that excess cancers result from occupational exposures in oil refineries has generated a great deal of interest. Ecological studies and case-control studies in the general population have suggested a positive association between oil industry activity and cancer rates, with more direct evidence provided by studies of refinery employees. The eight investigations of cancer risks among refinery employees are critically reviewed. The methodological strengths and weaknesses of these studies are evaluated with an emphasis on the likely impact on the results. While the results are markedly inconsistent across studies, there is some suggestion of excess risks for melanoma and for brain, stomach, kidney, and pancreatic cancers. Problems with exposure characterization, latency, and potential confounding factors limit all of the studies that were reviewed.

Adult↗
PubMedDate not supplied

Resistance of fetal membranes to concentrated force applications and reconciliation of puncture and burst testing.

To further the characterization of the chorioamniotic membrane's physical properties, we assessed its ability to withstand a concentrated force. Probes of various diameters were used to puncture 275 specimens from 11 membranes. Values for "strength"/thickness, "stiffness"/thickness, and "toughness"/thickness all showed positive linear correlations (p < 0.001) with the increase of d/D, the ratio of probe diameter to specimen diameter. "Ductility" was independent of diameter, though a logarithmic regression did fit the data marginally (p < 0.05). The separate fracture of the amnion and chorion, which is reflected in ductility measurements, results in an increase in the distance the membrane can be deflected in vitro. In vivo, this behavior would translate to a reduction of pressure exerted on the remaining membrane, while the integrity of the protective sac is maintained. The data pool of mechanical characteristics was enlarged by reconciling data that were gathered by either of two testing methods: puncturing or bursting; the latter method involves the application of force over the entire surface of the test specimen.

Elasticity↗
PubMedDate not supplied

Hospital setting for birth and use of medical procedures in low-risk women.

This study examined the use of selected medical procedures in low-risk women during childbirth. Data from the 1980 National Natality Survey merged with an American Hospital Association annual survey for the same year were used to assess the frequency with which low-risk women in the United States received certain childbirth procedures and to determine whether their use varied by the hospital setting for birth. Stratified analysis was used to assess the relation of hospital level for delivery with the use of electronic fetal monitoring, labor induction, and primary cesarean delivery in low-risk women, with control for potential confounding factors. As the level of available perinatal technology increased, the use of these procedures increased. Results of the study suggest that low-risk women may have received excess interventions and confirm the need for further examination of care procedures for this group.

Cesarean Section↗
PubMedDate not supplied

Assessment of reproductive disorders and birth defects in communities near hazardous chemical sites. I. Birth defects and developmental disorders.

Members of the workgroup on birth defects and developmental disorders discussed methods to assess structural anomalies, genetic changes and mutations, fetal and infant mortality, functional deficits, and impaired fetal and neonatal growth. Tier 1 assessments for all five adverse reproductive outcomes consist of questionnaires and reviews of medical records rather than laboratory testing of biologic specimens. The work-group members noted a role for neurodevelopmental testing and for limited genetic studies, such as karyotyping in Tier 2 assessments. Emerging methodologies to identify chromosomal aberrations, DNA adducts, and repair inhibition were reserved for Tier 3.

Adult↗
PubMedDate not supplied

Predictors of symptomatic urinary tract infection after 20 weeks' gestation.

OBJECTIVE: To identify predictors of symptomatic urinary tract infection (UTI) after 20 weeks' gestation. STUDY DESIGN: A retrospective cohort analysis was conducted of all deliveries at three North Carolina hospitals between 1990 and 1993. A total of 7403 deliveries remained after exclusions (pre-pregnancy diabetes, HIV-positive, structural urologic abnormalities, no prenatal care) and restrictions (black or white race, county of residence). Cystitis and pyelonephritis were identified by clinician diagnosis. Multiple logistic regression was conducted. RESULTS: Prior UTIs (both before and earlier in pregnancy), nonprivate clinics, and a history of chlamydia (white women only) doubled the risk of symptomatic UTIs after 20 weeks' gestation. The strongest predictor of pyelonephritis was prior antenatal UTIs (adjusted incidence odds ratio = 5.3, 95% confidence interval of 2.6-11.0), followed by less education (< 12 years), a history of chlamydia, nonprivate clinics, illicit drug use, sickle cell hemoglobinopathy, and being unmarried. CONCLUSION: Medical history and demographic factors predict cystitis and pyelonephritis after 20 weeks' gestation. Prospective studies of pyelonephritis predictors and screening strategies are warranted.

Adult↗
PubMedDate not supplied

Pulmonary function and ambient particulate matter: epidemiological evidence from NHANES I.

The relationship between pulmonary function and quarterly average levels of total suspended particulates (TSP) was examined for adults who resided in 49 of the locations where the First National Health and Nutrition Examination Survey (NHANES I) was conducted. Statistically significant relationships were observed between TSP levels and forced vital capacity (FVC) and forced expiratory volume at one second (FEV1.0). These relationships remained strong across several specifications and sample changes, e.g., exclusion of cities with two highest and two lowest TSP levels, restriction of sample to whites only. Anthropometric measurements and socioeconomic characteristics of the subjects were included in the analysis, and we restricted the sample to "never" smokers. The results indicate a 1 standard deviation increase (about 34 micrograms/m3) in TSP from the sample mean of 87 micrograms/m3 was associated with an average decrease in FVC of 2.25%. The results of this analysis also suggest that there is a threshold level (i.e., approximately 60 micrograms/m3 [quarterly average]) of TSP below which a relationship with pulmonary function ceases to exist.

Adult↗