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L I Kheifets

Publications and source records attributed to L I Kheifets.

10 recordsLinked to original sources
PubMed1999

Childhood brain tumors and residential electromagnetic fields (EMF).

There are many recent comprehensive reviews of the residential EMF epidemiologic literature, but they do not attempt to cover the issue of childhood brain tumors and EMF in depth. We present here background information on descriptive epidemiology of known or suspected causes of childhood brain tumors and a detailed review of studies that have examined the associations between EMF as represented by various surrogates, and childhood brain tumors. We evaluated nine studies of childhood brain tumors and residential exposure to EMF based on wire codes, distance, measurements, and modeling, and six studies that examined the use of appliances by children or their mothers during pregnancy. For each study we discussed analytical and methodological issues including choice of cutpoints, nonconcurrent control selection, random digit dialing, differential participation, and ability of a study to detect an association. On the basis of this comprehensive review of all available childhood brain cancer studies, we do not see support for an overall association between EMF and childhood brain cancer. This lack of support applied for all surrogates of past magnetic fields, including wire code, distance, measured or calculated fields, and use of appliances by either child or mother.

Brain Neoplasms↗
PubMed1999

The relationship between electromagnetic field and light exposures to melatonin and breast cancer risk: a review of the relevant literature.

Worldwide, breast cancer is the most common malignancy accounting for 20-32% of all female cancers. This review summarizes the peer-reviewed, published data pertinent to the hypothesis that increased breast cancer in industrialized countries is related to the increased use of electricity [Stevens, R.G., S. Davis 1996]. That hypothesis specifically proposes that increased exposure to light at night and electromagnetic fields (EMF) reduce melatonin production. Because some studies have shown that melatonin suppresses mammary tumorigenesis in rats and blocks estrogen-induced proliferation of human breast cancer cells in vitro, it is reasoned that decreased melatonin production leads to increased risk of breast cancer. To evaluate this hypothesis, the paper reviews epidemiological data on associations between electricity and breast cancer, and assesses the data on the effects of EMF exposure on melatonin physiology in both laboratory animals and humans. In addition, the results on the effects of melatonin on in vivo carcinogenesis in animals are detailed along with the controlled in vitro studies on melatonin's effects on human breast cancer cell lines. The literature is evaluated for strength of evidence, inter-relationships between various lines of evidence, and gaps in our knowledge. Based on the published data, it is currently unclear if EMF and electric light exposure are significant risk factors for breast cancer, but further study appears warranted. Given the ubiquitous nature of EMF and artificial light exposure along with the high incidence of breast cancer, even a small risk would have a substantial public health impact.

Animals↗
PubMed1997

Leukemia risk and occupational electric field exposure in Los Angeles County, California.

The authors analyzed data on electric fields from a prior study of occupational magnetic field exposure and leukemia risk conducted in Los Angeles County, California, in 1972-1990. Ranking of exposure differed somewhat for magnetic and electric fields. The odds ratios were 1.22 (95% confidence interval (CI) 0.80-1.86) and 1.15 (95% confidence interval 0.78-1.72) for medium and high exposure categories, respectively, and there was no clear evidence of an exposure-response relation (odds ratio for 10 V/m increase = 1.05, 95% CI 0.95-1.16). Although not conclusive, our analyses provide little support for an association between occupational electric field exposure and leukemia.

Adult↗
PubMed1997

Wire codes, magnetic fields, and childhood cancer.

Childhood cancer has been modestly associated with wire codes, an exposure surrogate for power frequency magnetic fields, but less consistently with measured fields. We analyzed data on the population distribution of wire codes and their relationship with several measured magnetic field metrics. In a given geographic area, there is a marked trend for decreased prevalence from low to high wire code categories, but there are differences between areas. For average measured fields, there is a positive relationship between the mean of the distributions and wire codes but a large overlap among the categories. Better discrimination is obtained for the extremes of the measurement values when comparing the highest and the lowest wire code categories. Instability of measurements, intermittent fields, or other exposure conditions do not appear to provide a viable explanation for the difference between wire codes and magnetic with respect to the strength and consistency of their respective association with childhood cancer.

Brain Neoplasms↗
PubMed1997

Occupational electric and magnetic field exposure and leukemia. A meta-analysis.

We conducted a meta-analysis to acquire an understanding of the association between leukemia and occupational exposure to electric and magnetic fields. To explore sources of heterogeneity, study characteristics were scored and examined using regression analysis. While most studies present a small elevation in risk, the apparent lack of a clear pattern of exposure to EMF and risk of leukemia substantially detracts from the hypothesis that measured magnetic fields in the work environment are responsible for the observed excess risk of leukemia. Findings were not sensitive to assumptions, influence of individual studies, weighting schemes, and modeling. Some evidence of publication bias is noted.

Bias↗
PubMed1995

Occupational electric and magnetic field exposure and brain cancer: a meta-analysis.

We conducted a meta-analysis to acquire an understanding of the association between central nervous system cancer and occupational exposure to electric and magnetic fields. To explore sources of heterogeneity, study characteristics were scored and examined using regression analysis. An inverse-variance weighted pooling leads to a small overall increase in relative risk (10 to 20%) for the broad group of electrical occupations. One of the largest differences was lower relative risk for Scandinavian studies. Lower relative risks were also reported in cohort- and incidence-based studies. Findings were not sensitive to assumptions, including unpublished data, influence of individual studies, weighting schemes, and modeling. Whereas most studies present a small elevation in risk, there is considerable heterogeneity among the results.

Brain Neoplasms↗
PubMed1993

Synthetic cancer variables and the construction and testing of synthetic risk maps.

Cancer cluster investigations are usually univariate in nature; they focus on a particular cancer, such as leukaemia, and attempt to determine whether excess risk is associated with a suspected cancer-causing agent. Although several causes of death (such as leukaemia, lymphoma, Hodgkin's) may be considered, the approach is univariate because the causes of death are analysed sequentially and independently of one another. This approach is consistent with a one-cause one-effect model. Rarely, however, is the action of a carcinogen manifested at only one body site, and correlations among causes of death are the norm rather than the exception. A multiple effects model is therefore appropriate, and the multivariate nature of cancer mortality data should be exploited when exploring geographic pattern in cancer risks. This paper describes such an approach. We construct maps based on a principal components analysis of cancer mortality rates from different geographic areas. The resulting principal components are called synthetic cancer variables (SCVs), and maps of the SCV scores are synthetic risk maps (SRMs). These maps quantify geographic variation in cancer risk at several body sites simultaneously, and may be analysed for (1) spatial structure and (2) geographic association with potential risk factors. As an example, we use synthetic risk maps to determine whether high-risk counties in Illinois cluster near nuclear facilities. Much work remains to be done, but synthetic cancer risk maps appear to be a useful tool for quantifying geographic pattern and multivariate structure in cancer mortality.

Air Pollutants, Radioactive↗
PubMedDate not supplied

Exposure assessment for power frequency electric and magnetic fields (EMF) and its application to epidemiologic studies.

Epidemiologic studies suggesting possible health effects associated with exposure to electric and magnetic fields (EMF) from the transmission, distribution, and use of electricity have motivated increased interest in and attention to EMF exposure assessment. The result has been new instruments, measurement approaches, and exposure models that can improve on what has been a weakness in past epidemiologic studies, namely EMF exposure assessment. This paper presents a status report on EMF exposure assessment that emphasizes the need for incorporation of these advances in future studies. Several factors are identified that make the assignment of contemporary or retrospective EMF exposures potentially more difficult than for other environmental agents. These include: EMF is not generally detectable by humans, exposure scenarios for EMF are generally not memorable, there is no clear mechanism for EMF effects, and the pervasive nature of EMF in an industrialized society makes identification of a low-exposure group difficult. Elements of study design that are impacted by the nature of EMF exposures include: sampling and measurement strategies, summary measures of exposure, and the choice of surrogate and/or models of exposure. Consideration of these exposure assessment issues and incorporation of recent advances can improve the overall quality of epidemiologic studies with an EMF exposure component.

Child↗