Biomedical subjects

R Kavet

Publications and source records attributed to R Kavet.

40 records · Page 3Linked to original sources

PubMed1991

An alternate hypothesis for the association between electrical wiring configurations and cancer.

Several epidemiologic studies have reported positive associations between electric distribution wiring configurations and cancer incidence, particularly among children. According to the investigators of these studies, the results indicate a possible link between cancer and exposure to 60-Hz magnetic fields, because residential magnetic fields are correlated with wiring configurations. I propose an alternate hypothesis to explain the epidemiologic observations, namely, that ground return currents in plumbing service lines are associated with electric wiring configuration, and cause the release of corrosion products in tap water, ingestion of which constitutes a risk factor for cancer. To corroborate this hypothesis, three conditions must be satisfied: (1) the magnitude of the ground return currents in water pipes is related to wiring configuration, with higher currents generally found associated with homes classified in the high-exposure categories; (2) corrosion on the internal surface of water pipe is related to alternating currents flowing on the pipe, with higher currents associated with higher rates of corrosion; and (3) ingestion of water from pipes undergoing alternating-current-related corrosive processes increases the probability of developing cancer.

Electric Wiring↗

PubMed1991

VDTs: field levels, epidemiology, and laboratory studies.

As the use of video display terminals (VDTs) has expanded, questions have been raised as to whether working at a VDT affects the risk of adverse pregnancy outcome. A particular focus for these questions has been the very low frequency (VLF) magnetic field produced by a VDT's horizontal deflection coil. VDTs also produce VLF electric fields, extremely low frequency (ELF) electric and magnetic fields, and static electric fields, Ten studies of pregnancy outcome in VDT operators have been conducted in six countries, and with one exception, none has concluded that magnetic fields from VDTs may predispose pregnant operators to spontaneous abortion or congenital malformation. The epidemiologic studies conducted thus far do not provide a basis for concluding that VDT work and adverse pregnancy outcome are associated. Studies of fetal resorptions and malformations in rodents exposed to VLF magnetic fields have produced inconsistent findings. Two laboratories in Sweden that studied mice have reported positive results, one laboratory showing field-related malformations (but not resorptions) and the other showing field-related resorptions (but not malformations). Two Canadian laboratories have reported negative results in rats and mice. Studies of avian embryos have also yielded inconsistent results, but lacking a maternal-fetal placental interface, avian embryos are a questionable model for evaluating human reproductive risks. Finally, VLF electric and magnetic fields measured at the operator position are in compliance with field strength standards and guidelines that have been established around the world.

Animals↗

PubMed1990

The toxicity of inhaled methanol vapors.

Methanol could become a major automotive fuel in the U.S., and its use may result in increased exposure of the public to methanol vapor. Nearly all of the available information on methanol toxicity in humans relates to the consequences of acute, rather than chronic, exposures. Acute methanol toxicity evolves in a well-understood pattern and consists of an uncompensated metabolic acidosis with superimposed toxicity to the visual system. The toxic properties of methanol are rooted in the factors that govern both the conversion of methanol to formic acid and the subsequent metabolism of formate to carbon dioxide in the folate pathway. In short, the toxic syndrome sets in if formate generation continues at a rate that exceeds its rate of metabolism. Current evidence indicates that formate accumulation will not challenge the metabolic capacity of the folate pathway at the anticipated levels of exposure to automotive methanol vapor.

Administration, Inhalation↗

PubMedDate not supplied

Modeling magnetic fields in residences: validation of the resicalc program.

RESICALC is a computer program that models magnetic fields due to currents on arbitrary arrays and configurations of electric transmission lines, primary and secondary distribution lines, and ground and neutral return pathways. The program conducts network analyses of ground/neutral currents in neighborhoods based on residential loads and impedances in the current path. Experiments were conducted at the Magnetic Field Research Facility (MFRF) in Lenox, Massachusetts to validate the program's field computation. MFRF has a simulated residential electric distribution system that permits the testing of scenarios with a broad range of electrical characteristics. The results demonstrate that the program accurately models fields from complex combinations of supply and ground/neutral currents, and shows how estimated fields may be sensitive to impedance values assigned to the ground and neutral currents. The program has usefulness as an exposure assessment tool when access to residences is not possible, and as a means to estimate fields when planning electrical facility or residential development. Careful mapping of power line and residential coordinates in the program, as well as acquiring the highest quality load and grounding data available, are critical for modeling valid exposure estimates.

Computer Simulation↗