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Biomedical subjects

E Leeper

Publications and source records attributed to E Leeper.

14 recordsLinked to original sources
PubMed1995

Childhood cancer in relation to indicators of magnetic fields from ground current sources.

This study examines childhood cancer risk in relation to certain factors likely to indicate magnetic field exposure from ground currents in the home. Substantial ground currents are most often found in homes having conductive plumbing, in which an uninterrupted metallic path in the water pipes and water main connects the grounding systems of neighboring houses. Information on plumbing conductivity was obtained from water suppliers for the homes of 347 cases and 277 controls identified in an earlier study of magnetic field exposure and childhood cancer in the Denver area. An increased cancer risk was observed for children in homes with conductive plumbing: The matched odds ratio was 1.72 (1.03-2.88) and increased to 3.00 (1.33-6.76) when analysis was limited to cases and controls who were residentially stable from the reference date to the study date. A measurement metric likely to indicate active ground currents (measurements having above-median intensity and a nonvertical orientation of < 55 degrees from the horizontal) was identified. In contrast to measured field intensity alone, for which only modest associations with cancer have been reported, this metric shows a high and significant cancer risk [matched O.R. = 4.0 (1.6-10.0)] consistent over a range of intensity and angle cutpoints. Such elevated nonvertical fields were also associated with cancer in an independent data set, which was gathered to study adult nonlymphocytic leukemia in the Seattle area. The associations of cancer with conductive plumbing and with this exposure metric both suggest that cancer risk is increased among persons with elevated magnetic field exposure from residential ground currents.

Adolescent↗
PubMed1991

Modification of the 1979 "Denver wire code" for different wire or plumbing types.

This article examines "wire configuration coding" as used to estimate relative residential AC magnetic field exposure in epidemiological studies--and the need to alter such coding for time or locations other than those in which the code was developed. Effects of different secondary wire practices are particularly examined.

Colorado↗
PubMed1989

Fetal loss associated with two seasonal sources of electromagnetic field exposure.

We have studied two sources of electromagnetic fields where exposure is highly seasonal (ceiling cable electric heat and electrically heated beds). Because many potential confounders could not be addressed, we can make no valid statement about overall differences in abortion rates between those exposed and those not exposed to these seasonal sources. However, by analyzing seasonal trends, we have minimized the problem of unaddressed confounders because we did not look at a difference between the user and nonuser groups, but rather at a difference within the user group during months of higher exposure compared with months of lower exposure. Thus, each user group provides its own control. The function of the nonuser control group is simply to assure that any seasonal trend found in the user group is not just a general seasonal variation in reported fetal loss that can be found equally well in the nonuser population. Using this technique, we found that each user group reported fetal loss disproportionately often during the season when electromagnetic field exposure was increasing.

Abortion, Spontaneous↗
PubMed1989

Re: "Acute Nonlymphocytic Leukemia and Residential Exposure to Power-Frequency Magnetic Fields".

The analyses presented here are available in greater detail elsewhere. They are not the analyses used to present the data in the original report, but we believe that they are reasonable analyses, suggested by the study's own measurement data, earlier published findings, and consideration of the likely sources of chronic residential magnetic field exposure among adults in the Washington State locale. If the association of magnetic field exposure with acute nonlymphocytic leukemia indicated by the analyses in table 1 is causal (and that is an important "if"), then the data suggest that some 25 per cent or more of these cases in the Washington State locale could be attributable to chronic magnetic field exposure--and that would obviously be a very important consequence. The risk, if real, is not trivial. And since protection from some important sources of exposure (such as electric bed heaters) is easily obtained, it seems hard to find any justification for not pursuing further studies of this subject immediately and vigorously.

Adult↗
PubMed1987

Magnetic field exposure related to cancer subtypes.

Certain subtypes of cancer (notably nervous system cancer) showed an association with two indices of exposure to 60-Hz alternating magnetic fields (AMFs): Subtype similarities were seen in those people potentially exposed to AMFs by their occupations, and in those potentially exposed by high-current power lines near their homes. The incidence-age patterns observed in exposed and nonexposed groups suggest that prolonged AMF exposure may act as a cancer promoter.

Adult↗
PubMed1986

Possible effects of electric blankets and heated waterbeds on fetal development.

Seasonal patterns were seen in fetal growth and in abortion rate for families using electrically heated beds. These patterns could be attributed to the seasonal use of heated beds. The fact that such seasonal patterns were seen only in users, and not in nonusers, of electrically heated beds suggests that electrical bed heating may have a direct effect on fetal development. The effect could be due to excessive heat or to electromagnetic field exposure.

Abortion, Spontaneous↗
PubMed1982

Adult cancer related to electrical wires near the home.

Like childhood cancer, adult cancer was found to be associated with high-current electrical wiring configurations (HCCs) near the patient's residence. Such wiring can expose occupants of the residence to alternating magnetic fields (AMFs) at a level which, though very low, may produce physiological effects. Several patterns in the data suggest that HCCs and cancer may be causally linked: (1) a dose-relationship was found. (2) The association did not appear to be an artefact of age, urbanicity, neighbourhood, or socioeconomic level. (3) The association was most clearly demonstrable where cancer caused by urban/industrial factors was least apt to obscure the effect. (4) A distinct pattern of latency between first exposure to the HCC and cancer diagnosis was seen, which is consistent with a hypothesis of cancer promotion produced by AMF exposure.

Adolescent↗
PubMed1979

Electrical wiring configurations and childhood cancer.

An excess of electrical wiring configurations suggestive of high current-flow was noted in Colorado in 1976--1977 near the homes of children who developed cancer, as compared to the homes of control children. The finding was strongest for children who had spent their entire lives at the same address, and it appeared to be dose-related. It did not seem to be an artifact of neighborhood, street congestion, social class, or family structure. The reason for the correlation is uncertain; possible effects of current in the water pipes or of AC magnetic fields are suggested.

Adolescent↗