Long-term tobacco smoking and colorectal cancer in a prospective cohort study.

Tobacco smoking has consistently been associated with colorectal adenomas, precursors of cancer, but the association with colorectal cancer itself has not been consistent. If colorectal cancer emerges only after a 35-year induction period, an association would unlikely be detected in studies where exposure assessment is of shorter duration. Most previous studies do not examine smoking of such duration and therefore do not account for the hypothesized 35-year induction period.

A pooled analysis of magnetic fields and childhood leukaemia.

Previous studies have suggested an association between exposure to 50-60 Hz magnetic fields (EMF) and childhood leukaemia. We conducted a pooled analysis based on individual records from nine studies, including the most recent ones. Studies with 24/48-hour magnetic field measurements or calculated magnetic fields were included.

Parental occupational exposure to magnetic fields and childhood cancer (Sweden).

Objectives: To test the hypothesis that parental occupational exposure to magnetic fields before conception and during pregnancy increases the risk of cancer in the offspring.

Methods: The study is designed as a cohort study based on a population of 235,635 children born shortly after two different censuses in Sweden. The children were followed from birth to 14 years and cases of cancer were identified in the Swedish cancer registry.

A Bayesian approach to hazard identification. The case of electromagnetic fields and cancer.

This paper discusses certain issues related to uncertainty in hazard identification. Research on the hypothesis that exposure to 50-60-Hz magnetic and electric fields (EMF) increases the risk of cancer has been ongoing for two decades. Epidemiological studies provide a somewhat consistent pattern indicating an increased risk for childhood leukemia and adult chronic lymphatic leukemia and possibly also for other leukemias and brain cancer.

Occupational and residential magnetic field exposure and breast cancer in females.

The purpose of this study was to evaluate the effect of occupational magnetic field exposure on breast cancer in females and to combine residential and occupational magnetic field exposure to reduce misclassification. The study was conducted as a case-control study within a population living within 300 meters of transmission lines in Sweden. We identified cases of breast cancer in females from the national cancer registry, and we selected one matched control per case at random.

Temporal characteristics of transmission-line loadings in the Swedish childhood cancer study.

A recent study conducted in Sweden reported that 1) leukemia risk in children who lived near 220 or 400 kV electric-power transmission lines was associated with calculated historical magnetic field levels; 2) children living within a distance of 50 m of transmission lines had an elevated risk of leukemia; and 3) there was no association between leukemia and residential magnetic fields measured many years after diagnosis. Subsequently, these investigators found through logistic regression analysis that disease was more strongly associated with calculated historical fields than with distance. Since the calculated historical fields in that study depended predominantly on distance and transmission-line load current, the logistic regression results suggest that historical load current plays an important role in the epidemiological results.

Reduced cancer incidence among the blind.

Melatonin is a hormone primarily produced by the pineal gland at night and is suppressed by exposure to light. Experimental studies have indicated that melatonin may protect against cancer development. In the majority of totally blind people, melatonin is never suppressed by light exposure.

Magnetic fields and breast cancer in Swedish adults residing near high-voltage power lines.

We conducted a case-control study to test the hypothesis that residential magnetic field exposures increase the incidence of breast cancer. The study was based on people who had lived within 300 m of 220- or 400-kV power lines in Sweden at any time between 1960 and 1985. We identified 699 cases of breast cancer in women and 9 cases in men.

Dementia and occupational exposure to magnetic fields.

Objectives: The purpose of the present report was to assess whether occupational magnetic field exposure is a risk factor for dementia, in particular for Alzheimer's disease.

Methods: Case-control analyses were applied to 77 dementia cases, 55 of whom had Alzheimer's disease, ascertained from the population-based Swedish twin register. Two reference groups were derived, with 228 and 238 persons, respectively.

Exposure to motor vehicle exhaust and childhood cancer.

Objectives: A case-referent study was conducted to test the hypothesis that exposure to motor vehicle exhaust increases the risk of childhood cancer.

Methods: Data from a study of residential magnetic field exposure and childhood cancer were used. From a population of 127000 children living within 300 m of transmission lines in Sweden, 142 cases of childhood cancer were identified, including 39 cases of leukemia and 33 cases of central nervous system tumor.

Occupational and residential magnetic field exposure and leukemia and central nervous system tumors.

Studies of magnetic field exposure and cancer have focused on either residential or occupational exposure. We conducted a case-control study taking into account both exposure sources. We identified leukemia and central nervous system tumor cases and controls from a population living within 300 m of transmission lines in Sweden.

Cancer in twins: genetic and nongenetic familial risk factors.

Background: Familial clustering has been observed for cancers that occur at specific sites. Most findings, which leave little doubt about the involvement of a heritable (i.e.

Occupational exposure to electromagnetic fields and adult leukaemia: a review of the epidemiological evidence.

The relationship between occupational exposure to extremely low-frequency electromagnetic fields and adult leukaemia has been studied extensively during the last decade. The first studies were based on crude exposure assessments, estimated through job titles, with no or only limited control confounding factors. The results were often inconsistent, indicating no effects in about 50% of the studies, while the other half showed only small to moderate effects.

Estimating exposure in studies of residential magnetic fields and cancer: importance of short-term variability, time interval between diagnosis and measurement, and distance to power line.

Validity of exposure assessment methods has been a major concern in epidemiologic studies of magnetic field exposure and cancer. We conducted a study to evaluate the relative importance of distance to power lines and calculated historical magnetic fields when estimating past magnetic field exposure. Another goal was to compare results based on various estimates of magnetic field exposure, to assess the importance of short-term variability in magnetic fields, time between diagnosis and measurement, and sources of magnetic field exposure.

Magnetic fields and childhood cancer--a pooled analysis of two Scandinavian studies.

To test the hypothesis that exposure to magnetic fields, of the type generated by high voltage installations, increases cancer incidence in children, the original data from two case-control studies were pooled. The Swedish study was based on children living within 300 m from transmission lines, and the Danish study on the total population of Denmark. In both these studies, national cancer registries were used to identify cases of leukaemia, lymphoma or central nervous system tumour.

Childhood leukemia and residential exposure to weak extremely low frequency magnetic fields.

There is no known mechanism by which magnetic fields of the type generated by high voltage power lines can play a role in cancer development. Nevertheless, epidemiologic research has rather consistently found associations between residential magnetic field exposure and cancer. This is most evident for leukemia in children.

Magnetic fields, leukemia, and central nervous system tumors in Swedish adults residing near high-voltage power lines.

We conducted a case-control study to test the hypothesis that exposure to magnetic fields of the type generated by high-voltage power lines increases the incidence of leukemia and central nervous system tumors in adults. The study was based on people who, between 1960 and 1985, had lived on a property in Sweden located within 300 meters of 220 or 400 kilovolt power lines. We identified a total of 325 leukemia cases and 223 cases of central nervous system tumor.