Most cancer in firefighters is due to radio-frequency radiation exposure not inhaled carcinogens.

Recent reviews and reports of cancer incidence and mortality in firefighters conclude that they are at an increased risk of a number of cancers. These include leukemia, multiple myeloma, non-Hodgkin's lymphoma, male breast cancer, malignant melanoma, and cancers of the brain, stomach, colon, rectum, prostate, urinary bladder, testes, and thyroid. Firefighters are exposed to a long list of recognized or probable carcinogens in combustion products and the presumed route of exposure to these carcinogens is by inhalation. Curiously, respiratory system cancers and diseases are usually not increased in firefighters as they are in workers exposed to known inhaled carcinogens. The list of cancers with increased risk in firefighters strongly overlaps the list of cancers at increased risk in workers exposed to electromagnetic fields (EMF) and radiofrequency radiation (RFR). Firefighters have increased exposure to RFR in the course of their work, from the mobile two-way radio communications devices which they routinely use while fighting fires, and at times from firehouse and fire vehicle radio transmitters. I suggest that some of the increased cancer risk in firefighters is caused by RFR exposure, and is therefore preventable. The precautionary principle should be applied to reduce the risk of cancer in firefighters, and workman's compensation rules will necessarily need to be modified.

Historical evidence that residential electrification caused the emergence of the childhood leukemia peak.

A peak in childhood leukemia, ages two through four, emerged de novo in the 1920s in the United Kingdom and slightly later in the United States (US). Electrification in US farm and rural areas lagged behind urban areas until 1956. In recent years, childhood leukemia has been associated with residential electromagnetic fields. During 1928-1932, in states with above 75% of residences served by electricity, leukemia mortality increased with age for single years 0-4, while states with electrification levels below 75% showed a decreasing trend with age (P = 0.009). During 1949-1951, all states showed a peak in leukemia mortality at ages 2-4. At ages 0-1, leukemia mortality was not related to electrification levels. At ages 2-4, there was a 24% (95% confidence interval (CI), 8%-41%) increase in leukemia mortality for a 10% increase in percent of homes served by electricity. The childhood leukemia peak of common acute lymphoblastic leukemia may be attributable to electrification.

Magnetic fields from steel-belted radial tires: implications for epidemiologic studies.

Magnetic fields emanate from radial tires due to the presence of reinforcing belts which are made of magnetized steel wire. When these tires spin, they generate alternating magnetic fields of extremely low frequency (ELF), usually below 20 Hz. The fundamental frequency of these fields is determined by tire rotation rate and has a sinusoidal waveform with a high harmonic content. The static field of radial tires can exceed 500 microT at the tread, and the tire-generated alternating fields can exceed 2.0 microT at seat level in the passenger compartment of vehicles. Degaussing the tires reduces both the static and alternating fields to low levels, but the fields increase gradually over time after degaussing. The tire-generated fields are below the frequencies detected by most of the magnetic field meters used in previous studies of power frequency magnetic field health effects. If these fields are biologically active, failure to detect them could compromise exposure assessments associated with epidemiologic studies.

Increased incidence of cancer in a cohort of office workers exposed to strong magnetic fields.

A small cohort of 410 office workers (263 men and 147 women, ever employed) exposed to strong magnetic fields by three 12 kV transformers located beneath their first-floor office developed eight incident cancers over a 15 year exposure period. Only one cancer was ascertained in the 254 workers employed for less than 2 years, compared to seven cancer cases ascertained in the 156 workers employed for 2 years or more (p = 0.0057; Fisher's exact test). An analysis of linear trend of cancer incidence using average years employed as an exposure score was positive (p = 0.00337) with an odds ratio of 15.1 in workers employed over 5 years. A positive trend of cancer cases with duration of employment is seen for males and females separately and together (p < 0.05). For workers employed more than 2 years, the standardized cancer incidence ratio was 389 (95% confidence interval 156-801). Cumulative magnetic field exposure may be of etiologic importance in explaining the cancer incidence pattern in this cohort.

Unusual sex ratio of births to carbon setter fathers.

In the years of 1980-1990, there were 139 birth records filed in Washington State on which father's occupation was designated as "carbon setter," a job title specific to aluminum reduction plants of the prebake type. Fifty-three (53) of these records specified sex of the birth as male, while 86 records specified sex of the infant as female. This gives a sex ratio of 0.381, which is a significant departure from the usual sex ratio at birth (proportion male = 0.512). Surveillance of sex ratio by paternal occupation is a simple method of monitoring for genotoxicity.

Quality of death certificate occupation data for a cohort of aluminum industry workers.

Occupational data from death certificates have been used extensively in health studies but their quality has been questioned. In this study, data from the death certificates of aluminum plant workers were analyzed. Aluminum industry employment was indicated in the certificate occupation/industry statement of 321 (80%) of the 403 total workers, 263 (94%) of the 280 workers who had been employed for 10 years or more, 156 (94%) of the 166 workers who died while employed, and 131 (95%) of the 138 workers who died after retirement. Of 82 certificates that did not indicate aluminum industry employment, 57 (70%) were from workers who were employed for fewer than 10 years and terminated employment for reasons other than death or retirement. This study supports the usefulness of death certificate occupational information.

Organic solvent encephalopathy: an old hazard revisited.

This report describes neurologic and respiratory symptoms among 26 engineers and contract laborers who used organic solvents and detergents to remove polychlorinated biphenyl contamination from a poorly ventilated factory basement. Neurologic symptoms included persistent central nervous system deficits; these developed in one worker after only 3 days. Respiratory symptoms included cough that persisted for more than 2 years. Laborers were more likely to report symptoms than were engineers. Appropriate ventilation or respirator use might have prevented the workers' morbidity. This incident serves as a reminder that organic solvent-related occupational illness continues to occur despite worker-health regulations and knowledge of preventive measures.

Cigarette smoking during pregnancy and mother's occupation.

The association between mother's occupation and cigarette smoking prevalence during pregnancy was analyzed in over 350,000 Washington State births during the years 1984 through 1988. Smoking prevalence during pregnancy varied markedly by maternal age, race, marital status, and social class, with higher smoking rates found in unmarried women, women 25 through 29 years old, native Americans and whites, and women in low socioeconomic classes. Women who worked in traditionally male occupations or in occupations where alcohol was served had the highest smoking rates. Occupational groups with exposure to toxic or carcinogenic substances (including second-hand smoke) also had elevated smoking rates. These data could be useful in planning intervention strategies, in studies of occupational morbidity and mortality, and in analysis of the reproductive effects of maternal occupational exposures.

Trends in teenage smoking during pregnancy. Washington State: 1984 through 1988.

Smoking rates in the United States have decreased since 1963, but this trend is less apparent in adolescents, especially girls. Using data on birth certificates from 1984 through 1988, we analyzed smoking trends during pregnancy in teenagers in Washington State. There was a small but significant increase in the overall smoking prevalence during pregnancy between 1984 (32%) and 1988 (37%). Smoking rates varied by mother's age, race and ethnicity, marital status, and prenatal care. Whites had the highest smoking prevalence, and native Americans showed the largest increase in smoking prevalence over time. In the 5 years studied, unmarried pregnant teenagers had a smoking prevalence of 42.8%, compared with a rate of 31.7% in married teenagers. Compared with other studies of smoking rates in nonpregnant teenagers, pregnant teenagers in Washington State had a much higher smoking prevalence than their nonpregnant peers, and the differences between these two groups did not appear to diminish over time. This study suggests that there is little movement toward meeting the 1990 Health Objectives for the Nation regarding smoking in Washington State teenagers who become pregnant.

Risk factors for gastroschisis.

The prevalence at birth of gastroschisis, a rare abnormality of the abdominal wall, appears to have increased over the past decade. To characterize risk factors that might explain this increase, birth certificates for Washington State residents were compared for 62 infants born with gastroschisis during the years 1984 to 1987 and 617 randomly selected unaffected infants matched for birth year. After simultaneously adjusting for 14 potential risk factors, 4 factors stood out. Infants born during January, February, or March were at greater risk than infants born in any other months (odds ratio 2.2, 95% confidence interval 1.1, 4.1). Mothers less than 25 years old were at greater risk than mothers 25 years and older, with the highest risk to mothers less than 20 years old (odds ratio 4.1, 95% confidence interval 1.4, 12.0). Women who smoked during pregnancy were at greater risk than women who did not smoke (odds ratio 2.0, 95% confidence interval 1.03, 3.8). Finally, mothers receiving inadequate prenatal care were at greater risk than mothers receiving adequate prenatal care (odds ratio 2.1, 95% confidence interval 0.99, 4.6). Unidentified behavioral and environmental exposures may explain the associations with month of birth, maternal age, and prenatal care. However, smoking during pregnancy is a plausible risk factor that should be examined further as an explanation of the apparently increasing prevalence at birth of gastroschisis in developed nations.

Altered immune status in aluminum reduction plant workers.

From 1978 to 1985, B-cell lymphoma occurred in five employees of an aluminum reduction plant (expected = 0.2; Poisson distribution). As immunodeficiency is a known risk factor for B-cell lymphoma, we did a pilot study to evaluate immune function in apparently healthy plant workers. Twenty-three volunteers were selected for study from 350 workers, representing a range of experience in the potroom and with exposures to strong magnetic fields and volatilized aromatic hydrocarbons. Potroom workers had significantly higher T8 levels (mean = 1,227) than non-potroom workers (mean = 597) (p less than .05, Wilcoxon rank sums) or established normal values (median = 450). T4 levels were higher for potroom workers (mean = 1,017) than for non-potroom workers (mean = 558) or for established norms (median = 756) (p less than .10, Wilcoxon rank sums). Ten of 20 potroom workers had abnormal T4/T8 ratios (less than 0.91) due to disproportionate elevation of the T8 subpopulation. These data suggest an underlying immune alteration in the aluminum workers studied. Further study is needed to assess the implications of abnormal T-cell subsets in a worker population with high rates of lymphoma.

Can the birth certificate yield clues to parental occupational exposures?

An analysis of reported birth record variables by parental occupation suggests that certain birth outcomes may identify toxic or carcinogenic occupational exposures of the parents. Fathers coded to an asbestos and insulation worker rubric sired fewer plural births, and more stillbirths than expected. A number of other fathers' occupations with putative exposure to asbestos and increased lung cancer mortality also showed a deficit of plural births.