Urinary mercury concentrations associated with dental restorations in adult women aged 16-49 years: United States, 1999-2000.

BACKGROUND: Mercury amalgam dental restorations have been used by dentists since the mid 19th century and issues on safety continue to be periodically debated within the scientific and public health communities. Previous studies have reported a positive association between urine mercury levels and the number of dental amalgams, but this relation has never been described in a nationally representative sample in the United States. AIMS AND METHODS: Using household interview, dietary interview, dental examination, and laboratory data from the 1999-2000 National Health and Nutrition Examination Survey (NHANES), the association between mercury concentrations and dental restorations was examined in US women of reproductive age. RESULTS: In women of childbearing age, approximately 13% of all posterior dental surfaces were restored with amalgams and the average urinary mercury level in women was low (1.34 microg/l). It is estimated that an increase of 1.8 microg/l in the log transformed values for mercury in urine would occur for each 10 dental surfaces restored with amalgam. CONCLUSIONS: Although the findings do not address the important issues of adverse health effects at low thresholds of mercury exposure, they do provide important reference data that should contribute significantly to the ongoing scientific and public health policy debate on the use of dental amalgams in the USA.

Half-life of polybrominated biphenyl in human sera.

Polybrominated biphenyl (PBB), a flame-retardant material, was introduced into the food chain in Michigan in 1973 due to a manufacturing and distribution mistake. Following public concern about the long-term health effects of PBB in humans, a cohort of PBB-exposed Michigan residents was assembled in 1975. We initiated this study to determine the half-life of PBB in human sera and to understand how continued body burden relates to the possible adverse health consequences of PBB exposure. To determine the half-life, eligible persons were selected from the cohort if they had at least two PBB measurements 1 year apart and had an initial level > or = 20 pbb. There were 163 persons who met the criteria with a median PBB level of 45.5 ppb. The estimated half-life is 10.8 years (95% CI, 9.2-14.7 years). The body burden of PBB in exposed persons will decrease only gradually over time. For persons with an initial level of 45.5 ppb of PBB, it will take more than 60 years for their PBB levels to fall below the current level of detection of 1 ppb.

Paternal occupation and Wilms' tumour in offspring.

A case-control study was conducted to test the hypothesis that paternal occupation is a risk factor for Wilms' tumour in offspring. Occupations associated with exposure to lead (Pb) and to hydrocarbons were examined by computing odds ratios, all of which were greater than unity but not by a statistically significant margin. When painters were considered separately, children whose fathers had been so employed were six times more likely to develop Wilms' tumour than children whose fathers had other occupations. Like the results for the Pb and hydrocarbon related occupations, the estimated relative risk associated with painters did not reach statistical significance. Although these data require cautious interpretation because of the relatively small number of subjects, the results reported here are not wholly consistent with the results of the one previous study of paternal occupation and Wilms' tumour in offspring.

Etiology of melanoma.

Although the precise etiology of melanoma remains unknown, much data link sunlight to melanoma. The imperfect evidence associating sun exposure (particularly UVB radiation) with melanoma emerges from human data, obviating problems inherent in extrapolation from animal and other models. However, the mechanism by which sunlight might possibly initiate or promote melanoma remains obscure. Some clarification should emerge from the potential isolation of genes that carry susceptibility to melanoma in families prone to the disease; such work could serve as a basis to distinguish genetic and environmental influences in melanoma [167]. Continued studies of faulty DNA repair in XP patients may elucidate the steps in mutagenesis and carcinogenesis. Future case-control studies must address the limits on the accuracy of recall and the limits on statistical methods to separate the cluster of phenotypic risk needed in determining biologically effective dose. Animal and in vitro studies must contribute more insight. Further research in the South American opossum models appears promising [72]. Although ozone depletion has been documented, there has been little definitive evidence of subsequent increase of UVB at the Earth's surface. Nevertheless, the threat posed by ozone depletion deserves continued environmental action and public education. The role of precursor lesions, particularly dysplastic nevi/atypical moles, must be clarified with future research. The distribution of melanoma among various work forces suggests that occupational risk factors may play an important role in the etiology of this disease [168-170]. The consistent reports of excess melanoma among accountants, clerical workers, professional workers, and teachers deserve further study. Furthermore, evidence of excesses in printing and press, petrochemical, and the telecommunications industries require follow-up. Carefully planned studies that account for nonoccupational risk factors are recommended. Research over the last four decades has brought much information about melanoma etiology. More work is needed to learn the precise cause and ultimately to prevent avoidable mortality from malignant melanoma.

Cardiovascular mortality--the hidden peril of heat waves.

OBJECTIVE: Define the mortality associated with extremely hot weather during the 04 July through 14 July, 1993 heat wave that struck the northeastern United States. METHODS: DESIGN--A rapid field assessment was used to compare mortality occurring during the heat wave to mortality occurring during a period in which there was no heat wave using copies of death certificates. The findings of the rapid field assessment were validated, and it was determined whether increases in mortality occurred in other metropolitan east-coast counties also affected by the heat wave, by reviewing computerized mortality files. SETTING--Information was collected on all deaths occurring in Baltimore City, Maryland; Baltimore County, Maryland; Essex County, New Jersey; Newcastle County, Delaware; and Philadelphia County, Pennsylvania; during these specified study periods: 08-18 June (comparison period) and 06-16 July (heat wave study period), 1993. MAIN OUTCOME MEASURES--Ratios for total mortality, cause-specific mortality, and variables such as age, sex, race, residence, and day and place of death, that were available from death certificates were calculated. RESULTS: From the rapid field assessment, the following were observed: a 26% increase in total mortality and a 98% increase in cardiovascular mortality associated with the heat wave in Philadelphia. Data from the computerized mortality files showed an increase in total mortality in four of five counties examined and an increase in cardiovascular mortality in all five counties. The risk for death for those dying from cardiovascular disease increased significantly for people older than 64 years, for both sexes, and all races. CONCLUSION: As initially indicated by the Philadelphia Medical Examiner, there was excess mortality associated with a heat wave in Philadelphia. All other nearby counties examined also experienced excess mortality associated with the heat wave, although this excess was not recognized by the local health officials. The true impact of a heat wave that causes excess preventable mortality must be appropriately and rapidly ascertained. Using a national standard to certify a death as heat-related will provide the needed information rapidly so that public health resources can be more effectively allocated and mobilized to prevent further heat-related illnesses and death.

Occupational exposures among fathers of children with Wilms' tumor.

An occupation-and-exposure linkage system was utilized to perform an epidemiologic case-control study of paternal occupation and Wilms' tumor in offspring. The first part of the study was designed to test the hypothesis that paternal lead (Pb) exposure is a risk factor for Wilms' tumor in offspring. The second part of the study was an exploratory analysis that sought to generate possible etiologic hypotheses about other paternal exposures in the workplace in relation to Wilms' tumor. Calculation of odds ratios indicated that there was no statistical difference in the frequency of occupational exposure to Pb, Pb alkyls, and Pb salts for fathers of children with Wilms' tumor and fathers of controls, a finding that contrasts sharply with the results of the one previously reported study in this area. In the exploratory phase of the study, case fathers were found more likely to have been exposed to boron, while control fathers were found more likely to have encountered insecticides, acetylene, o-chlorobenzylidene, oil orange ss, and diethylene glycol; the differences were statistically significant. Troublesome methodologic problems, including exposure misclassification, sample size, and multiple comparisons, are discussed.

Parental occupation and intracranial neoplasms of childhood: anecdotal evidence from a unique occupational cancer cluster.

Near the end of the data-collection phase of a case-control interview study of environmental factors and childhood brain tumors, an unusual space-time cluster was revealed. Not only had six genetically unrelated children been diagnosed with a primary intracranial tumor in a recent 2.4 year period in a rural county in Ohio, but each child had one parent employed by the same company (two mothers, four fathers). This represents an observed/expected ratio greater than 70 (p much less than 0.001). All tumors were microscopically confirmed, and all case parents worked at the facility in question for at least 1 year prior to conception, during the index pregnancy, and for at least 6 months after birth. The place of parental employment was an electronics firm (Standard Industrial Classification [SIC] group number 367, electronic components and accessories), where more than 100 chemical compounds are used by the company in a manufacturing process. Results of the cluster investigation are described, including a description of the case series. This cancer cluster is unique in that the index case series is composed of the offspring of workers, not the workers themselves.

An outbreak of hypervitaminosis D associated with the overfortification of milk from a home-delivery dairy.

OBJECTIVES: The purpose of the study was to identify cases of hypervitaminosis D caused by the inadvertent overfortification of milk from a home-delivery dairy and to identify risk factors for this illness. METHODS: Hospital discharge, laboratory, and state health department data were used to define, identify, and describe cases of hypervitaminosis D diagnosed in the exposed communities between January 1, 1985, and June 30, 1991. To identify disease risk factors, community-based sex- and age-matched controls were used in a case-control study. RESULTS: Of the 56 case patients identified, at least 41 were hospitalized; 2 died. The study included 33 case patients and 93 control subjects. Nineteen of the 33 case patients had been customers of the implicated dairy. Risk of illness rose with increasing consumption of the dairy's milk and was also associated with vitamin D supplement use, sunburn susceptibility, and cancer history. Accounting for these factors did not alter the association between drinking the dairy's milk and developing hypervitaminosis D. CONCLUSIONS: Overfortification of milk with vitamin D can lead to hypervitaminosis D, manifested by severe illness and death. The episode highlights the need for monitoring the fortification process and enforcing the upper limit for vitamin D addition to milk.

Surveillance of occupational skin diseases: a method utilizing workers' compensation claims.

In order to determine the feasibility of using workers' compensation claims (WCC) for surveillance of occupational skin diseases, we reviewed all WCC received in the state of Ohio from 1980 through 1984. A total of 4,214 WCC for occupational skin diseases were filed by 2,610 Ohio companies, of which 1,656 (63%) companies were classified in Standard Industrial Classification (SIC) categories with average annual WCC rates above the overall state average for skin diseases. During the five year study period, 102 companies filed six or more WCC, of which 85 (83.3%) companies were classified in SICs with above-average WCC rates. WCC from 65 (63.7%) of these 102 companies implicated either the same occupation or causal agent in 50% or more of WCC received from each respective company. Using SIC classifications with WCC rates above the state average and six or more filed WCC as measures of risk, there was good correlation between company risk ranking by SIC categorization and number of WCC filed. This study suggests that active intervention strategies to prevent occupational skin diseases can be based on primary identification of companies filing WCC, followed by secondary identification of high-risk occupations or causal agent exposures within these companies.