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Final Progress Reports: Harvard School of Public Health: Arsenic Exposure and Skin and Bladder Cancers

Superfund Research Program

Arsenic Exposure and Skin and Bladder Cancers

Project Leader: David J. Hunter
Grant Number: P42ES005947
Funding Period: 1995 - 2000

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Final Progress Reports

Year:   1999 

During the past year, work has focused on studying arsenic carcinogenesis in two populations; one in Taiwan, an area of known high arsenic exposure in the past few decades, and the other in the U.S. where levels of exposure to arsenic are relatively low.

To assess the effect of arsenic exposure and solar radiation on the development of non-melanoma skin cancer, a matched case-control study was undertaken in the southwestern part of Taiwan, the area where blackfoot disease (BFD) was first reported. From Jan 1, 1996 to Dec 31, 1998, 260 histologically confirmed non-melanoma skin cancer (NMSC) cases were recruited, and 212 hospital controls were identified consisting of patients seen in the outpatient clinic on the same day. Controls were patients with a diagnosis of upper respiratory infection, and were matched to cases by age and gender. Information on history of consuming well water, duration of living in the BFD-area, skin complexion, skin reaction after sun exposure, lifetime sunlight exposure, smoking, alcohol consumption, and regular use of hair-dye, paints, and pesticides were obtained through personal interviews. The results suggest that history of living in the BFD-area was associated with NMSC, and skin cancer was associated with high levels of arsenic exposure. People with higher levels of cumulative sun exposure were at increased risk of NMSC. In summary, both cumulative arsenic and sunlight exposure are important in accounting for the individual risk of non-melanoma skin cancer in this Chinese population, whereas constitutional factors, skin reaction to sunlight, and life-style habits are not related to skin cancer.

In the second part of Taiwan study, researchers conducted a case-control study to examine the association between cumulative arsenic exposure and bladder cancer. Two hundred bladder cancer patients (cases) and 400 cataract patients (controls) matched on age and gender were recruited from Jan 1, 1995 to Dec 31, 1999. Arsenic methylation ability and nutritional status may modify the association between arsenic exposure and the risk of bladder cancer. The first void spot urine was collected from each subject, and HPLC-ICP-MS was used to speciate the four arsenic species (arsenite, As (III); arsenate, As(V); monomethylarsonate, MMA; dimethylarsine, DMA) in urine samples. Information on nutritional status, history of residence, lifestyle, and other risk factors were collected by a questionnaire. The analyses of arsenic metabolites are underway. The results of multiple logistic regression models that explore the association between cumulative arsenic exposure and bladder cancers will be available in the year 2000.

For the study in the U.S. population, a nested case-control study of squamous cell carcinoma (SCC) of the skin within Nurses' Health Study (NHS) cohort was conducted. Toenail arsenic concentration, previously shown to reflect intake of arsenic from drinking water, was used as an indicator of environmental exposure to arsenic. Toenail samples were collected from 62,641 women in 1982, prior to the diagnosis of SCC. During the study period 1984-1992, 250 incident cases of histologically confirmed SCC were selected; one control was randomly selected matched by age and year and month of toenail return to each case. The median toenail arsenic concentrations were similar in cases and controls. There was no evidence of a positive association between toenail arsenic level and risk of SCC. Project investigators did not observe any relationship between arsenic levels experienced by women in the general US population and the risk of SCC of the skin.

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