Project 7:

Arsenic and Health in Taiwan and Bangladesh

Project leader: David C. Christiani
Project co-leader: Yue-Liang Leon Guo

Background:

Studies have confirmed that arsenic is a carcinogen at high doses. Arsenic can cause non-melanoma skin cancers (such as squamous-cell carcinoma), as well as bladder, lung, and other internal cancers. In addition, arsenic affects bone marrow, skin, the peripheral nervous system and the vascular system. Populations can be exposed to arsenic by inhaling contaminated dust from nearby waste sites, and by drinking contaminated water.

Specific aim:

This project will provide data about the health risks associated with arsenic exposure for a range of exposure levels from low to high. Through this project we will learn what human tissues, such as toenails, are the best indicators of arsenic exposure.

Methods:

We conducted this project in Taiwan. The Bangladesh portion of the project is still underway. In Taiwan, the exposures studied were similar to the low level exposures at U.S. Superfund sites. In Bangladesh, the arsenic exposure levels in drinking water are very high.

One study will be of the human response to exposure. This study will follow 100 families (50 in Taiwan and 50 in Bangladesh), including 40 children (20 in Taiwan and 20 and Bangladesh). We will take samples of drinking water, toenails and urine several times over the course of one year. The samples will be tested so that researchers can determine the relationships between arsenic exposure in water and diet and the use of toenails and urine.

In the second phase of this study we enrolled individuals diagnosed with bladder cancer, squamous cell carcinoma or non-squamous cell carcinoma skin lesions, as well as individuals from the same populations who do not suffer from these illnesses.

We collected information from the participants about their exposure, including potential exposures through their work, diet, smoking, lifestyle, sun exposure, and drinking water. Participants submitted toenail and urine samples as well as drinking water samples to be tested. We analyzed toenail and urine samples for arsenic and compared those data with the survey data to see if the results for those with the cancer are different from those without cancer.

Results:

• Arsenic levels in nails and drinking water are similar predictors of the risk of skin lesions. Toenail samples can reliably estimate arsenic exposures and predict the risk of skin lesions.
• Antimony, often found along with arsenic in drinking water, is not likely to complicate or worsen the relationship between well-water arsenic exposure and potential health outcomes when present in the geochemical environment.
• Chewing betel nuts (seeds of the betel palm which is native to the area), is associated with increased risk of skin lesions.

Recent publications:

• McCarty, K. M., D.B. Senn, M.L. Kile, Q. Quamruzzaman, M. Rahman, G. Mahiuddin,and D.C. Christiani. 2004. Absence of significant antimony in Bangladesh tube well water. Environ. Health Perspect. 112:809-11.