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Abstract: Quantitative analysis for the risk of human cancer from the ingestion
of inorganic arsenic has been based on the reported cancer mortality experience
in the blackfoot disease (BFD) -endemic area of southwest Taiwan. Linear
regression analysis shows that arsenic as the sole etiologic factor accounts
for only 21% of the variance in the village standardized mortality ratios for
bladder and lung cancer. A previous study had reported the influence of
confounders (township, BFD prevalence, and artesian well dependency)
qualitatively, but they have not been introduced into a quantitative
assessment. In this six-township study, only three townships (2, 4, and 6)
showed a significant positive dose-response relationship with arsenic exposure.
The other three townships (0, 3, and 5) demonstrated significant bladder and
lung cancer risks that were independent of arsenic exposure. The data for
bladder and lung cancer mortality for townships 2, 4, and 6 fit an inverse
linear regression model (p < 0.001) with an estimated threshold at 151 microg/L
(95% confidence interval, 42 to 229 microg/L) . Such a model is consistent with
epidemiologic and toxicologic literature for bladder cancer. Exploration of the
southwest Taiwan cancer mortality data set has clarified the dose-response
relationship with arsenic exposure by separating out township as a confounding
factor.


Sources: arsenic-crisis group

Posted by: sol
Date : 18th July 2006