Arsenic ingestion from well water associated with increased risk of lung cancer

[Cary Renquist <cary_rdsfe@pacbell.net>]

So, is there any correlation between arsenic levels 

and radon levels in the environment?



C.



************************************



<http://www.eurekalert.org/pub_releases/2004-12/jaaj-aif121604.php>



Residents of Taiwan who consumed drinking water with

high levels of arsenic have a higher risk of lung

cancer, with cigarette smokers from this group having

an even greater risk, according to a study in the

December 22/29 issue of JAMA. 



Arsenic is a naturally occurring element in soil, and

can contaminate drinking water, according to

background information in the article. Residents of

the southwestern and northeastern coasts of Taiwan had

been drinking well water contaminated with a high

concentration of arsenic before the establishment of

the public tap water system. 



Chi-Ling Chen, Ph.D., of the College of Public Health,

National Taiwan University, Taipei, Taiwan, and

colleagues conducted a study to determine the

dose-response relationship between ingested arsenic

and lung cancer risk and the added effect of cigarette

smoking on this risk. 



The study included 2,503 residents in southwestern and

8,088 in northeastern arsenic-endemic areas in Taiwan,

who were followed up for an average period of 8 years.

Information on arsenic exposure, cigarette smoking,

and other risk factors was collected at enrollment

through standardized questionnaire interview. 



During the study followup period, there were 139 newly

diagnosed cases of lung cancer. Residents with the

highest level of arsenic exposure had a 3.29 times

increased risk for lung cancer, after adjusting for

various factors including age, sex, and cigarette

smoking status at recruitment. Among nonsmokers, those

who were exposed to the highest arsenic level had

about twice the risk for lung cancer when compared

with those with the lowest level of exposure. Among

participants with the lowest arsenic level, those who

had the highest cumulative cigarette smoking exposure

had a 4-fold risk of lung cancer compared with

nonsmokers. When compared with nonsmokers with the

lowest levels of arsenic exposure, those who consumed

well water with the highest arsenic levels and smoked

for more than 25 pack-years had a more than 11-fold

risk of lung cancer. 



"Approximately 32 percent to 55 percent of lung cancer

cases were estimated to be attributable to the

combined effect of cigarette smoking and ingested

arsenic, depending on the levels of both exposures,"

the authors write. "The synergy indices ranged from

1.62 to 2.52, indicating a synergistic effect of

ingested arsenic and cigarette smoking on lung

cancer." 



"The reductions in cigarette smoking would likely

reduce the lung cancer risk accompanied by exposure to

arsenic, and similarly, reductions in arsenic exposure

would reduce the lung cancer risk among cigarette

smokers. Appropriate public health interventions, such

as cigarette smoking cessation programs and reduction

in arsenic concentration of drinking water, are

warranted. Furthermore, it is essential to take

cigarette smoking into consideration in the risk

assessment and the determination of the maximal

contamination level of arsenic in drinking water," the

authors conclude.



(JAMA. 2004; 292: 2984-2990. Available post-embargo at

www.jama.com) 



###



Editor's Note: This study was supported by grants from

the National Science Council and from the Department

of Health, Executive Yuan, Taiwan. 



Editorial: Lung Cancer Etiology - Independent and

Joint Effects of Genetics, Tobacco, and Arsenic 



In an accompanying editorial, Habibul Ahsan, M.D.,

M.Med.Sc., of Columbia University, New York, N.Y., and

Duncan C. Thomas, Ph.D., of the University of Southern

California, Los Angeles, comment on the two lung

cancer studies in this week's JAMA. 



"Irrespective of the roles of familial aggregation and

environmental exposures to arsenic or other

carcinogens, lung cancer is primarily caused by

tobacco smoking--an exposure that is largely

preventable. If nicotine addiction genes or modifier

genes play roles in subsets of patients with lung

cancer, such cases can be prevented by preventing

tobacco smoking. Although there are no addiction genes

for arsenic or other environmental exposures, modifier

genes could modulate the effects of these nontobacco

carcinogens. Such genes, in combination with major

genes, could lead to familial aggregation." 



"Innovative epidemiological studies to detect and

separate these effects, taking the lead from studies

like those of Jonsson et al and Chen et al, need to be

designed in the future. Even for individuals with such

a familial risk, or for those who are already

chronically exposed to arsenic or other lung

carcinogens, avoiding tobacco smoking remains the most

feasible option for reducing lung cancer risk," they

write.



(JAMA. 2004; 292: 3026-3029. Available post-embargo at

www.jama.com)



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