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Meei-Maan Wu,¹ Hung-Yi Chiou,² Tsung-Wei Wang,¹ Yu-Mei Hsueh,² Iuan-Horng Wang,³ Chien-Jen Chen,³
and Te-Chang Lee¹

¹Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, Republic of China; ²Department of Public Health, Taipei Medical College, Taipei, Taiwan, Republic of China; ³Graduate Institute of Epidemiology, National Taiwan University, Taipei, Taiwan, Republic of China

Abstract

Arsenic is a notorious environmental toxicant known as both a carcinogen and an atherogen in human beings, but the pathogenic mechanisms are not completely understood. In cell culture studies, trivalent arsenic enhanced oxidative stress in a variety of mammalian cells, and this association may be closely associated with the development of arsenic-related diseases. To investigate the effect of arsenic exposure on oxidative stress in humans, we conducted a population study to determine the relationships of blood arsenic to reactive oxidants and antioxidant capacity at the individual level. We recruited 64 study subjects ages 42-75 years from residents of the Lanyang Basin on the northeast coast of Taiwan, where arsenic content in well water varies from 0 to >= 3,000 µg/L. We used a chemiluminescence method, with lucigenin as an amplifier for measuring superoxide, to measure the plasma level of reactive oxidants. We used the azino-diethyl-benzthiazoline sulphate method to determine the antioxidant capacity level in plasma of each study subject. We determined arsenic concentration in whole blood by hydride formation with an atomic absorption spectrophotometer. The average arsenic concentration in whole blood of study subjects was 9.60 ± 9.96 µg/L (± SD) with a range from 0 to 46.50 µg/L. The level of arsenic concentration in whole blood of study subjects showed a positive association with the level of reactive oxidants in plasma (r = +0.41, p = 0.001) and an inverse relationship with the level of plasma antioxidant capacity (r = -0.30, p = 0.014) . However, we found no significant association (p = 0.266) between levels of plasma reactive oxidants and antioxidant capacity. Our results also show that the lower the primary arsenic methylation capability, the lower the level of plasma antioxidant capacity (p = 0.029) . These results suggest that ingestion of arsenic-contaminated well water may cause deleterious effects by increasing the level of reactive oxidants and decreasing the level of antioxidant capacity in plasma of individuals. Persistent oxidative stress in peripheral blood may be a mechanism underlying the carcinogenesis and atherosclerosis induced by long-term arsenic exposure. Key words: antioxidant capacity, azino-diethyl-benzthiazoline sulfate method, blood arsenic, chemiluminescence, population study, reactive oxidants, superoxide. Environ Health Perspect 109:1011-1017 (2001) . [Online 26 September 2001]

http://ehpnet1.niehs.nih.gov/docs/2001/109p1011-1017wu/ abstract.html

Address correspondence to T-C Lee, Institute of Biomedical Sciences, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan, Republic of China. Telephone: 8862-26523055. Fax: 8862-27829142. E-mail: bmtcl@ibms.sinica.edu.tw

We thank D. Platt for carefully reading this manuscript.

This work was supported by grants from the Clinical Research Center, Institute of Biomedical Sciences, Academia Sinica (IBMS-CRC88-T05 and IBMS-CRC89-T01) , and from the National Science Council (NSC-85-2331-B-002-265, NSC-86-2314-B-002-336, NSC-87-2314-B-002-044, and NSC-88-2314-B-002-005) , Republic of China.

Received 27 November 2000 ; accepted 21 March 2001.