Recent Developments

1. Selenium and Human Health - Summary
2. Selenium and Human Health - Latest Studies
3. Selenium in Food: Studies on Grains and Fish
4. Studies on Selenium in China

 

4. SELENIUM & CHINA STUDIES

1. Appleton, J.D., et al., " Selenium in soil, grain, human hair and drinking water in relation to esophageal cancer in the Cixian area, Hebei Province, People's Republic of China", Applied Geochemistry, Volume 21(4), April 2006.

Selenium deficiency was suspected to be a factor in the etiology of esophageal cancer in Linxian and Cixian regions of China. Mortality was reduced with vitamin supplements (Vitamin E, selenium , b-carotene). To evaluate the role of selenium , the distribution of total selenium in cultivated top soils, grain, human hair and drinking water was studied in 15 villages in 1980-1990s. The study demonstrated that total selenium concentrations in drinking water, soil, grain, and hair increase from the low esophageal cancer area to the high cancer area, contrary to the expected trend. Nitrate in the drinking water is much higher in the area with high cancer mortality rate. In addition, mycotoxins, nitrosamine precursors in grain, and vitamin supplements are potential factors which need further evaluation. Therefore, selenium levels in the diet and biological samples were higher for populations with lower esophageal cancer rates, contrary to expected results.

2. Yang, J., et al., "Keshan disease surveillance in Xunyi County of Shaanxi Province in 2005", Chinese Journal of Endemiology, Volume 25(6), 2006.

Clinical examinations and electrocardiography were performed for residents to observe the incidence and transition of acute, subacute and chronic Keshan disease, a potentially fatal disease of the heart muscle caused by selenium deficiency . The content of selenium in grain and hair was determined. Results indicate no acute and subacute Keshan disease in the surveillance areas. The prevalence of latent and chronic Keshan disease was 3.79% and 0.35%, respectively. The rate of abnormal electrocardiogram was 11.4%. The content of selenium in hair was 0.579 mg/kg and in grain was 0.089 mg/kg. The background incidence rate of natural chronic Keshan disease is about 3/10 000, or 0.03% in Shaanxi Province versus the rate in Xunyi County of 0.35%, or about ten times higher in Xunyi County versus the background incidence rate in Shaanxi Province.

3. Li, Q., Zhao, Z.H., "Prevalence state of Kashin-Beck disease in Qinghai Province: A retrospective analysis", Chinese Journal of Endemiology, Volume 25(6), November 2006.

In three regions of Qinghai Province, the prevalence of Kashin-Beck Disease (KBD) from 1982 through 2005 was investigated. According to National Survey Scheme on KBD, clinical examination and X-ray photography were performed in local children (7-12 years). Selenium content in hair, food and soil were also detected. The prevalence state is active and serious in Xinghai and Guide regions; however it decreased naturally in Banma KBD region from 1984 to 2005. Selenium testing identified an increase in body levels and in the environment over time. Consuming locally produced grains and unscientific reaping and storage of grain are possible two main factors affecting KBD.

4. Finkelman, R.B., et al., "Health impacts of domestic coal use in China", Proceedings of the National Academy of Sciences of the United States of America, Volume 96(7), March 1999.

Domestic coal combustion has had profound adverse effects on the health of millions of people worldwide. In China alone several hundred million people commonly burn raw coal in unvented stoves that permeate their homes with high levels of toxic metals and organic compounds. At least 3,000 people in Guizhou Province in southwest China are suffering from severe arsenic poisoning. The primary source of the arsenic appears to be consumption of the chili peppers dried over fires fueled with high arsenic coal (up to 35,000 ppm arsenic). The chili peppers adsorb 500 ppm arsenic on average. Excess fluorine in coal has caused more than 10 million people in Guizhou Province to suffer from dental and skeletal fluorosis. Polycyclic aromatic hydrocarbons formed during coal combustion are believed to cause or contribute to the high incidence of esophageal and lung cancers in parts of China. Domestic coal combustion also has caused selenium poisoning and possibly mercury poisoning.

5. Spencer, J., "Toxic Factories Take Toll on China's Labor Force", Wall Street Journal, January 15, 2008.

Over the holidays, millions of American children received Chinese-made toys powered by cadmium batteries. Cadmium batteries are safe to use, are cheap, saving parents about $1.50 on the average toy, compared with pricier batteries. But, cadmium batteries can be hazardous to make. In southern China, Wang Fengping worked in and regularly inhaled the red cadmium dust that filled the air in the plant. Now at 45, Ms Wang is often too weak to walk. Her kidneys have failed and her doctors have identified cadmium poisoning as the culprit. About 400 other workers have been found to harbor unsafe levels of cadmium, which can cause kidney failure, lung cancer and bone diseases.

Today, only two USA companies still make cadmium batteries, and they specialize in high-end batteries for use in equipment such as aircraft engines. USA laws require them to follow strict guidelines on worker safety and environmental protection. In China, government standards on cadmium exposure are in line with those endorsed by the World Health Organization. And there are safe cadmium plants in China.

But having rules and enforcing them are two different things. China has dozens of "hot spots" where the cadmium contamination is similar to levels at USA superfund sites. More than 10% of China's arable land is contaminated with heavy metals such as cadmium and other heavy metals such as arsenic, lead, mercury, and selenium , according to the State Environmental Protection Agency. And, the metals are entering China's food supply. At least a dozen academic studies in the past two years have found unsafe levels of cadmium in fruit and vegetables grown in Chinese soil. Last year researchers at the Guangdong Institute of Ecology found excessive levels of cadmium in Chinese cabbage grown in Foshan. Last year, at least 20 workers at a cadmium battery plant in Wuxi were found to have elevated levels of the toxin, and two were diagnosed as poisoned. In 2005, 1,000 workers at Huanyu Power Source Co., in Xinxiang, Henan, were also found with cadmium exposure.

 

< BACK. . . . .. .. .. . . .. .Index........................