After dioxin caused by slag was found in ducks from a breeding farm in Kaohsiung County’s Daliao Township (大寮鄉) recently, paddy fields in Tainan County’s Houbi Township (後壁鄉) were reported to be contaminated with chromium from slag. The government’s lack of action and poor handling of food safety has again caused a public outcry.
Tainan County’s Bureau of Environmental Protection found that the chromium content of soil on Daliao farms was more than 650 parts per million (ppm), far above the 205ppm limit set by the Department of Health.
Some independent environmental protection groups found that the chromium levels on some farmland were as high as 3,365ppm, or 13 times the legal limit, and said the total area of polluted farmland could be as large as several hundred hectares. There have also been reports that the slag site has been located on the farmland in question for three years. We must ask ourselves how much contaminated rice and vegetables has been consumed by our citizens.
Chromium is a heavy metal and small amounts of it can be found in the atmosphere, soil and water of any normal environment. For example, rainwater has 24 micrograms of chromium per liter, while soil contains 100 milligrams to 200 milligrams per liter, or between 100ppm to 200ppm.
Hexavalent chromium, or Cr(VI), is a carcinogenic type of chromium, and even small amounts of it are poisonous to humans and crops. The metabolism of plants and their functions can be impaired once exposed to Cr(VI). The human body can be directly or indirectly polluted with Cr(VI) via air, water, soil and food. When humans ingest food polluted with Cr(VI), liver and kidney functions can be damaged. Excessive amounts of chromium can cause chlorosis in plants, dry them out, reduce their production, stunt their growth and even cause them to die. In addition, chromium polluted soil or water can cause dermatitis, eczema, tracheitis and rhinitis and induce lung cancer and nasopharyngeal carcinoma in farmers who have had long-term exposure to it.
Scientists overseas found in experiments conducted on potted plants that chromium absorbed by paddy rice can transfer itself to the stems and leaves of rice and unprocessed rice. They discovered that 92 percent of the chromium found was concentrated in the stems and leaves, while 5 percent was in the husk. Because paddy rice is comparatively more susceptible to Cr(VI), it is also easier for chromium to transfer itself from stems and leaves into unprocessed rice.
The affected farmland in Tainan County contained chromium levels as high as 3,365ppm. Considerable amounts of chromium entered into unprocessed rice from the region.
At present, the Bureau of Environmental Protection in Tainan County has only removed about 500m² of the paddy that was exposed by environmental protection groups as testing positive for chromium. The paddy fields that were cleared lay quite a distance from the slag site responsible for the pollution. These actions sparked criticism from environmental groups that requested that all surrounding farmland be tested. The slow action of environmental protection authorities at the national and local levels is regrettable.
Statistics from the Environmental Protection Administration (EPA) show that, in 2005, nearly 1,600 plots of farmland nationwide were reported by local governments as exceeding soil pollution standards. This represented a total area of 378 hectares. These farmlands were mainly in Changhua and Taoyuan counties, the cities and counties of Hsinchu, Taichung and Tainan, and Kaohsiung and Yunlin counties.
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