傳統上,訂定灌溉用水水質標準時,是考量維護作物之健康安全。但重金屬是累積性的毒物,會藉由農地作物而進入食物鏈,危害人體健康。本研究以人類的健康為出發點來考量,以人類健康風險評估現有的標準並提出一些建議。因此假設了三種暴露情境:一般大眾、污染區居民、污染區農夫,並作一個案例分析。結果顯示,這三種暴露情境下,水質標準的項目有超過可接受的風險,所以有必要檢討水質的標準。而且在污染區的灌溉用水應該要另外規範。而案例分析的結果顯示,在符合政府各權責主管機關訂定的各種標準下,亦有可能對人體健康造成超過風險的影響。而上述推論結果與衛生署在彰化縣的人體血液、尿液調查結果相比趨勢吻合。本研究建議政府機關各單位在制訂各類標準時,宜考量人類健康風險評估之觀念,使法規標準之間更為相容。
Traditionally, the irrigation water quality standard was established for the health and safety of crops. However, heavy metals may accumulate in the farmland then enter the food chain by the absorption of the crop and cause harm to human health. This study evaluates the current irrigation water quality standard in the view point of human health risk assessment. There are three hypothetical exposure scenarios in the study and a case study is analyzed. The three exposure scenarios are resident, resident in contaminated region, farmer in contaminated region, respectively. The result shows that As has exceed the acceptable risk in all three exposure scenarios, therefore the irrigation water quality standard must be reviewed and the standard of the As should be more strictly. The case study results coincided with the blood and urine test in Chang-Hwa area which suggests that human health risk assessment should be considered as to establish all kinds of standards.