The effects of risk awareness and management on the risk of farmers due to arsenic contamination and on the cost of site management.

臺北市政府環境保護局調查研究北投關渡平原發現，達63公頃之土地土壤中重金屬砷濃度超過土壤污染管制標準，範圍包括大度路以北、大業路以西以及新貴子坑溪以東之處。此污染現象經研判係早期引用含砷之溫泉水灌溉，致砷累積於農田土壤所致。 目前此區域仍種植許多農產品，例如水稻、蔬菜等食用作物。重金屬砷會為植物所吸收而累積於植體內，使含有重金屬之農作物，經由食物鏈影響農民食之安全。本研究之目的係欲瞭解該區農民對蔬菜的攝食行為、環境風險認知等狀況，藉以修正預設參數值，估算其每日之砷暴露量以做為健康風險評估之依據；並分析風險教育與風險管理對於降低風險之成本與效益。 本研究對象為在北投區豐年段一小段地號，從事農作之高暴露族群之農民(n=22)。調查結果顯示，農民因其多自耕自食，經食物鏈攝取比例較高，其平均之總致癌及總非致癌風險（n=22 之平均值）分別為5.65*10-4 及3.16。計算個人健康風險之總致癌及總非致癌風險亦皆超過行政院環境保護署初步評估辦法所界定之可接受範圍(>1＊10-6、1＊100)。 農民對於食用蔬菜之風險，不認為該區土壤砷含量經攝食進入人體後會有負面影響。利用改變農民活動型態進行風險管理，可以經濟有效降低農民砷暴露之健康風險。但是風險之溝通與教育，尚須藉官方強而有力之理由與說法，使原農作行為得以改變。本研究顯示風險評估是一種工具，可藉此針對高污染受體進行必要之管控，以最低成本降低民眾最多之風險。Sixty three hectares of land located north of Dadu Road, west of Daye Road and east of New Kweizhiken Creek has been found polluted by arsenic according to the research report by the Environmental Protection Bureau of Taipei City Government. The contaminant is believed coming from the irrigation water drawn from arsenic-containing spring water and being accumulated in the soil of farmlands. Rice and various vegetables are still being planted in this area currently. Arsenic in the soil may pose undesirable health effects to the farmers and other people who consume the agricultural products in which the arsenic is accumulated through absorption from the soil. The purpose of this study were to investigate the farmers’dietary patterns, perception of the possible risk, and the possible change of behavior after the acknowledging of the potential risk; and to establish some site-specific parameters in the calculation of exposure, assess the health risk of farmers before and after the risk acknowledgement. The reduction of health risk and the cost of some risk education or risk management strategies were compared. Total 22 farmers residing in the area specified as Fong-nen Section #1, Beitou District, who is supposed to be under highest risk due to soil pollution, were interviewed. Potential risks of individuals were estimated with some exposure factors derived from the results of the field survey. Major portion of the potential risk comes from the uptake of vegetables grown on the site. The average lifetime cancer risk is 5.64 x 10-4 and the non-cancer hazard quotient is 3.16, which all exceed the acceptable risk suggested by the Environmental Protection Administration (ROC) as a criterion of being classified as a remediation site. The results of interviewing indicate that farmers will not change their dietary habits even they have been notified the health risk of consuming the vegetables through media and personal communication. The results also indicate that higher intensity of education and persuasion given by the governmental authorities should be able to change their dietary and farming behaviors and reduce their health risk. With the application of risk assessment as a tool the results of this study enable us to evaluate the benefits (e. g., reduction of risk) and cost of several strategies and formulate the best controlling measure to achieve the goal of managing the risk posed by arsenic-contaminated soil