不同水稻品种无机汞和甲基汞富集及暴露风险评估

Inorganic mercury and methylmercury bioaccumulation in different rice species and exposure risk assessment

最近研究表明水稻食用成为内陆汞矿区人体的另一个主要甲基汞暴露途径。水稻是一种高甲基汞富集的植物,而在所有的汞化合物中,甲基汞的毒性最强,能通过食物链富集放大。因此水稻中甲基汞富集对人体的危害引起了广泛的注意。本论文主要通过模拟汞污染地区水稻生长实验,来探究无机汞和甲基汞在水稻体内富集的机制,并对水稻富集无机汞和甲基汞的相关因素进行推测,对汞污染地区的水稻种植做出指导。同时通过分析居民平均每日可能通过水稻摄取的甲基汞量对当地居民的甲基汞暴露风险进行评价。本研究发现稻米是水稻富集甲基汞的主要部位。水稻体内的无机汞主要来源于空气而不是土壤。水稻成熟后,水稻各组织中大部分的甲基汞转运到水稻稻米中,而水稻中大部分无机汞则不参与转运。实验的四种水稻品种富集甲基汞的能力有所不同,富集甲基汞能力为有色稻种>粳米>籼米。稻米富集甲基汞量与稻米中的氨基酸含量有一定相关性。同时根据四种水稻可能对居民的每日甲基汞暴露值分析发现其中两种水稻的甲基汞暴露健康风险指数大于1,当地居民长期食用将面临着较高的甲基汞暴露风险。

Recent studies have shown that rice consumption can be the major pathway of methylmercury(MeHg)exposure in inland Hg mining areas.Rice is a high bioaccumulation plant for MeHg,and MeHg is most toxic in all mercury form and could biomagnify through the food chain.Therefore,the accumulation of MeHg in rice could pose health threaten to human.Inorganic mercury and MeHg bioaccumulation mechanism in each rice tissue of different rice species was explored through the experimental simulation of rice growth in mercury pollution area,and the related factors of rice bioaccumulation of inorganic mercury and MeHg.At the same time through the analysis of residents MeHg probable daily intakes from rice to evaluate MeHgexposure risk to residents.This study found that grain was the main parts to bioaccumulate MeHg in rice plants.Inorganic mercury of rice plants mainly came from air rather than soil.Most of MeHg in rice plants was transferred to grain during ripening period,while most of inorganic mercury of rice plants did not transfer to the grain.The MeHg bioaccumulation of four rice species was different,and the bioaccumulation ability of methyl mercury was colored rice >japonica rice>long rice.Methylmercuy bioaccumulation of rice correlated with the amino acid contents in rice plants.And through the probable daily intakes risk assessment,the Health Risk Index(HRI)of two rice species were more than 1,and the local residents were exposed to the MeHg through the rice consumption in the long-term.