我国人群高氯酸盐暴露途径及贡献率分析

Analysis of exposure routes and contribution rate of perchlorate in China

由于高氯酸盐干扰甲状腺对碘的吸收,抑制人体甲状腺激素的分泌而导致碘缺乏症,近年来引起了环境学家和卫生部门的广泛关注.为研究高氯酸盐在我国人群中多途径暴露情况,通过对"十一五"和"十二五"期间全国重点城市饮用水水质监测数据统计,结合中国居民膳食摄入量,计算出全国14个城市居民在摄入、呼吸、皮肤接触3种暴露途径下高氯酸盐的贡献率,并分析不同流域地区高氯酸盐贡献率的差异.结果显示:(1)我国自来水中高氯酸盐浓度在0.149~152μg/L之间.各省份污染水平存在显著差异,武汉、上海、成都污染最为严重.(2)呼吸和皮肤接触途径下高氯酸盐的贡献率很小,分别为0.88%和0.27%,主要为经口摄入途径,其中饮用水、谷物、蔬菜约占总摄入量的92%,具体为蔬菜(32.05%)>饮用水(32.02%)>谷物(28.12%)>肉类(2.51%)>水果(2.30%)>薯类(1.85%)>乳类(1.31%)>蛋类(0.87%)>水产品(0.86%)>豆类(0.16%)>食糖(0.02%).(3)长江流域地区人群高氯酸盐暴露途径主要为饮用水,其他流域地区的主要暴露途径为植物类食物.

Perchlorate can interfere with the body’s ability to absorb iodine, which can result in iodine deficiency. The primary clinical symptoms of iodine deficiency are hypothyroidism and brain development disorders. Due to its toxicity, wide spread attention has been paid in recent years to the sources and safety threshold of perchlorate exposure in humans. Although the Chinese government has carried out a general survey on sources of environmental pollution throughout the country, a major gap still exists with respect to information concerning perchlorate. It is urgent to conduct a risk assessment and carry out research concerning control strategies for perchlorate production and human exposure. Water quality standards are an effective means of pollution supervision and regulation. To this end, the different levels of contribution to perchlorate exposure from various water sources are essential to setting water quality standards. Due to the wide range of industrial production in China, perchlorate exposure has strong regional characteristics. Thus, it is impossible to directly compare the contributions of different exposure routes of perchlorate in China to exposures that occur abroad. In addition, China still lacks a nationwide assessment mechanism that can contribute specific information concerning how perchlorate exposure occurs(i.e., intake pathways) in the Chinese population.Therefore, this study is based on statistical information derived from drinking water quality monitoring data obtained from key cities in China from 2009 to 2012. When combined with the dietary intake of Chinese, the potential exposure of Chinese residents to perchlorate from the three major exposure routes, ingestion, respiration, and dermal contact is assessed for 14 major cities in China. Specifically, simulations are used to estimate the expected distribution and rate of perchlorate exposure in these 14 cities. The different rates of perchlorate exposure from drinking water from different watershed areas are also analyzed. The following results are obtained.(1) The concentration of perchlorate in tap water rangs from 0.149 to 152 μg/L. There are significant differences in pollution levels in the different provinces that are assessed. The most serious pollution levels are observed in Wuhan, Shanghai, and Chengdu.(2) The contribution of perchlorate exposure from respiration and dermal contact is minimal and measured 0.88% and 0.27%, respectively. Our results reveal that ingestion is the primary exposure route. Specifically, drinking water, cereals, and vegetables account for approximately 92% of the total exposure to perchlorate. We observe in order of highest exposure to perchlorate to the lowest as follows, vegetables(32.05%) > drinking water(32.02%) > cereals(28.12%) > meat(2.51%) > fruits(2.30%) > yam(1.85%) > milk(1.31%) >eggs(0.87%) > aquatic product(0.86%) > beans(0.16%) > sugar(0.02%).(3) Drinking water is the main source of perchlorate exposure in the Yangtze River Basin, while the main source of perchlorate exposure in other basin areas is plant-based.As a whole, people in the Yangtze River Basin are exposed to high levels of perchlorate. The possible reason for these high exposures is that China is the world’s largest producer and consumer of fireworks and firecrackers. The main fireworks production sites are concentrated in the Yangtze River Basin. During the process of producing fireworks, the solid oxidant, ammonium perchlorate, is discharged into the water. Also, perchlorate discharged into the atmosphere after setting off fireworks settles in the water and soil, which results in significant groundwater contamination. Until now, China has not formulated industrial wastewater discharge standards for perchlorate. Thus, the results from this study provide important reference values that can be applied to the current development of the Yangtze River Economic Belt and the health of the regional population. These results also can provide a scientific basis for the country to formulate effective and relevant perchlorate regulations.