城市表层土壤中铅的生物可给性及其对人体的健康风险评价:以首钢厂区附近小区域为例

研究了城市表层土壤中铅的生物可给性及其无意口部摄入后对人体的健康风险.以首钢厂区附近小区域为研究区,采集65个土壤样品应用于in vitro人工胃肠模拟实验,测定其铅的生物可给性.结果表明,土壤中铅的生物可给性差异很大,胃阶段为28.83%～62.50%,小肠阶段为6.86%～45.71%,而其大小和土壤中铅总量的高低没有直接关系;铅在胃肠道中的溶解态量与其在土壤中总量的高值分布区域比较一致;与交通及机动车辆关系较密切的样点的土壤中铅的溶解态量较高,而生物可给性较低.此外,无意口部摄入的土壤铅对人体铅的每周允许摄入量贡献率的分析表明,土壤中铅对人体并没有很高的健康风险,仅是以胃阶段结果进行判断时,其对儿童的风险较高,在研究区西北部出现了5个贡献率超过10%的样点,最大值达到25.37%;土壤铅对儿童的健康风险要高于对成人的;只有铅含量较高且生物可给性较高的土壤,才会对人体健康产生较高的风险.

Bioaccessibility of Lead in Urban Topsoil and Its Health Risk Assessment: A Case Study of a Small Area near Shougang Group

Bioaccessibility and health risk of lead in urban topsoil after unconscious oral ingestion were studied. 65 topsoil samples were collected from a small area near Shougang Group, and then bioaccessibility of soil lead was measured by means of in vitro digestion test. Results showed that the bioaccessibility of soil lead covered a wide range (28.83%-62.50% in gastric phase, and 6.86%-45.71% in intestinal phase), and had no relation to its total concentration. It was also found that the high-value areas of the gastrointestinal dissolved concentration of soil lead distributed in nearly the same way as those of its total concentration. Besides, high gastrointestinal dissolved concentration and low bioaccessibility of soil lead were observed in the sample sites close to traffic and vehicles. Due to low contribution rate of the bioaccessible amount of soil lead to the provisional tolerable weekly intake (PTWI), the health risk of soil lead in the studied area was generally low. Only when health risk assessment was based on the gastric data of children (the worst case), the sample with highest contribution rate, 25.37%, was found in the northwestern part of the studied area, where the other 5 samples with contribution rate over 10% were also located. It was obvious that the health risk of soil lead to children was higher than that to adults. Due attention should be paid to the soil with both high total concentration and high bioaccessibility of lead, as it might pose high risk to the health of general public.