饮水中甲萘威短期暴露健康影响研究

目的针对饮水中污染物甲萘威的短期暴露健康参考值开展验证工作。方法选择健康Wistar大鼠126只,雌雄各半,随机分为7组,1个阴性对照组和6个甲萘威受试物组,以玉米油为阴性对照,对Wistar大鼠给予浓度为0、5、10、20、40、80、160 mg/(kg·d)的甲萘威。每周称量大鼠体重,于染毒后8、15、29 d每组分别取6只大鼠,雌雄各半,检查血生化指标,解剖后取肝、肾、脾、肺、胸腺、脑进行组织病理学检查。结果大鼠体重及脏体比指标中,只有染毒28 d后160 mg/(kg·d)剂量组肾脏体比与阴性对照组相比显著降低,差异有统计学意义(P<0.05)。大鼠血清酶学指标中,只有染毒7 d后AST在80 mg/(kg·d)剂量组与阴性对照组相比显著降低,差异有统计学意义(P<0.05)。大鼠血常规指标中,染毒7 d后,与阴性对照组相比血红蛋白在20、40、160 mg/(kg·d)剂量组显著升高(均P<0.05);染毒14 d后,白细胞计数在5、10、160 mg/(kg·d)剂量组、平均红细胞血红蛋白含量在160 mg/(kg·d)、平均血小板体积在10、160 mg/(kg·d)、平均红细胞血红蛋白浓度在160 mg/(kg·d)、血小板分布宽度在5、80 mg/(kg·d)剂量组,均与阴性对照组相比显著增加且差异有统计学意义(均P<0.05)。染毒28 d后,与阴性对照组相比白细胞计数在20、80 mg/(kg·d)、平均红细胞血红蛋白浓度在80、160 mg/(kg·d)剂量组中均显著增加(均P<0.05)。在乙酰胆碱酯酶活性指标中,与阴性对照组相比,染毒7 d后,红细胞乙酰胆碱酯酶活性在40 mg/(kg·d)剂量组显著降低;染毒14 d后,红细胞乙酰胆碱酯酶活性在80 mg/(kg·d)剂量组显著升高,脑组织乙酰胆碱酯酶活性在160 mg/(kg·d)剂量组显著降低;染毒28 d后,脑组织乙酰胆碱酯酶活性从20 mg/(kg·d)剂量组开始显著降低,红细胞乙酰胆碱酯酶活性在40 mg/(kg·d)剂量组显著升高,差异均有统计学意义(均P<0.05)。组织病理学指标在染毒7、14、28 d后各剂量组与阴性对照组相比均未有明显变化(均P>0.05)。结论大鼠短期经口摄入甲萘威无可见有害作用水平(no observed adverse effect level,NOAEL)为10 mg/(kg·d),利用其所推导的甲萘威短期暴露健康风险健康参考值为1 mg/L,与美国EPA推荐值相同。

Health impact of short-term exposure to carbaryl in drinking water

Objective To validate health-based advisory for short-term exposure to carbaryl in drinking water. Methods One hundred and twenty-six healthy Wistar rats, half males and half females, were randomly divided into 7 groups. The rats in the negative control group were fed orally with corn oil, while the rats in the other six groups were administered orally with carbaryl 5, 10, 20, 40, 80 and 160 mg/kg per day.All rats were weighted once a week. After 8, 15 and 29 days of administration, 6 rats in each group, half males and half females, were sacrificed to detect blood biochemical parameters, and liver, kidney, spleen, lung, thymus and brain of each rat were collected for pathological examination. Results Among the rats’ body weight and visceral body ratios, after 28 days of exposure, only the kidney body ratio of the 60 mg/(kg·d) dosage group decreased compared with the negative control group, with a statistically significant difference (P<0.05). Among the serum biochemical indexes, after 7 days of exposure, only aspartate aminotransferase (AST) of the 80 mg/(kg·d) dosage group declined significantly compared with the negative control group (P<0.05). Among the indicators of blood routine, after 7 days of exposure, hemoglobin of the 20, 40 and 160 mg/(kg·d) dosage groups increased significantly compared with the negative control group (all P<0.05). After 14 days of exposure, the white blood cell count of the 5, 10 and 160 mg/(kg·d) dosage groups, the hemoglobin content of average red blood cell of the 160 mg/(kg·d) dosage group, the average platelet volume of the 10 and 160 mg/(kg·d) dosage groups, the hemoglobin concentration of average red blood cell of the 160 mg/(kg·d) dosage group and platelet distribution width of the 5 and80 mg/(kg·d) dosage groups increased significantly compared with the negative control group, showing statistically significantdifferences (all P<0.05). After 28 days of exposure, the white blood cell count of the 20 and 80 mg/(kg·d) dosage groups and the hemoglobin concentration of average red blood cell of the 80 and 160 mg/(kg·d) dosage groups increased significantly compared with the negative control group (all P<0.05). In the index of acetylcholinesterase activity, after 7 days of exposure, the erythrocyte acetylcholinesterase activity of the 40 mg/(kg·d) dosage group decreased significantly compared with the negative control group. After 14 days of exposure, erythrocyte acetylcholinesterase activity of the 80 mg/(kg·d) dosage group increased significantly compared with the negative control group, while the acetylcholinesterase activity in brain tissue of the 160 mg/(kg·d) dosage group decreased significantly. After 28 days of exposure, acetylcholine enzyme activity in brain tissue of the 20 mg/(kg·d) dosage group decreased significantly, while erythrocyte acetylcholinesterase activity of the 40 mg/(kg·d) dosage group increased significantly, with statistically significant differences (all P<0.05). After 7, 14, and 28 days of exposure, no significant changes were observed in histopathological indicators of each dosage group compared with the negative control group (all P>0.05). Conclusions The no observed adverse effect level (NOAEL) of short-term oral intake of carbaryl in the rats is 10 mg/(kg·d), and the health-based advisory for short-term exposure to carbaryl is 1 mg/L, which is the same as the U.S.Environmental Protection Agency (EPA) recommendation.