Pollution characteristics and human health risks of PM2.5-bound heavy metals: a 3-year observation in Suzhou, China.

This study aimed to analyze the temporal trends, pollution levels, and health risks associated with eleven PM2.5-bound heavy metals (Sb, Al, As, Hg, Cd, Cr, Mn, Ni, Pb, Se and Tl). A total of 504 PM2.5 samples were collected in Suzhou from January 2019 to December 2021. The pollution levels were estimated based on enrichment factors (EFs) which can be used to calculate the enrichment of heavy metals in PM2.5 and determine whether the concentrations of PM2.5-bound heavy metals are influenced by the crustal or anthropogenic sources, and the health risk of PM2.5-bound heavy metals via inhalation was assessed following US EPA's Risk Assessment Guidance for Superfund (RAGS). The annual average concentration of PM2.5 was 46.76 µg m-3, which was higher than the WHO recommended limit of 5 µg m-3. The average of the sum of eleven PM2.5-bound heavy metals was 180.61 ng m-3, dominated by Al, Mn, and Pb. The concentration of PM2.5 in 2020 was significantly lower than that in 2019 and 2021. The PM2.5 and PM2.5-bound heavy metal concentrations in winter and spring were significantly higher than those in autumn and summer. The EF of As, Cr, Cd, Hg, Ni, Pb, Sb, Mn, Se, and Tl was higher than 10, indicating they were mainly from anthropogenic sources. Exposure to a single non-carcinogenic heavy metal via inhalation was unlikely to cause non-carcinogenic effects (HQ < 1), but the integrated non-carcinogenic risks should be taken seriously (HI > 1). The cumulative carcinogenic risks from the carcinogenic elements were exceeding the lower limit (1 × 10-6) of the acceptable risk range. The carcinogenic risks of As and Cr(VI) contributed 60.98% and 26.77%, respectively, which were regarded as two key carcinogenic risk factors. Overall, the government policies and countermeasures for the PM2.5 pollution control should be performed not only based on the PM2.5 concentration but also based on the PM2.5-bound heavy metals and their health risks for the local residents.

[Acute risk assessment of cumulative dietary exposure to organophosphorus pesticide among people in Jiangsu province].

OBJECTIVE: To understand the cumulative dietary exposure of Jiangsu residents to organophosphorus (OPs) pesticide and make acute risk assessment. METHODS: Integrated the data of the nutrition and health status of residents in Jiangsu and the data of monitoring of OPs pesticide in agricultural products. Chlorpyrifos was selected as index compound (index chemical, IC), then use relative potency factor (RPF) approach which commended by EPA and simple distribution evaluation. Caloulated the dietary cumulative exposure of OPs pesticide among Jiangsu residents and compared with acute reference dose (ARfD), then made risk assessment. RESULTS: The exposure of rural group of age 3-6 and 7-11 were 133.84 microg/kg BW and 154.32 microg/kg BW, exceeded ARfD. The exposure level of kids and elder was higher than adults. The exposure level of rural residents were higher than urban residents. The highest contribution to the food of each age group was greengrocery and leek. CONCLUSION: The average level of exposure was safety in Jiangsu, high exposure children were at acute poisoning risk. High contribution food such as greengrocery and leek should be strengthen monitoring.

[Impacts that dimethoate inhibited the benchmark dose of acetylcholinesterase based on experimental designs].

OBJECTIVE: To obtain the impacts of experimental design on benchmark dose (BMD), and the result was applied to test the computer simulation by software Slob (optimal method to calculate the BMD: for a certain sample capacity, to add the experimental groups by reducing the amount of animals in each group) , consequently, this method can be widely used in the future. METHODS: Eighty adult female SD rats were ig given dimethoate 0.5, 1, 2, 4, 8, 16 and 32 mg/kg for 21 d, respectively. Rats were sacrificed, and acetylcholinesterase (AChE) activity in the hippocampus, cerebral cortex and serum of rats was determined after dimethoate was ig given to rats for 21 d. And then, the software package PROAST28.1 was applied to calculate the BMD. The four does groups of 10 animals (4 x 10 design) and 8 x 5 design were selected from 8 x 10 design to study the impacts of experimental design on BMD. RESULTS: Comparing with the normal control, the significant decline of AChE in hippocampus was observed in 2, 4, 8, 16 and 32 mg/kg groups (P < 0.05), whereas the significant decrease was obtained in 0.5, 1, 2, 4, 8, 16 and 32 mg/kg groups (P < 0.05). Taking the 8 x 10 design as the standard, the confidence interval of BMD calculated by both of 4 x 10 design and 8 x 5 design covered the BMD by 8 x 10 design. And also, confidence interval of BMD, calculated by design scheme 1, 2, 3, 4 and 6 of 4 x 10 design, wider than that of 8 x 5 design, but its scheme 5 narrower than 8 x 5 design. CONCLUSION: To add experimental groups in a certain sample capacity was the optimal method to calculate BMD, but was not the common toxicity experimental design (e. g. set four groups including control, low-dose, moderate-dose, high-dose group).