Study On The Mother And Infant Body Burden And The Exposure Estimation Of Persistent Organochlorine Pesticides

Persistent Organochlorine pesticides (OCPs) were a kind of synthetic broad-spectrum pesticides, the use of which has been banned currently.In this study, with the necessity of carrying out the effective assessment according to the National Implementation Plan (NIP) to implementing the POPs Convention, and through the breast-monitoring and total diet studies as the means of monitoring the priority list of the Convention on the OCPs (Toxaphene, pentachlorobenzene, Kepone excluded) recommended by the World Health Organization (WHO), the levels of persistent OCPs were detected in breast milk samples from 12 provinces in China to monitor the human burden levels of OCPs, and the levels of OCPs were detected in food which obtained by the total diet study in 2007. It is the first time to evaluate the internal exposure (body burden) and the external exposure (dietary intake) of OCPs in a representative population and the results will be the baseline for future assessment.1. The methodology for determination of persistent OCPsIn order to assess human burden and dietary exposure of OCPs of Chinese adults and infants, a NCI-GC-MS method with Isotope dilution technique was developed for simultaneous determination of 9 persistent OCPs (23 compounds) in 24 pooled human milk samples and 9 categories of food samples which were collected in 2007 from 12 provinces of China. The target 23 compounds included DDT and its metabolite (p,p'-DDT, o,p'-DDT, p,p'-DDE, o,p'-DDE, p,p'-DDD and o,p'-DDD), HCH isomers (α-,β-,γ-andδ-HCH), aldrin, dieldrin, endrin, chlrodanes (oxychlordane, cis-chlordane, trans-chlordane, trans-nonchlor and cis-nonchlor), heptachlors (heptachlor, cis-heptachlor epoxide, trans-heptachlor epoxide), mirex and Hexachlorobenzene. The methodology was based on solid-liquid extraction or liquid-liquid extraction, GPC cleanup with SPE cleanup, and isotope dilution. Breast milk samples were extracted by Soxhlet extraction or accelerated solvent extraction (ASE) and food samples were extracted by liquid- liquid extraction or accelerated solvent extraction (ASE). The extract was SPE cleanup followed by gel permeation chromatography (GPC) pretreatment. The separation was carried out on a VF5-5MS capillary column. A triple quadrupole mass spectrometer equipped with negative chemical ionization mode and selected ion monitoring (SIM) was employed for quantitative measurement. The laboratory performance was validated by participating in Food Analysis Performance Assessment Scheme (FAPAS). Proficiency Test for OCPs in fish oil and milk powder was organized by the Central Science Laboratory of UK in 2007 and 2008, respectively. Z-score for OCPs was<2.0. The laboratory also participated in the First Worldwide UNEP Intercalibration Study on Persistent Organic Pollutants in October 2009. The good results were obtained for the test solutions, fish sample, and human milk sample which demonstrated that the NCI-GC-MS method developed is highly effective for analyzing trace amounts of OCPs in breast milk and foods. Our study can provide powerful technique basis for National Implementation Plan for Persistent Organic Pollutants (NIP)2. Levels of OCPs in breast milk samples and mother and infant burden levels of OCPs in ChinaA number of 1237 primiparous breast milk samples were collected from 12 provinces in 2007. In each province, one urban site and two rural sites were selected for sampling. These 36 regions were the same sampling sites for Chinese Total Diet Study (TDS) in 2007. For each province, the urban individual samples were pooled into one pooled sample and rural individual samples were also pooled. Concentrations of 9 OCPs (23 compounds) in 24 pooled breast milk samples were simultaneously detected by GC-NCI-MS with Isotope dilution technique. The results showed that DDTs, HCHs and HCB were predominant OCPs in the breast milk in China. The average levels of DDTs, HCHs and HCB were 584.3±362.3,231.8±123.4 and 33.1±11.1 ng/g lipid wt, respectively. Compared with the previous data, DDTs was controlled well since 1983 but the breast milk from Fujian province indicated that there were the new contaminants of DDTs. The level of DDTs in breast milk from south was higher than that from north. A significant Pearson correlation was found (r=0.659, p<0.05) between the consumption of animal origin food and the level of DDTs in breast milk in the study. The level of HCHs in breast milk showed the decreased trend in China. The contaminants HCHs by dietary exposure in many areas, especially Heilongjiang province were eliminated. Animal origin food, especially seafood was the main source of human exposure to HCHs. The average level of HCHs in breast milk from urban samples was higher than those from rural samples in China (P<0.05). HCB was a man-made by-product found in breast milk and dietary. In the Worldwide, DDTs, HCHs and HCB concentrations in breast milk in China was in the medium level. For the 0-6 month infant exposure to DDTs, HCHs, heptachlor, aldrin/dieldrin, endrin, lindane and mirex, the average daily intake estimates were lower than the PTDI. However, EDI of DDTs and HCHs of 0-6 month baby in some provinces were close to or above PTDI. Therefore, the ongoing monitoring of persistent OCPs of breast milk is quite necessary in China.3. Levels of OCPs in food samples and dietary exposure estimation of OCPs in China. On the basis of NCI-GC-MS analysis,9 OCPs (23 compounds) were determined in 108 Chinese total diet study (TDS) samples collected from 12 provinces in 2007. The 9 food groups included cereals, legumes, potatoes, meat, egg, aquatic foods, milk, vegetables and fruits. The results showed that aquatic foods and meat were the main source in the total dietary intake of OCPs. The level of DDT ranged from ND to 15.66μg/kg and p,p'-DDE was predominant compound; the level of HCH ranged from ND to 0.79μg/kg; the level of HCB ranged from 0.03 to 2.06μg/kg; the level of chlordane ranged from ND to 1.15μg/kg; the level of heptachlor ranged from ND to 0.32μg/kg. Daily dietary intakes of OCPs for the Chinese were estimated by multiplying the measured concentrations of OCPs with the daily consumption data. The lower limit (ND=0) and upper limit (ND=LOD) EDI DDT for a "reference" man (male adult,63kg bodyweight) via 9 categories foods was 0.016-2.713μg/kg body wt./day and the ratio EDI/PTDI was 0.16-27.13%; that of HCH was 0.002-0.165μg/kg body wt./day and the ratio EDI/PTDI was 0.10-8.25%; that of HCB was 0.009μg/kg body wt./day, the ratio EDI/PTDI was3.33%%; that of EDI chlordane was 0.006-0.07μg/kg body wt./day and the ratio EDI/PTDI was 1.20-14.00%; that of EDI heptachlor was 0.001-0.075μg/kg body wt./day and the ratio EDI/PTDI was 1.00-75.00%. The results showed that the health and environmental risks of the dietary exposure of the persistent OCPs in Chinese residents were still within the range of the risk management.4. Research ProspectsOverall the level of OCPs in breast milk and foods showed a decreased trend, but it is worth to be concerned that the persistent OCPs pollution level were still high in the breast milk samples of several regions, and the EDI exceeded the corresponding PTDI. It is necessary to strengthen the national monitoring of the body burden and dietary exposure of persistent OCPs and to reduce or eliminate the pollution of persistent OCPs in order to protect human health and the environment.