Monitoring Of Pollutants In Breast Milk In Jinhua City And Assessment Of Maternal And Infant Health Risks

Breast milk offers most nutrition for the infants,which helps the baby to resist disease infection and grow up healthily.Organs of infant at this stage are immature,and the activity of metabolic enzymes that have detoxification is low.Therefore,it is necessary to pay special attention to the residues of toxic pollutants in breast milk.However,most of the studies on the residues of pollutants in breast milk in China are concentrated in the economically developed cities and coastal cities,and the levels and laws of the residues of pollutants in breast milk varied from place to place.The current research still could not provide effective reference for the pollution of breast milk in other places.Bearing above information,this study investigated the residues of typical pollutants in breast milk of Jinhua,a small and medium-sized inland city in China.The pollutants included organochlorine pesticides（OCPs）,organophosphorus pesticides（OPPs）,pyrethroid pesticides（PYRs）,polycyclic aromatic hydrocarbons（PAHs）and heavy metals（Hg,Pb,Cr,Cd）were determined.With the help of questionnaire,the potential influence factors on pollutants level in breast milk were identified and the health risks on infants were assessed.The main results are shown as follows:（1）Pollutant levels:PYRs and OPPs were not detected in breast milk samples in Jinhua City.Only three OCPs,namely p,p’-DDE andβ-HCH and HCB,were detected,and their average levels were 85.2,32.0,and 29.4 ng g^-1 lipid,respectively.For PAHs,naphthalene,phenanthrene,fluoranthene,and pyrene were detected,and the average values were 50.6,41.2,4.8,and 1.4 ng g^-1 lipid,respectively.The average levels of Hg,Pb,Cr,and Cd were 0.65,0.93,1.02,and 0.85μg L^-1,respectively.Compared with the levels in other regions at home and abroad,the pollutants detected in breast milk in Jinhua are generally at a lower level.（2）Influencing factors:The level of p,p’-DDE in breast milk increased with the age of the parturient,suggesting that age is an important factor affecting its level.PAHs level in breast milk is mainly affected by parity,passive smoking and exercise frequency;higher concentrations of PAHs were detected in the breast milk of the pregnant women who had born with first delivery,passive smoking and low exercise frequency.For heavy metals,higher Hg level was found in the breast milk of mothers with higher pre-pregnancy BMI,indicating that mothers with higher pre-pregnancy BMI due to more fat in body may accumulate more mercury.Further analysis also showed that Hg in maternal breast milk was positively correlated with the frequency of maternal consumption of takeaways,and negatively correlated with the usage of mosquito killer products and exercise frequency,suggesting that frequent exposure to takeaways and plastic lunch boxes may increase the risk of Hg enrichment,but the pyrethroid compounds in mosquito killer products and exercise metabolism may accelerate the elimination of Hg in the mother’s body.（3）Health risks:（1）Correlation and group analysis show that the levels of pollutants in maternal breast milk are not significantly correlated with infant birth indicators（height,weight,etc.）.However,PAHs in breast milk are positively correlated with the frequency of antenatal dysmenorrhea in women,PAHs level in breast milk of the middle gestational age group was significantly lower than those of the longer and shorter gestational age group,indicating that PAHs may interfere with the gestational age and menstruation,and affect the reproductive health of the parturient.（2）For pesticides in breast milk,the estimated daily intake did not exceed the provisional tolerable daily intake（PTDI）or acceptable daily intake（ADI）recommended by Food and Agriculture Organization（FAO）or the Chinese Ministry of Health（CMH）,but it cannot be ignored that 9%of HCB and 16%ofβ-HCH still exceeded the acceptable tolerable daily intake（TDI）established by Health Canada.For PAHs,the daily intakes（DI）of detected naphthalene,phenanthrene,fluoranthene and pyrene are 0.21±0.25,0.18±0.28,0.20±0.033,0.0059±0.019 ng kg^-1 day^-1,respectively.After conversion to the equivalent concentration of benzo[a]pyrene（Ba P）,DI were far lower than the upper limit of Ba P intake dose given by relevant institutions.However,the average value of cancer risk（CR）was 1.51×10^-6,indicating that the risk of cancer in infants after ingestion of breast milk containing PAHs is about one in a million.For heavy metals,the estimated weekly intake of Pb,Cd,and Hg by infants through breast milk is lower than the tolerable intake given by the relevant agencies.