Excretion Rate and Accumulating Rate of p, p'-DDE in Beijing Resident during Consecutive Lactation
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ABSTRACT
BACKGROUNDMonitoring of p, p'-DDE in breast milk was a significant way to evaluate the p, p'-DDE accumulation level in human beings within a short-term and calculate daily intake for infants. Although the investigation of classic organic chlorine pesticides in Beijing breast milk showed that p, p'-DDE was detected with the highest residue level. The study on the accumulating rate of p, p'-DDE, indicated a dynamic and long-term change, in Beijing females this was neglected and scarce.OBJECTIVESTo detect p, p'-DDE in breast milks from two consecutive lactations, estimate the excreted speed during each lactation along with the impact of delivery times on residue level of p, p'-DDE in mothers, and estimate its annual accumulating rate in Beijing residents.METHODSDuring 2009-2019, breast milk samples were collected from 43 mothers during their first lactation and 18 of them during their two consecutive lactations. The concentration of p, p'-DDE in breast milk was determined by gas chromatography.RESULTSThe analytical results showed that the p, p'-DDE in breast milk decreased continuously during each lactation. Age and the number of childbirths were the influencing factors of the concentration of p, p'-DDE in breast milk. The concentration of p, p'-DDE increased with the age of mothers and decreased with the number of childbirths. In addition, the average excretion speed of p, p'-DDE in breast milk from 18 twice-birth mothers decreased from 18.9μg/kg lipids per month within the first lactation to 16.8μg/kg lipids per month within the second lactation. The estimated value of the annual enrichment rate of p, p'-DDE in the interval between two births of the mother was positive, from 10.9μg/kg lipids per year to 14.9μg/kg lipid per year during the consecutive deliveries. Daily intake of p, p'-DDE was from 29.8ng/day/kg.b.w. to 40.8ng/day/kg.b.w..CONCLUSIONSThe depurated dose of p, p'-DDE in mothers within a month of lactation was equal to the accumulating dose in a year. The estimated daily intake of p, p'-DDE was far lower than the suggested value of WHO. The Beijing female was in a low exposure risk environment.
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