Pesticides in human milk collected from Jinhua, China: Levels, influencing factors and health risk assessment.

In China, many studies have been carried out on pesticide residues in human milk, yet all of them are on organochlorine pesticides (OCPs) and mostly focused on large, economically developed cities. In this study, 27 pesticides including OCPs, pyrethroid pesticides (PYRs) and organophosphate pesticides (OPPs) in human milk were investigated in Jinhua, an inland and medium sized city in China. Method based on QuEChERS extraction and gas chromatography-mass spectrometer (GC-MS) determination was adopted to analyze the above pesticide residues. The influencing factors as well as the health risks were also evaluated. Results show that PYRs and OPPs in human milk samples were both undetectable. Regarding OCPs, the detection rate of hexachlorobenzene (HCB), ß-hexachlorocyclohexane (ß-HCH) and p,p'-dichlorodiphenyl-dichloroethylene (p,p'-DDE) were 83.6%, 36.4% and 58.2%, respectively, and their mean value were 29.4, 32.0 and 85.2 ng/g lipid, respectively. p,p'-DDE levels in human milk was significantly (p < 0.05) related to maternal age, but no association was detected between OCPs residues and other factors (living environment, dietary habit, living style, etc.), suggesting that OCPs in human milk in Jinhua were originated from nonspecific source. All estimated daily intake of pesticides (EDIpesticides) by infants were under the guideline suggested by Food and Agriculture Organization (FAO) and China Ministry of Health (CMH). Yet 9% of EDIsHCB and 16% of EDIsHCHs exceeded the guideline recommended by Health Canada. The associations between DDE residues and the delivery way as well as HCBs residues and the birth weight were seemly significant, yet the significance disappeared when consider age or gestational age as a cofounder, indicating that OCPs residue in mother's body in Jinhua has no obvious influence on fetus development and the delivery way.

Pairwise interaction enthalpies of enantiomers of ß-amino alcohols in DMSO + H2O mixtures at 298.15 K.

The dilution enthalpies of enantiomers of six ß-amino alcohols, namely (R)-(-)-2-amino-1-propanol versus (S)-(+)-2-amino-1-propanol, (R)-(-)-2-amino-1-butanol versus (S)-(+)-2-amino-1-butanol, and (R)-(-)-2-amino-1-pentanol versus (S)-(+)-2-amino-1-pentanol in dimethylsulfoxide (DMSO) + H(2)O mixtures (mass fractions of DMSO w = 0 to 0.3) have been determined respectively using an isothermal titration calorimeter (MicroCal ITC200, Northampton, MA, USA) at 298.15 K. According to the McMillan-Mayer theory, the corresponding homochiral enthalpic pairwise interaction coefficients (h(XX)) of the six amino alcohols have been calculated. It is found that across the whole studied composition range of mixed solvent, values of h(XX) for S-enantiomer are almost universally higher than those of R-enantiomer for each amino alcohol and that the variations of h(XX) depend largely on the composition of mixed solvent. The results were interpreted from the point of view of solute-solute interaction mediated by cosolvent DMSO, as well as competition equilibrium between hydrophobic-hydrophobic, hydrophilic-hydrophilic, and hydrophobic-hydrophilic interactions.