ABSTRACT
PURPOSE: The present report describes the distribution of breast milk and urinary free and total bisphenol A (BPA) concentrations, from 27 postpartum women and their 31 infants, and explores the influence of age, sex, and nutritional source on infant BPA urinary concentration. METHODS: Both free (unconjugated) and total (free plus conjugated) BPA concentrations from women's breast milk samples and infants' urine samples were measured by online solid-phase extraction coupled to high-performance liquid chromatography-isotope dilution tandem mass spectrometry. Descriptive statistics and nonparametric tests of group comparisons were conducted. RESULTS: Total BPA was detected in 93 % of urine samples in this healthy infant population aged 3-15 months who were without known environmental exposure to BPA [interquartile range (IQR) = 1.2-4.4 µg/L)]. Similarly, 75 % of the mothers' breast milk samples had detectable concentrations of total BPA (IQR = 0.4-1.4 µg/L). The magnitude and frequency of detection of free BPA in the children's urine and the mothers' breast milk were much lower than the total concentrations. CONCLUSIONS: Total BPA was detected in 93 % of this healthy infant population aged 3-15 months who are without known environmental exposure to BPA. Neither free nor total BPA urinary concentrations differed significantly by infant's sex or by nutritional source (breast milk and/or formula) while age group was of borderline significance. There were no significant correlations between free or total BPA concentrations in mothers' breast milk and their infants' urine.
Subject(s)
Benzhydryl Compounds/analysis , Environmental Monitoring , Environmental Pollutants/analysis , Milk, Human/chemistry , Phenols/analysis , Adult , Benzhydryl Compounds/urine , Chromatography, High Pressure Liquid , Environmental Pollutants/urine , Female , Humans , Infant , Male , Massachusetts , Phenols/urine , Pilot Projects , Solid Phase Extraction , Tandem Mass SpectrometryABSTRACT
BACKGROUND: Although the comet assay has potential value for measuring DNA damage in large epidemiological human sperm studies, it is impractical to perform the assay daily on fresh semen samples. Therefore, before its use in epidemiological studies, the reliability of the comet assay in measuring DNA damage in cryopreserved sperm should be compared with that in fresh human sperm. METHODS: Semen samples from 16 men were cryopreserved in liquid nitrogen (LN) using four methods: flash freezing with and without cryopreservative, and programmable freezing with and without cryopreservative. Neutral microgel electrophoresis was performed and comets were stained with YOYO-1. Comet length was measured using an eyepiece micrometer at x400 magnification. RESULTS: The highest correlation was between comet assay results obtained from fresh human semen compared with semen flash frozen without cryopreservative (R = 0.88). However, the method of cryopreservation, as compared with other sources of variability, accounted for only 6% of the variability. Inter-individual variability accounted for 20%, and individual sperm-to-sperm variability within an ejaculate accounted for 65%. CONCLUSIONS: Flash-freezing in LN without cryopreservative most closely reproduced the results obtained using fresh human semen samples, and thereby represents the most appropriate cryopreservation method for human semen in epidemiological studies utilizing the neutral comet assay.
