Persistent organic pollutants in infants and toddlers: Relationship between concentrations in matched plasma and faecal samples.

Early-childhood biomonitoring of persistent organic pollutants (POPs) is challenging due to the logistic and ethical limitations associated with blood sampling. We investigated using faeces as a non-invasive matrix to estimate internal exposure to POPs. The concentrations of selected POPs were measured in matched plasma and faecal samples collected from 20 infants/toddlers (aged 13 ± 4.8 months), including a repeat sample time point for 13 infants (~ 5 months apart). We observed higher rates of POP quantification in faeces (2 g dry weight) than in plasma (0.5 mL). Among the five chemicals that had quantification frequencies over 50% in both matrices, except for HCB, log concentration in faeces (C f ) and blood (C b ) were correlated (r > 0.74, P < 0.05) for p . p ′-dichlorodiphenyldichloroethylene ( p , p ′-DDE), 2,3′,4,4′,5-pentachlorobiphenyl (PCB118), 2,2′,3,4,4′,5′-pentachlorobiphenyl (PCB138) and 2,2′,4,4′,5,5′-pentachlorobiphenyl (PCB153). We determined faeces:plasma concentration ratios (K fb ), which can be used to estimate C b from measurements of C f for infants/toddlers. For a given chemical, the variation in K fb across individuals was considerable (CV from 0.46 to 0.70). Between 5% and 50% of this variation was attributed to short-term intra-individual variability between successive faecal samples. This variability could be reduced by pooling faeces samples over several days. Some of the remaining variability was attributed to longer-term intra-individual variability, which was consistent with previously reported observations of a decrease in K fb over the first year of life. The strong correlations between C f and C b demonstrate the promise of using faeces for biomonitoring of these compounds. Future research on the sources of variability in K fb could improve the precision and utility of this technique. [ABSTRACT FROM AUTHOR]