Co-exposure to non-persistent organic chemicals among American pre-school aged children: A pilot study

General population human biomonitoring programs such as the National Health and Nutrition Examination Survey (NHANES) in the United States suggest that chemical exposures are common. Exposures during childhood may affect health later in life, but biomonitoring data in NHANES among pre-school aged children are limited.

A convenience group of 122 3-5year old American boys and girls were recruited in 2013 for a pilot study to assess the feasibility of collecting urine from young children and analyzing it for select chemical exposure biomarkers for future NHANES. Children were primarily Hispanic (64.8%); the remainder was divided between non-Hispanic black, and non-Hispanic white and "other." We measured 52 urinary biomarkers: 13 phthalates and one non-phthalate plasticizer, five phenols and four parabens, 10 polycyclic aromatic hydrocarbons (PAHs), and 19 pesticides. For each biomarker, we calculated descriptive statistics. We also calculated the number of biomarkers detected within each child, and performed principal components analysis (PCA).

NHANES staff obtained permission to attempt collection of 60mL urine from 3 to 5year olds who participated in the 2013 NHANES health examination; 83% of children successfully provided the target volume. We detected 24 individual biomarkers of pesticides, phenols and parabens, phthalates/non-phthalate plasticizers, and PAHs in 95-100% of children. The median number of biomarkers detected was 37: nine pesticides, five phenols and parabens, 13 phthalates and non-phthalate plasticizers, and 10 PAHs. Biomarkers concentrations appear to be similar to national estimates among 6-11year old children from previous NHANES. PCA suggested high within-class correlations among biomarkers.

These young children successfully adhered to the collection protocol and produced enough urine for the quantification of environmental biomarkers currently being measured in NHANES participants 6 years of age and older. Using the same analytical methods employed for the analysis of samples collected from older NHANES participants, in this sample of pre-school aged children we detected multiple chemicals including plasticizers, combustion products, personal-care product chemicals, and pesticides. Starting with NHANES 2015-2016, the NHANES biomonitoring program will include urinary biomarkers for 3-5year old children to provide exposure data to select chemicals at the national level among this age group.