Silicone Ankle Bands as a Tool to Assess Infant Exposures to Semivolatile Organic Chemicals in Indoor Environments

Exposure to organophosphate esters (OPEs), used as flame retardants and plasticizers, is highly variable in the general population, and limited data exist on exposures in young children. This study evaluated the use of silicone ankle bands to assess OPE exposure in infants under 18 months of age. Infants (n = 21) wore silicone ankle bands for three consecutive days, and spot urine samples were collected using either pediatric urine collection bags or toddler training toilets. Ankle bands were analyzed for 20 OPEs; seven were detected in >70% of samples. TDCIPP and TPHP were the most abundant compounds on bands (medians = 57.5 and 53.0 ng/g, respectively). All targeted urinary metabolites were detected in most samples, with BDCIPP being the most abundant biomarker (median = 3.7 ng/mL SG-corrected), 2.5 times higher than DPHP. Significant positive correlations were observed between urinary metabolites and parent compounds on the ankle bands (rs = 0.40–0.73, p < 0.05), suggesting that silicone samplers reliably capture exposure trends. These findings support ankle bands as a practical, noninvasive tool for assessing OPE exposures in infants, offering an alternative to urine-based biomonitoring.