Children’s Phthalate Intakes and Resultant Cumulative Exposures Estimated from Urine Compared with Estimates from Dust Ingestion, Inhalation and Dermal Absorption in Their Homes and Daycare Centers

Abstract

Total daily intakes of diethyl phthalate (DEP), di(n-butyl) phthalate (DnBP), di(isobutyl) phthalate (DiBP), butyl benzyl phthalate (BBzP) and di(2-ethylhexyl) phthalate (DEHP) were calculated from phthalate metabolite levels measured in the urine of 431 Danish children between 3 and 6 years of age. For each child the intake attributable to exposures in the indoor environment via dust ingestion, inhalation and dermal absorption were estimated from the phthalate levels in the dust collected from the child’s home and daycare center. Based on the urine samples, DEHP had the highest total daily intake (median: 4.42 µg/d/kg-bw) and BBzP the lowest (median: 0.49 µg/d/kg-bw). For DEP, DnBP and DiBP, exposures to air and dust in the indoor environment accounted for approximately 100%, 15% and 50% of the total intake, respectively, with dermal absorption from the gas-phase being the major exposure pathway. More than 90% of the total intake of BBzP and DEHP came from sources other than indoor air and dust. Daily intake of DnBP and DiBP from all exposure pathways, based on levels of metabolites in urine samples, exceeded the Tolerable Daily Intake (TDI) for 22 and 23 children, respectively. Indoor exposures resulted in an average daily DiBP intake that exceeded the TDI for 14 children. Using the concept of relative cumulative Tolerable Daily Intake (TDIcum), which is applicable for phthalates that have established TDIs based on the same health endpoint, we examined the cumulative total exposure to DnBP, DiBP and DEHP from all pathways; it exceeded the tolerable levels for 30% of the children. From the three indoor pathways alone, several children had a cumulative intake that exceeded TDIcum. Exposures to phthalates present in the air and dust indoors meaningfully contribute to a child’s total intake of certain phthalates. Such exposures, by themselves, may lead to intakes exceeding current limit values.

Phthalate exposure through different pathways and allergic sensitization in preschool children with asthma, allergic rhinoconjunctivitis and atopic dermatitis

“…Limitations regarding the estimates of daily intakes and the representativeness of a single morning urine sample were addressed in previous papers (Bekö et al, 2013;Callesen et al, 2014aCallesen et al, , 2014b. The current results suggest that attention to exposure pathways and the subject's sensitization status may help to elucidate the somewhat conflicting evidence for the associations between phthalate exposure and allergic disease.…”

“…Within a given case group and for a given phthalate, the various exposure pathways and the total indoor intakes did not correlate with sensitization equally (Tables 2 and S5; Tables 3 and S6). For example, among children with rhinoconjunctivitis by CEI, of all DEHP intake indicators only dermal absorption was significantly associated with sensitization, although only a small percentage of the total indoor intake is estimated to have come from this pathway (Bekö et al, 2013). These results are certainly not conclusive with regards to which exposure pathway for a given phthalate may be important from a health perspective, and confirmatory studies are needed.…”

“…The children's intakes of the target phthalates via inhalation, dust ingestion and transdermal absorption from air (Weschler and Nazaroff, 2012) were then estimated for both the home and daycare environments separately for a weekday and a weekend. Dermal exposure to phthalates associated with dust adhered to skin has not been considered in the present study, since in an earlier study we concluded that the contribution from dust adhered to skin was negligible (Bekö et al, 2013). In these estimates we assumed that a child spent 20 h a day in their home and daycare environments.…”

“…Further details on these estimates and the assumed input parameters (ingestion rate, inhalation rate, transdermal permeability coefficient, etc.) can be found in Bekö et al (2013). These analyses were conducted for all children for whom dust samples from both home and daycare center were available.…”

Endocrine-disrupting chemicals and skin manifestations

“…Prenatal exposure to BBzP, as measured by levels of MBzP in spot urine samples during the third trimester of pregnancy, has been associated with a risk of developing eczema in early childhood [27]. In children eczema and allergic sensitization, significant associations have been established between non-dietary exposure to DnBP, BBzP, and DEHP in the indoor environment including a daily indoor intake from dust ingestion, inhalation, and dermal absorption [28]. A recent study showed that filaggrin gene variants may increase skin permeability leading to higher skin absorption of phthalates and, therefore, a higher susceptibility for atopic dermatitis [29].…”