Impact of Skin Care Products on Phthalates and Phthalate Replacements in Children: the ECHO-FGS

Abstract

Background: Phthalates and their replacements have been implicated as developmental toxicants. Young children may be exposed to phthalates/replacements when using skin care products (SCPs).

Objectives: Our objective is to assess the associations between use of SCPs and children's urinary phthalate/replacement metabolite concentrations.

Methods: Children (4-8 years old) from the Environmental Influences on Child Health Outcomes-Fetal Growth Study (ECHO-FGS) cohort provided spot urine samples from 2017 to 2019, and mothers were queried about children's SCP use in the past 24 h ($n=906$). Concentrations of 16 urinary phthalate/replacement metabolites were determined by liquid chromatography-tandem mass spectrometry ($n=630$). We used linear regression to estimate the child's use of different SCPs as individual predictors of urinary phthalate/replacement metabolites, adjusted for urinary specific gravity, age, sex assigned at birth, body mass index, and self-reported race/ethnic identity, as well as maternal education, and season of specimen collection. We created self-organizing maps (SOM) to group children into "exposure profiles" that reflect discovered patterns of use for multiple SCPs.

Results: Children had lotions applied (43.0%) frequently, but "2-in-1" hair-care products (7.5%), sunscreens (5.9%), and oils (4.3%) infrequently. Use of lotions was associated with 1.17-fold [95% confidence interval (CI): 1.00, 1.34] greater mono-benzyl phthalate and oils with 2.86-fold (95% CI: 1.89, 4.31) greater monoethyl phthalate (MEP), 1.43-fold (95% CI: 1.09, 1.90) greater monobutyl phthalate (MBP), and 1.40-fold (95% CI: 1.22, 1.61) greater low-molecular-weight phthalates (LMW). Use of 2-in-1 haircare products was associated with 0.84-fold (95% CI: 0.72, 0.97) and 0.78-fold (95% CI: 0.62, 0.98) lesser mono(3-carboxypropyl) phthalate (MCPP) and MBP, respectively. Child's race/ethnic identity modified the associations of lotions with LMW, oils with MEP and LMW, sunscreen with MCPP, ointments with MEP, and hair conditioner with MCPP. SOM identified four distinct SCP-use exposure scenarios (i.e., profiles) within our population that predicted 1.09-fold (95% CI: 1.03, 1.15) greater mono-carboxy isononyl phthalate, 1.31-fold (95% CI: 0.98, 1.77) greater mono-2-ethyl-5-hydroxyhexyl terephthalate, 1.13-fold (95% CI: 0.99, 1.29) greater monoethylhexyl phthalate, and 1.04-fold (95% CI: 1.00, 1.09) greater diethylhexyl phthalate.

Discussion: We found that reported SCP use was associated with urinary phthalate/replacement metabolites in young children. These results may inform policymakers, clinicians, and parents to help limit children's exposure to developmental toxicants. https://doi.org/10.1289/EHP13937.

Figure 1.

Exposure continuum map describing frequencies of children of ECHO-FGS participants categorized into SCP-use exposure profiles using a self-organizing map ($n=906$) (numeric data in Table S11). Note: Exposure profile categories are defined based on the frequencies of participant responses to each SCP-use question and illustrated using radial bars labeled with letters indicating the average reported frequencies normalized to the range of reported frequencies in the study population; longer bars correspond to greater use. For example, exposure profiles 2 and 4 include children that reported greater use of lotions than children in exposure profiles 1 and 3. Cond., hair conditioner; Deod., deodorant; ECHO-FGS, Environmental Influences on Child Health Outcomes-Fetal Growth Study; Hair, hair products other than shampoo, conditioner, or oil; Hand., hand sanitizer; Lip., lip products; Med., medicated products; Oils, hair oil; Organic, products using only organic ingredients; Par-fr., paraben-free products; Pht-fr., phthalate-free products; SCP, personal care product; Soap, bar soap, liquid soap, and body wash; Sun., sunscreen; 2–1s, 2-in-1 shampoo and hair conditioner products; 3–1s, 3-in-1 body wash, shampoo, and hair conditioner products.

Figure 2.

Relationships between SCP-use exposure profile categories and urinary phthalate/replacement metabolite concentrations (ng/mL or nmol/L for composite sums) among children of ECHO-FGS participants ($n=618$) (numeric data in Table S12). Note: Multiple linear regression models adjusted for child’s urinary specific gravity, age (years), race/ethnic identity (NHB, Hispanic, NHW, or Asian/PI), sex assigned at birth (female/male), and body mass index (${\mathrm{kg}/\mathrm{m}}^2$), maternal education (completed secondary school yes or no), and season of urine collection (fall, winter, spring, or summer). We estimated the effect of membership in exposure category 1, 2, or 4 compared to exposure category 3 on the geometric mean urinary phthalate/replacement concentration (ng/mL or nmol/L for composite sums). The points on the graph represent the effect estimates for the relative differences in geometric mean concentrations, and the lines represent the 95% confidence intervals. CI, confidence interval; DEHP, diethylhexyl phthalate; DEHTP, di-2-ethylhexyl terephthalate; DINCH, di-isononyl cyclohexane-1,2-dicarboxylate; ECHO-FGS, Environmental Influences on Child Health Outcomes-Fetal Growth Study; LMW, low molecular weight; HMW, high molecular weight; MBP, mono-n-butyl phthalate; MBzP, mono-benzyl phthalate; MCiNP, mono-carboxy isononyl phthalate; MCiOP, mono-carboxy isooctyl phthalate; MCOCH, cyclohexane-1,2-dicarboxylic acid mono carboxyisooctyl ester; MCPP, mono (3-carboxypropyl) phthalate; MECPP, mono (2-ethyl-5-carboxypentyl) phthalate; MECPTP, mono-2-ethyl-5-carboxypentyl terephthalate; MEHHP, mono (2-ethyl-5-hydroxyhexyl) phthalate; MEHHTP, mono-2-ethyl-5-hydroxyhexyl terephthalate; MEHP, mono ethyl hexyl phthalate; MEOHP, mono (2-ethyl-5-oxohexyl) phthalate; MEP, monoethyl phthalate; MHNCH, cyclohexane-1,2-dicarboxylic acid mono hydroxyisononyl ester; MiBP, mono-isobutyl phthalate; MiNP, mono-isononyl phthalate; NHB, non-Hispanic black; NHW, non-Hispanic white; PI, Pacific Islander; SCP, skincare product.

Figure 2.

Relationships between SCP-use exposure profile categories and urinary phthalate/replacement metabolite concentrations (ng/mL or nmol/L for composite sums) among children of ECHO-FGS participants ($n=618$) (numeric data in Table S12). Note: Multiple linear regression models adjusted for child’s urinary specific gravity, age (years), race/ethnic identity (NHB, Hispanic, NHW, or Asian/PI), sex assigned at birth (female/male), and body mass index (${\mathrm{kg}/\mathrm{m}}^2$), maternal education (completed secondary school yes or no), and season of urine collection (fall, winter, spring, or summer). We estimated the effect of membership in exposure category 1, 2, or 4 compared to exposure category 3 on the geometric mean urinary phthalate/replacement concentration (ng/mL or nmol/L for composite sums). The points on the graph represent the effect estimates for the relative differences in geometric mean concentrations, and the lines represent the 95% confidence intervals. CI, confidence interval; DEHP, diethylhexyl phthalate; DEHTP, di-2-ethylhexyl terephthalate; DINCH, di-isononyl cyclohexane-1,2-dicarboxylate; ECHO-FGS, Environmental Influences on Child Health Outcomes-Fetal Growth Study; LMW, low molecular weight; HMW, high molecular weight; MBP, mono-n-butyl phthalate; MBzP, mono-benzyl phthalate; MCiNP, mono-carboxy isononyl phthalate; MCiOP, mono-carboxy isooctyl phthalate; MCOCH, cyclohexane-1,2-dicarboxylic acid mono carboxyisooctyl ester; MCPP, mono (3-carboxypropyl) phthalate; MECPP, mono (2-ethyl-5-carboxypentyl) phthalate; MECPTP, mono-2-ethyl-5-carboxypentyl terephthalate; MEHHP, mono (2-ethyl-5-hydroxyhexyl) phthalate; MEHHTP, mono-2-ethyl-5-hydroxyhexyl terephthalate; MEHP, mono ethyl hexyl phthalate; MEOHP, mono (2-ethyl-5-oxohexyl) phthalate; MEP, monoethyl phthalate; MHNCH, cyclohexane-1,2-dicarboxylic acid mono hydroxyisononyl ester; MiBP, mono-isobutyl phthalate; MiNP, mono-isononyl phthalate; NHB, non-Hispanic black; NHW, non-Hispanic white; PI, Pacific Islander; SCP, skincare product.