Table 2.
Associations between prenatal exposure to a mixture of 6 phthalates and offspring Social Responsiveness Scale (SRS) total raw scores in HOME and EARLI: quantile g-computation models.
| Unadjusted modela | Adjusted model | ||||||
|---|---|---|---|---|---|---|---|
|
|
|
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| HOME (N=271) | EARLI (N=166) | Pooled (N=437) | HOMEb (N=271) | EARLIc (N=166) | Pooledd (N=437) | ||
| ψ1 (95% CI) | 1.3 (−0.35, 2.9) | −1.6 (−3.9, 0.65) | −0.36 (−1.8, 1.1) | 1.3 (−0.21, 2.8) | −0.88 (−3.5, 1.7) | 0.01 (−1.4, 1.5) | |
| Percentile | |||||||
| Minimum – 10th | −5.1 (−11, 1.4) | 6.6 (−2.6, 15) | 1.4 (−4.4, 7.3) | −5.1 (−11, 0.83) | 3.5 (−6.8, 13) | −0.03 (−5.8, 5.8) | |
| 10th – 20th | −3.8 (−8.7, 1.0) | 4.9 (−2.0, 11) | 1.1 (−3.3, 5.5) | −3.8 (−8.3, 0.62) | 2.6 (−5.1, 10) | −0.02 (−4.4, 4.3) | |
| 20th – 30th | −2.5 (−5.8, 0.69) | 3.3 (−1.3, 7.9) | 0.73 (−2.2, 3.7) | −2.6 (−5.5, 0.41) | 1.8 (−3.4, 6.9) | −0.01 (−2.9, 2.9) | |
| 30th – 40th | −1.3 (−2.9, 0.35) | 1.6 (−0.65, 3.9) | 0.36 (−1.1, 1.8) | −1.3 (−2.8, 0.21) | 0.88 (−1.7, 3.5) | −0.01 (−1.5, 1.4) | |
| 40th – 50th | Reference | Reference | Reference | Reference | Reference | Reference | |
| 50th – 60th | 1.3 (−0.35, 2.9) | −1.6 (−3.9, 0.65) | −0.36 (−1.8, 1.1) | 1.3 (−0.21, 2.8) | −0.88 (−3.5, 1.7) | 0.01 (−1.4, 1.5) | |
| 60th – 70th | 2.5 (−0.69, 5.8) | −3.3 (−7.9, 1.3) | −0.73 (−3.7, 2.2) | 2.6 (−0.41, 5.5) | −1.8 (−6.9, 3.4) | 0.01 (−2.9, 2.9) | |
| 70th – 80th | 3.8 (−1.0, 8.7) | −4.9 (−11, 2.0) | −1.1 (−5.5, 3.3) | 3.8 (−0.62, 8.3) | −2.6 (−10, 5.1) | 0.02 (−4.3, 4.4) | |
| 80th – 90th | 5.1 (−1.4, 11) | −6.6 (−16, 2.6) | −1.4 (−7.3, 4.4) | 5.1 (−0.83, 11) | −3.5 (−14, 6.8) | 0.03 (−5.8, 5.8) | |
| 90th – Maximum | 6.4 (−1.7, 14) | −8.2 (−20, 3.2) | −1.8 (−9.2, 5.5) | 6.4 (−1.0, 13) | −4.4 (−17, 8.4) | 0.04 (−7.2, 7.3) | |
Included di(2-ethylhexyl) phthalate (DEHP), mono-n-butyl phthalate (MBP), monobenzyl phthalate (MBzP), mono-3-carboxypropyl phthalate (MCPP), monoethyl phthalate (MEP), and mono-isobutyl phthalate (MiBP) as the independent variables. DEHP (ug/g creatinine) was calculated as ΣDEHP (ug/g creatinine) = [MEHP (ug/g creatinine)/278 (g/mol) + MEOHP (ug/g creatinine)/292 (g/mol) + MEHHP (ug/g creatinine)/294 (g/mol) + MECPP (ug/g creatinine)/308 (g/mol)] × 308 g/mol where 278, 292, 294, and 308 are the molecular weights of mono-2-ethylhexyl phthalate (MEHP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP), mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP), mono-2-ethyl-5-carboxypentyl phthalate (MECPP), respectively.
Included DEHP, MBP, MBzP, MCPP, MEP, MiBP, maternal age at delivery (years), three dummy variables for maternal race/ethnicity (Hispanic or Latino, Non-Hispanic black, Non-Hispanic white, Other/multiple races), maternal parity (0–2, >2), pre-pregnancy BMI (kg/m2), household annual income ($), child sex at birth (male, female), and child age at Social Responsiveness Scale (SRS) administration (months) as the independent variables.
Included DEHP, MBP, MBzP, MCPP, MEP, MiBP, maternal age at delivery (years), three dummy variables for maternal race/ethnicity (Hispanic or Latino, Non-Hispanic black, Non-Hispanic white, Other/multiple races), maternal parity (0–2, >2), pre-pregnancy BMI (kg/m2), household annual income ($), child sex at birth (male, female), child age at Social Responsiveness Scale (SRS) administration (months), and three dummy variables for study site (Drexel, Johns Hopkins University, Kaiser Permanente, UC Davis) as the independent variables.
Included DEHP, MBP, MBzP, MCPP, MEP, MiBP, maternal age at delivery (years), three dummy variables for maternal race/ethnicity (Hispanic or Latino, Non-Hispanic black, Non-Hispanic white, Other/multiple races), maternal parity (0–2, >2), pre-pregnancy BMI (kg/m2), household annual income ($), child sex at birth (male, female), child age at Social Responsiveness Scale (SRS) administration (months), and 4 dummy variables for study site (HOME, Drexel, Johns Hopkins University, Kaiser Permanente, UC Davis) as the independent variables.
All values are mean differences (95% confidence intervals [CIs]) for the pointwise comparisons between different percentiles as compared to the 40th percentile – 50th percentile unless otherwise specified. ψ1 (95% CI) represents the expected change in the SRS total scores, given a one quantile increase in all 6 phthalates simultaneously. All the phthalates were imputed with the lower limit of detection (LLOD) divided by a square root of two if lower than the LLOD and corrected for urinary dilution using urinary creatinine concentrations.
EARLI, the Early Autism Risk Longitudinal Investigation Study; HOME, the Health Outcomes and Measures of the Environment Study.