Characteristics of this sample of pregnant women are described in . Women were predominantly white or black non-Hispanic, never smokers, and had at least some college education. Phthalate concentrations with and without creatinine-adjustment are reported in . Urinary levels of MCHP, MINP, and MOP were below the limits of detection for all or nearly all women. Creatinine-adjusted phthalate distributions were log-normal except for MBP and MBZP; thus, results for these two metabolites are presented as medians rather than arithmetic means. Median phthalate levels reported in this study are comparable to U.S. population levels but lower than levels among pregnant women estimated by the National Health and Nutrition Examination Survey (NHANES) during a similar time period ().
Demographic characteristics of the 50 pregnant study participants, 2000–2004
Unadjusted and creatinine-adjusted urinary phthalate levels among 50 pregnant women1
Comparison of median creatinine-adjusted urinary phthalate levels (μ/g creatinine) to a U.S. population-based sample
Frequencies of product use reported on the 48-hour recall and mailed questionnaires and their associations with phthalate metabolites are reported in and , respectively. Products most commonly used by women in the past 48 hours were makeup and personal care items, particularly eye makeup, lipstick, and hand creams or lotions.
Frequencies of product use reported in the 48 hour recall questionnaire and associations with phthalate metabolites1
Frequencies of product use reported in the mailed questionnaire and associations with phthalate metabolites1
Women who reported using makeup most days of the week had higher levels of MBZP than women who did not (medians: 10.4 vs 5.2 μg/g creatinine, p=0.004). Use of eye shadow, eyeliner, or mascara in the past 48 hours was associated with higher levels of MBP (medians: 26.3 vs 12.8 μg/g creatinine, p=0.013), MBZP (medians: 7.9 vs 5.2 μg/g creatinine, p=0.034), MIBP (means: 3.7 vs 1.4 μg/g creatinine, p=0.022), and MEOHP (means: 23.6 vs 15.4 μg/g creatinine, p=0.045). Sunscreen use in the past 48 hours was associated with higher levels of MBP (medians: 50.7 vs 15.2 μg/g creatinine, p=0.024) and MMP (means: 3.2 vs 1.6 μg/g creatinine, p<0.001). Women who reported using bath oil, bath gel, or bubble bath in the past 48 hours had higher levels of MMP (means: 2.2 vs 1.5 μg/g creatinine, p=0.009). Using hair nutrient products in the past 48 hours was associated with increased urinary levels of MEP (means: 136.5 vs 124.7 μg/g creatinine, p=0.036) and MMP (means: 2.9 vs 1.6 μg/g creatinine, p=0.002). Women who applied or removed nail polish in the past 48 hours had statistically significantly higher levels of MBP (medians: 30.2 vs 15.1 μg/g creatinine, p=0.048) than women who were not exposed to nail polish. In contrast, urinary MEP concentrations were statistically significantly lower among women who applied or removed nail polish (means: 33.2 vs 138.7 μg/g creatinine, p=0.002).
Women who normally tried to buy fragrance-free products had lower levels of both MEHP (means: 6.8 vs 17.4 μg/g creatinine, p=0.037) and its secondary phthalate metabolite, MEHHP (means: 14.4 vs 37.6 μg/g creatinine, p=0.032). Use of cologne or perfume was associated with higher levels of MIBP (means: 3.6 vs 2.0 μg/g creatinine, p=0.011) and the DEHP metabolites MEHP (means: 17.2 vs 8.1 μg/g creatinine, p=0.007), MEHHP (means: 36.7 vs 18.1 μg/g creatinine, p=0.007), and MEOHP (means: 26.3 vs 13.8 μg/g creatinine, p=0.011).
Few women reported using household chemicals or cleaning products in the 48-hour recall questionnaire. In the mailed questionnaire, regular fabric softener use was associated with higher levels of MEP (means: 176.7 vs 95.0 μg/g creatinine, p=0.039). Air freshener use was associated with higher levels of MBP (medians: 23.9 vs 8.9 μg/g creatinine, p=0.015), MBZP (medians: 8.9 vs 3.5 μg/g creatinine, p=0.003), and MEP (means: 147.7 vs 70.7 μg/g creatinine, p=0.026).
With the exception of three items on the mailed questionnaire, housing characteristics and building materials were not associated with urinary metabolite levels. Women who lived in a building with two or more units had higher levels of MIBP (means: 4.7 vs 2.5 μg/g creatinine, p=0.018) than women who lived in a house. Women who had vinyl flooring in their places of residence had significantly lower levels of MEHP (means: 8.6 vs 22.0 μg/g creatinine, p=0.016). Paneling in the home was associated with higher levels of MEP (means: 201.4 vs 113.8 μg/g creatinine, p=0.026).
Eating deli or “to go” foods three or more times a week was not associated with phthalate levels in this group of women. Analyses could not be completed on IV treatments or chemical products such as paints and solvents because our sample of women did not report exposure to these items. There were no statistically significant associations between consumer products and MCPP, MEOHP, or MMP.
The results of our exploratory analysis of predictive ability of the questionnaire variables are presented in . The R2 values ranged between 0.31 for MEP and 0.42 for MMP. To a large extent, the predictors associated with each of the phthalates were personal care products, although different products were associated with different phthalates. While these models explained more variance than individual variables, there was no compelling pattern to the predictors identified. MMP had six products which overall explained 42% of the variance in creatinine adjusted MMP levels. Four of the products (sunscreen, bath oil, hair nutrient products, and hair styling gel) were positively associated with MMP, while two (spot cleaners and lipstick) were inversely associated. For MBP, seven items explained 39% of the variance and all were positively associated; four of these were personal care products used within the past two days and three where regular home activities within the past year (regular use of dryer sheets, air fresheners, and having interior walls painted).
Multiple linear regression results and proportion of variance explained (R2) for urinary phthalate metabolites and product use questionnaire items1