Correcting for the influence of sampling conditions on biomarkers of exposure to phenols and phthalates: a 2-step standardization method based on regression residuals

Mortamais, Marion; Chevrier, Cécile; Philippat, Claire; Petit, Claire; Calafat, Antonia M; Ye, Xiaoyun; Silva, Manori J; Brambilla, Christian; Eijkemans, Marinus JC; Charles, Marie-Aline; Cordier, Sylvaine; Slama, Rémy

doi:10.1186/1476-069X-11-29

Environmental Health

Table 2 Adjusted Association Between Log-Transformed Phthalate Monoester Metabolites Urinary Concentrations and Sampling Conditions among French Pregnant Women From Eden and Pélagie Cohorts, 2002 – 2006 ^a

From: Correcting for the influence of sampling conditions on biomarkers of exposure to phenols and phthalates: a 2-step standardization method based on regression residuals

		DEHP metabolitesh^h			MiBP		MBP		MCPP		MBzP		MEP		MCNP		MCOP
Sampling conditions	n	β	P, p trend	β	P, p trend	β	P, p trend	β	P, p trend	β	P, p trend	β	P, p trend	β	P, p trend	β	P, p trend
Hour of sampling	191		.02^f, > .01^g		.29 ^f, .08^g		> 0.01^{f ,g}		.04 ^f, .03^g		.06 ^f, .13^g		.66 ^f, .71^g		.12 ^f, .22^g		.32 ^f, .16^g
> 7.00 AM	36	0		0		0		0		0		0		0		0
7.00 to 7.59 AM	75	0.00	0.99	− 0.18	0.44	− 0.29	0.22	0.04	0.86	0.33	0.28	− 0.29	0.24	0.26	0.30	0.08	0.73
8.00 to 9.59 AM	59	− 0.39	0.09	− 0.27	0.31	− 0.51	0.05	− 0.08	0.71	− 0.09	0.78	− 0.21	0.46	− 0.16	0.58	− 0.20	0.39
After 10.00 AM	21	− 0.80	0.03	− 0.63	0.06	− 1.08	> 0.01	− 0.88	> 0.01	− 0.68	0.09	− 0.11	0.77	− 0.53	0.29	− 0.39	0.23
Continuous ^b		− 0.09	0.04	− 0.06	0.22	− 0.20	> 0.01	− 0.10	0.02	− 0.09	0.09	− 0.03	0.62	− 0.12	0.05	− 0.09	0.05
Creatinine(g/l)^c	287	1.1	> 0.01	0.98	> 0.01	0.96	> 0.01	0.95	> 0.01	1.2	> 0.01	0.96	> 0.01	0.76	> 0.01	0.91	> 0.01
Gestational age (weeks)
Pélagie cohort	96		.92 ^f, .56^g		.61 ^f, .34^g		.74 ^f, .52^g		.02 ^f, .52^g		.28 ^f, .24^g		.23 ^f, .47^g		.29 ^f, .11^g		.48 ^f, .36^g
6-10	24	0		0		0		0		0		0		0		0
10-12	20	0.03	0.94	− 0.009	0.98	0.16	0.60	0.82	0.01	− 0.27	0.45	− 0.26	0.56	− 0.24	0.47	0.31	0.42
12-14	41	0.06	0.84	0.37	0.29	0.33	0.28	0.21	0.48	0.26	0.44	0.35	0.27	− 0.29	0.38	− 0.10	0.78
14-19	11	0.29	0.56	0.10	0.75	0.06	0.87	− 0.04	0.91	0.22	0.63	− 0.20	0.60	− 0.76	0.07	− 0.20	0.62
Continuous ^d		− 0.01	0.76	0.02	0.67	0.01	0.74	− 0.008	0.84	0.05	0.36	0.03	0.54	− 0.07	0.17	− 0.04	0.42
Eden cohort	191		.50 ^f, .30^g		.25 ^f, .58^g		.14 ^f, .09^g		.18 ^f, .08^g		.01 ^f, .43^g		.67 ^f, .95^g		.15 ^f, .36^g		.63 ^f, .38^g
24-25	25	0		0		0		0		0		0		0		0
25-27	87	− 0.06	0.75	− 0.27	0.23	0.01	0.97	0.05	0.82	− 0.58	0.03	− 0.22	0.44	− 0.20	0.57	− 0.02	0.94
27-30	79	0.13	0.48	− 0.01	0.96	0.38	0.21	0.33	0.14	− 0.06	0.84	− 0.10	0.74	0.15	0.68	0.14	0.49
Continuous ^d		0.03	0.55	0.04	0.50	0.14	0.04	0.11	0.07	0.07	0.35	− 0.007	0.93	0.07	0.35	0.02	0.79
Day of sampling	287		0.31 ^f		0.40 ^f		0.96 ^f		0.61 ^f		0.18 ^f		0.11 ^f		0.05 ^f		0.44 ^f
Monday	57	0		0		0		0		0		0		0		0
Tuesday	69	− 0.37	0.14	− 0.17	0.42	0.04	0.86	− 0.11	0.54	0.02	0.93	− 0.02	0.92	− 0.29	0.19	− 0.20	0.33
Wednesday	65	− 0.10	0.64	− 0.27	0.11	− 0.0005	0.99	− 0.24	0.20	− 0.06	0.81	− 0.04	0.88	− 0.45	0.02	− 0.39	0.03
Thursday	48	− 0.33	0.13	− 0.18	0.39	− 0.14	0.49	− 0.36	0.11	− 0.11	0.60	− 0.22	0.36	− 0.10	0.73	− 0.30	0.17
Friday	34	− 0.28	0.25	− 0.40	0.04	0.14	0.61	− 0.10	0.73	− 0.53	0.04	− 0.25	0.38	− 0.45	0.02	− 0.47	0.08
Saturday	7	− 0.41	0.17	− 0.04	0.88	0.05	0.85	− 0.42	0.19	0.06	0.85	− 0.92	> 0.01	− 0.63	0.03	− 0.57	0.16
Sunday	7	0.17	0.46	0.17	0.64	− 0.19	0.57	− 0.40	0.21	0.42	0.22	− 0.47	0.20	− 0.18	0.48	− 0.38	0.22
Season of sampling	287		0.54 ^f		0.34 ^f		0.92 ^f		0.86 ^f		0.52 ^f		0.84 ^f		0.81 ^f		0.98 ^f
Jan-March	83	0		0		0		0		0		0		0		0
April-June	80	− 0.05	0.79	− 0.12	0.49	0.08	0.65	− 0.10	0.55	− 0.06	0.75	− 0.12	0.56	0.005	0.98	0.07	0.70
July-Sept	59	− 0.15	0.47	− 0.12	0.57	− 0.004	0.98	− 0.07	0.71	0.21	0.35	0.06	0.82	0.10	0.63	0.06	0.79
Oct-Dec	65	− 0.33	0.15	− 0.38	0.07	0.12	0.62	− 0.17	0.42	− 0.17	0.52	− 0.07	0.76	− 0.10	0.65	0.03	0.90
Duration of urine storage at room temperature (hours)	287		.29 ^f, .30^g		.38 ^f, .29^g		.82 ^f, .66^g		.83 ^f, .58^g		.30 ^f, .27^g		.51 ^f, .95^g		.85 ^f, .97^g		.24 ^f, .38^g
≤ 3	57	0		0		0		0		0		0		0		0
3-5	84	− 0.22	0.33	0.29	0.18	0.23	0.34	0.09	0.63	− 0.006	0.99	0.18	0.49	− 0.22	0.43	− 0.12	0.58
6-24	94	− 0.01	0.96	0.13	0.58	0.16	0.57	0.21	0.36	− 0.09	0.80	− 0.21	0.57	− 0.20	0.57	− 0.23	0.39
> 24	52	− 0.35	0.34	0.35	0.26	0.19	0.60	0.20	0.51	0.39	0.38	0.0005	0.99	− 0.05	0.91	0.21	0.55
Continuous ^e		− 0.002	0.11	− 0.002	0.21	− 0.002	0.05	0.0003	0.86	0.0007	0.69	0.0004	0.81	− 0.001	0.36	0.001	0.43

We applied correction factors of 0.66 and 0.72 to the monoethyl phthalate (MEP) and monobenzyl phthalate (MBzP) concentrations, respectively, because the analytic standards used were of inadequate purity.
^a Linear regression models were corrected for over-representation of cases and adjusted for maternal age, BMI, parity, centre, education, occupation and urine sampling conditions.
^b Regression parameters are given for an increase by 1 in the sampling hour.
^c Regression parameters are given for an increase by 1 g/l in urinary creatinine concentration.
^d Regression parameters are given for an increase by 1 week.
^e Regression parameters are given for an increase by 1 hour.
^f P of heterogeneity test.
^g P of trend test based on the indicated categories.
^h DEHP metabolites: MEHHP + MEOHP + MECPP + MEHP.

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ISSN: 1476-069X

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