Table 4.

Percent participation of cohort members in biologic sampling procedures in three birth cohort studies.^a

Study	Prenatal	6 months	12 months	24 months
University of California at Berkeley birth cohortc	n = 528	n = 473b	n = 442b	n = 422b
Home inspection/house dust	91	81	86	88d
Mount Sinai Medical Center IPM cohortc	n = 184	—	n = 112	n = 56
Air sample	100	—	100	100
Hand wipe	50	—	92	100
Toy wipe	75	—	96	100
Dust	96	—	100	100
Columbia University birth cohortc	n = 588
48-hr personal air	100	—	—	—
2-week integrated indoor air	17e	—	—	—
Kitchen dust samples	17e	—	—	—

^—, no samples collected at those time periods.

^aPercentages are calculated based on sample size provided for each study and time category; percent participation values are for participation in the environmental sampling procedures only and do not reflect retention rates for the cohorts.

^bPercent participation at 6, 12, and 24 months based on number of mothers participating rather than children due to several cases of twins.

^cBerkeley cohort (CHAMACOS) recruited in Salinas Valley, California (Eskenazi et al. 2003, 2004); Mount Sinai IPM cohort (Growing Up Health Integrated Pest Management Cohort, 1999–2002; Brenner et al. 2003); Columbia birth cohort (Whyatt et al. 2003).

^dPercentage permitting home visits at 24 months; no house dust collected.

^eCollected from a subset of 100 homes beginning during the 32nd week of pregnancy and continuing through delivery; kitchen dust samples are also collected from a subset of homes.