A biomarker validation study of prenatal chlorpyrifos exposure within an inner-city cohort during pregnancy.
BACKGROUND
We previously documented significant decreases in chlorpyrifos concentrations in maternal personal and indoor air samples among pregnant African-American and Dominican women from New York City after the 2000-2001 restrictions on its residential use.


OBJECTIVE
We undertook a biomarker validation study within the same cohort to evaluate trends over time in multiple biomarkers of prenatal chlorpyrifos exposure.


METHODS
Subjects were enrolled between February 2001 and May 2004 (n = 102). We measured 3,5,6-trichloro-2-pyridinol (TCPy) in postpartum meconium (n = 83), repeat prenatal maternal spot urine samples (n = 253), and postnatal urine from the mothers (n = 73) and newborns (n = 59). We measured chlorpyrifos in postnatal maternal (n = 92) and umbilical cord (n = 65) blood.


RESULTS
We did not detect TCPy in infant urine, but all other biomarkers showed a highly significant decrease in detection frequencies (chi2 = 7.8-34.0, p < or = 0.005) and mean ranks (p < or = 0.006, Kruskal-Wallis) among subjects enrolled in 2003-2004 compared with those enrolled in 2001-2002. Chlorpyrifos in maternal personal and indoor air declined 2- to 3-fold over the same period (p < 0.05). In 2001-2002 samples, TCPy levels in repeat prenatal urine were positively correlated (r = 0.23-0.56), but within-subject variability exceeded between-subject variability (intraclass correlation coefficient = 0.43); indoor air levels explained 19% of the variance in prenatal urine TCPy (p = 0.001). Meconium TCPy concentrations were positively correlated with chlorpyrifos in maternal and cord blood (r = 0.25-0.33, p < 0.05) and with TCPy in maternal urine (r = 0.31, p < 0.01).


CONCLUSIONS
Results suggest the biomarkers are reliable dosimeters to differentiate between groups with prenatal chlorpyrifos exposures varying by a factor of 2 or more and vividly illustrate the efficacy of residential restriction on chlorpyrifos to reduce the internal dose during pregnancy.
Columbia Center for Children's Environmental Health, Department of Environmental Health Sciences, Joseph L. Mailman School of Public Health, Columbia University, New York, New York 10032, USA. rmw5@columbia.edu
Robin M
RM
Whyatt
Robin
R
Garfinkel
Lori A
LA
Hoepner
Howard
H
Andrews
Darrell
D
Holmes
Megan K
MK
Williams
Andria
A
Reyes
Diurka
D
Diaz
Frederica P
FP
Perera
David E
DE
Camann
Dana B
DB
Barr
D015415:Biomarkers / Q000097:blood / Q000652:urine; D004390:Chlorpyrifos / Q000032:analysis* / Q000097:blood / Q000652:urine; D003710:Demography; D004784:Environmental Monitoring; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007306:Insecticides / Q000032:analysis* / Q000097:blood / Q000652:urine; D018811:Maternal Exposure; D008470:Meconium / Q000737:chemistry; D011247:Pregnancy; D011728:Pyridones / Q000652:urine; D014505:Urban Population / Q000706:statistics & numerical data
D015415:Biomarkers; D007306:Insecticides; D011728:Pyridones; C012587:3,5,6-trichloro-2-pyridinol; D004390:Chlorpyrifos