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.
Whyatt
Robin M
RM
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
Garfinkel
Robin
R
Hoepner
Lori A
LA
Andrews
Howard
H
Holmes
Darrell
D
Williams
Megan K
MK
Reyes
Andria
A
Diaz
Diurka
D
Perera
Frederica P
FP
Camann
David E
DE
Barr
Dana B
DB
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