Academic journal article Environmental Health Perspectives

A Biomarker Validation Study of Prenatal Chlorpyrifos Exposure within an Inner-City Cohort during Pregnancy

Academic journal article Environmental Health Perspectives

A Biomarker Validation Study of Prenatal Chlorpyrifos Exposure within an Inner-City Cohort during Pregnancy

Article excerpt

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 ([chi].sup.2] = 7.8-34.0, p [less than or equal to]; 0.005) and mean ranks (p [less than or equal to] 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.

KEY WORDS: biomarkers, chlorpyrifos, cord blood, indoor air, maternal blood, meconium, pregnancy, urine. Environ Health Perspect 117:559-567 (2009). doi:10.1289/ehp.080004l available via http://dx.doi.org/[Online 5 December 2008]

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Residential pesticide use is widespread in the United States. Eighty-five percent of American households store at least one pesticide in their home, and approximately 10% of the mass of conventional pesticides used annually in the United States are applied in and around the home (Adgate et al. 2000; Kiely et al. 2004). Until its use was restricted, chlorpyrifos was one of the most widely used insecticides for residential pest control. Use was particularly heavy in New York City. During 1997, the amount of the insecticide applied by licensed applications in New York City exceeded the amount applied in any other county in New York State, including agricultural communities (Thier 1998). In June 2000, the U.S. Environmental Protection Agency (EPA) entered into an agreement with the registrant to begin phasing out residential chlorpyrifos uses and to terminate all retail sales for indoor use by December 2001 (U.S. EPA 2000). Chlorpyrifos is still widly used in agriculture, with approximately 10 million pounds applied annually in the United States; use on corn constitutes the largest market share (U.S. EPA 2002).

We have previously reported on chlor pyrifos concentrations in personal and indoor air samples among a cohort of 102 women residing in inner-city communities within New York City (Whyatt et al. 2007). Chlorpyrifos was detected in 99% of 48-hr maternal personal air samples during the 32nd week of pregnancy and in 99.7% of 2-week integrated indoor air samples collected sequentially from the 32nd week of pregnancy until delivery. There was little within-home variability in indoor air levels; between-home variability accounted for 92% of the variance in chlorpyrifos air concentrations. …

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