Academic journal article Environmental Health Perspectives

Prenatal Exposure to Organophosphorous Pesticides and Fetal Growth: Pooled Results from Four Longitudinal Birth Cohort Studies

Academic journal article Environmental Health Perspectives

Prenatal Exposure to Organophosphorous Pesticides and Fetal Growth: Pooled Results from Four Longitudinal Birth Cohort Studies

Article excerpt

Introduction

Organophosphorous (OP) pesticides, a widely used class of insecticides, have been the subject of concern in recent years because of their potential for developmental and neurobehavioral toxicity (Bouchard et al. 2011; Engel et al. 2011; Rauh et al. 2011). Two common OP pesticides, chlorpyrifos and diazinon, were removed from residential pesticide use between 2001 and 2004, largely due to concerns about effects on health (U.S. EPA 2001); however, applications in agriculture continue. Although use of OP pesticides has declined substantially in recent years, they still accounted for 35% of insecticides applied in the United States in 2007, the latest year for which data are available (Grube et al. 2011).

Several OP pesticides have been associated with reduced fetal growth in rodent studies (Breslin et al. 1996; Qiao et al. 2002; Spyker and Avery 1977; Srivastava and Raizada 1996), but studies in humans are inconsistent. Two studies have examined maternal or fetal blood concentrations of OP pesticides (Barr et al. 2010; Whyatt et al. 2004), and four studies have looked at maternal urinary concentrations of OP metabolites (Eskenazi et al. 2004; Rauch et al. 2012; Wang et al. 2012; Wolff et al. 2007). Chlorpyrifos concentrations in umbilical cord blood were inversely associated with birth weight and length in a population of low-income, African-American and Dominican women in New York City recruited before the household ban (Columbia cohort) (Whyatt et al. 2004). However, a similar study conducted after the ban found no associations with birth outcome among pregnant women in New Jersey whose chlorpyrifos concentrations were considerably lower than the Columbia study (Barr et al. 2010). Dialkyl phosphate (DAP) metabolites of OP pesticides in maternal urine were inversely associated with infant head circumference but not birth weight or length in a racially and economically diverse population of women in New York City (Mount Sinai cohort) (Wolff et al. 2007). Prenatal urinary DAP metabolites were associated with shorter length of gestation and nonsignificantly increased birth weight, length, and head circumference in a cohort of low-income predominantly Mexican women in California (Center for the Health Assessment of Mothers and Children of Salinas; CHAMACOS cohort) (Eskenazi et al. 2004). A study of pregnant women in Cincinnati, Ohio (Health Outcomes and Measures of the Environment; HOME study) found that prenatal urinary DAPs were associated with decreased birth weight in African-American mothers and shorter length of gestation in white mothers (Rauch et al. 2012). However, a study in Shanghai, China, found no association between maternal urinary DAPs at time of labor and birth weight or length (Wang et al. 2012).

Inconsistencies in these findings may be attributable to differences in timing of exposure (e.g., early vs. late pregnancy), measurement of OP exposure (e.g., parent compounds in blood vs. nonspecific DAP metabolites in urine), variability in OP mixtures (e.g., chlorpyrifos or diazinon used residentially vs. a wider range of OP compounds used in agriculture), and patterns of exposure (residential vs. agricultural vs. dietary exposure) across studies. Other challenges to integrating these disparate results include the diverse racial/ethnic compositions of these cohorts, which contribute to differing frequencies of key genetic modifiers, among other sources of heightened susceptibility. For example, paraoxonase (PON) is an enzyme that plays a key role in metabolism and detoxification of some OP pesticides (Costa et al. 2008). Paraoxonase levels and efficiency are influenced by several common single nucleotide polymorphisms (SNPs) in the PON1 gene whose allele frequencies vary significantly in different racial groups (Costa et al. 2003). SNPs at the -108 position in the promoter region of the PON1 gene appear to influence an individual's quantity of the paraoxonase enzyme (subjects with [PON1. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.