In Utero Exposure to Background Levels of Polychlorinated Biphenyls and Cognitive Functioning among School-age Children

Abstract

Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants. In utero exposure to background levels of PCBs has been associated with intellectual impairment among children in most, but not all, studies. The authors evaluated prenatal PCB exposure in relation to cognitive test (intelligence quotient (IQ)) scores on the Wechsler Intelligence Scale for Children at age 7 years. Pregnant women were recruited from 12 US study centers from 1959 to 1965, and their children were followed until age 7 years (the Collaborative Perinatal Project). Third trimester serum was analyzed for PCBs in 1997-1999 for 732 women selected at random and for an additional 162 women whose children had either a low or a high IQ score. The PCB-IQ association was examined in multivariate models. Among those in the lowest exposure category (<1.25 microg of PCB/liter of serum), the fully adjusted mean IQ score was 93.6 (standard error: 1.8); among those in the highest category (> or =5 microg of PCB/liter), the mean IQ was 97.6 (standard error: 1.2); and overall the increase in IQ per unit increase in PCB level (microg/liter) was 0.22 (95% confidence interval: -0.28, 0.71). In these data, in utero exposure to background levels of PCBs was not associated with lower IQ at age 7 years.

Childhood IQ, hearing loss, and maternal thyroid autoimmunity in the Baltimore Collaborative Perinatal Project

“…Lead exposure was a public health concern in Baltimore during the 1960s and 1970s and even blood lead concentrations of <10 µg/ dl have been implicated in poorer cognitive performance (16). Nevertheless, the mean IQ in this study is consistent with averages observed in a study of nationwide CPP data (17,18).…”

Estimating perchlorate exposure from food and tap water based on US biomonitoring and occurrence data

“…environmental exposure has been reported to be associated with altered psychomotor development in children and lower birth weight and size in newborns ( Hertz-Picciotto et al, 2005;Koopman-Essenboom et al, 1996;Sagiv et al, 2007;Sala et al, 2001), although other studies have either not confirmed these findings or found that such effects do not persist into toddler and school aged children (Gladen and Rogan, 1991;Gray et al, 2005;Hertz-Picciotto et al, 2005;Koopman-Essenboom et al, 1996;Wolff et al, 2007). Many animal studies demonstrate that high dose PCB impairs neurodevelopment or their hydroxylated metabolites may interfere with thyroid hormone-dependent neurodevelopment (Kimura-Kuroda et al, 2007;Nguon et al, 2005;Purkey et al, 2004;Roegge et al, 2006).…”

Upstream adverse effects in risk assessment: A model of polychlorinated biphenyls, thyroid hormone disruption and neurological outcomes in humans

“…Relationship 3: prenatal PCB body burdens and neurocognitive outcomes We found 8 studies that directly assessed maternal PCB body burdens and cognitive outcomes in children (Gray et al, 2005;Jacobson, 1996, 2003;Jacobson et al, 1990;Patandin et al, 1999;Stewart et al, 2008;Vreugdenhil et al, 2002;Stewart et al, 2003) (see Table 3). Five met our inclusion criteria (Gray et al, 2005;Jacobson et al, 1990;Patandin et al, 1999;Stewart et al, 2008;Vreugdenhil et al, 2002).…”

“…We obtained a slope for the relationship between FT 4 and IQ in Haddow et al (1999) by simulating the population distribution of FT4 and IQ in case and control groups (see Supplementary Material for more Jacobson et al (1990), and Vreugdenhil et al (2002) used models with a log-transformed sum of PCB concentration as the independent variable. Gray et al (2005) and Stewart et al (2008) used linear models. We converted their slopes using log-transformed PCBs as the independent variable.…”