Effects of Great Lakes Fish Consumption on Brain PCB Pattern, Concentration, and Progressive-Ratio Performance

Self Cite

189

111

BackgroundSeveral epidemiologic studies have demonstrated relationships between prenatal exposure to polychlorinated biphenyls (PCBs) and modest cognitive impairments in infancy and early childhood. However, few studies have followed cohorts of exposed children long enough to examine the possible impact of prenatal PCB exposure on psychometric intelligence in later childhood. Of the few studies that have done so, one in the Great Lakes region of the United States reported impaired IQ in children prenatally exposed to PCBs, whereas another found no association.ObjectivesThis study was designed to determine whether environmental exposure to PCBs predicts lower IQ in school-age children in the Great Lakes region of the northeastern United States.MethodsWe measured prenatal exposure to PCBs and IQ at 9 years of age in 156 subjects from Oswego, New York. We also measured > 50 potential predictors of intelligence in children, including repeated measures of the home environment [Home Observation for Measurement of the Environment (HOME)], socioeconomic status (SES), parental IQ, alcohol/cigarette use, neonatal risk factors, and nutrition.ResultsFor each 1-ng/g (wet weight) increase in PCBs in placental tissue, Full Scale IQ dropped by three points (p = 0.02), and Verbal IQ dropped by four points (p = 0.003). The median PCB level was 1.50 ng/g, with a lower quartile of 1.00 ng/g and an upper quartile of 2.06 ng/g. Moreover, this association was significant after controlling for many potential confounders, including prenatal exposure to methylmercury, dichlorodiphenyldichloroethylene, hexachlorobenzene, and lead.ConclusionsThese results, in combination with similar results obtained from a similar study in the Great Lakes conducted 10 years earlier, indicate that prenatal PCB exposure in the Great Lakes region is associated with lower IQ in children.

Section: Methodssupporting

confidence: 85%

Section: Methodsmentioning

confidence: 99%

The Relationship between Prenatal PCB Exposure and Intelligence (IQ) in 9-Year-Old Children

Stewart

Lonky

Reihman

et al. 2008

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189

111

“…The mothers who did not stop eating fish throughout their pregnancies had the highest PCB isomer concentrations (Stewart et al 1999). Stewart et al (2000a) found a dose–response relationship between the prenatal exposure of the children to the highly chlorinated PCBs and increases in their reflexive and autonomic deviations from the norm and their reduced ability to habituate under various conditions. MRI examination of the most highly exposed children in this study revealed an inverse dose–response association between their PCB cord blood and the volume/size of the splenium of the corpus callosum at 7.8 years of age, and their response inhibition at 4.5 years of age, a behavioral characteristic seen in ADHD children where they do not adapt well to their environment and have trouble settling down (Stewart et al 2003).…”

Section: The Human Connectionmentioning

confidence: 93%

Neurodevelopment and Endocrine Disruption

Colborn¹

2004

234

134

In this article I explore the possibility that contaminants contribute to the increasing prevalence of attention deficit hyperactivity disorder, autism, and associated neurodevelopmental and behavioral problems in developed countries. I discuss the exquisite sensitivity of the embryo and fetus to thyroid disturbance and provide evidence of human in utero exposure to contaminants that can interfere with the thyroid. Because it may never be possible to link prenatal exposure to a specific chemical with neurodevelopmental damage in humans, I also present alternate models where associations have been made between exposure to specific chemicals or chemical classes and developmental difficulties in laboratory animals, wildlife, and humans.

“…The sampling methodology and demographic and exposure characteristics of this cohort have been previously published in detail (Lonky et al 1996; Stewart et al 1999, 2000a, 2000b). Of the 202 children available for testing, 195 had valid PCB exposure data, and 183 of these children completed the DRL task at 9.5 years of age.…”

Section: Methodsmentioning

confidence: 99%

“…Sample collection and analytic methods have been described elsewhere (Stewart et al 1999). Prenatal PCB exposure was assessed previously in terms of total cord PCBs (the sum of all 68 congeners and coeluters) and the sum of highly chlorinated PCB congeners (hepta-, octa-, and nonachlorinated biphenyl homologues; see Stewart et al 1999, 2000a). …”

Section: Methodsmentioning

confidence: 99%

Response Inhibition During Differential Reinforcement of Low Rates (DRL) Schedules May Be Sensitive to Low-Level Polychlorinated Biphenyl, Methylmercury, and Lead Exposure in Children

Stewart

Sargent

Reihman

et al. 2006

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BackgroundAnimal studies have shown that exposure to common, low-level environmental contaminants [e.g., polychlorinated biphenyls (PCBs), lead] causes excessive and inappropriate responding on intermittent reinforcement schedules. The Differential Reinforcement of Low Rates task (DRL) has been shown to be especially sensitive to low-level PCB exposure in monkeys.ObjectivesWe investigated the relationships between prenatal PCB and postnatal Pb exposure performance on a DRL schedule in children. We predicted that a) prenatal PCB exposure would reduce interresponse times (IRTs) and reinforcements earned, and b) postnatal Pb exposure would reduce IRTs and reinforcements earned.MethodsWe tested 167 children on a DRL20 (20 sec) reinforcement schedule, and recorded IRTs and the number of reinforced responses across the session. We measured prenatal PCB exposure (cord blood), methylmercury (MeHg) (maternal hair), and postnatal Pb exposure (venous blood), and > 50 potentially confounding variables.ResultsResults indicated impaired performance in children exposed to PCBs, MeHg, and Pb. Children prenatally exposed to PCBs responded excessively, with significantly lower IRTs and fewer reinforcers earned across the session. In addition, exposure to either MeHg or Pb predicted statistically significant impairments of a similar magnitude to those for PCBs, and the associated impairments of all three contaminants (PCB, MeHg, and Pb) were statistically independent of one another.ConclusionsThese results, taken with animal literature, argue the high sensitivity of DRL performance to low-level PCB, MeHg, and Pb exposure. Future research should employ behavioral tasks in children, such as DRL, that have been demonstrably sensitive to low-level PCB, MeHg, and Pb exposure in animals.