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6 Neurologic Effects
Pages 171-185

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From page 171...
... Impaired learning and altered activity levels, such as increases in the reactivity to aversive events, were observed in rats fed a 30% diet of Lake Ontario salmon, which are contaminated 171
From page 172...
... This highlights the complexity of the problem of teasing apart neurobehavioral and neurodevelopmental effects and mechanisms for cognitive functioning. HUMAN STUDIES Neurobehavioral effects of exposure to PCBs and other chemicals that might act as HAAs have been studied extensively in four human populations, and studies are continuing in three other populations (Table 6-1~.
From page 173...
... 1992~. The Japanese and Taiwanese studies demonstrate developmental delays and cognitive defects in young children prenatally exposed to PCBs and other products of heat-degraded PCBs.
From page 175...
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From page 176...
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From page 177...
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From page 178...
... Preference for novelty decreased in a dose-dependent fashion with increasing prenatal PCB exposure, although postnatal exposure was not related. The effect of PCB exposure on recognition memory in newborns was not mediated by smaller body size or by behavioral deficits associated with PCB exposure; infants performing poorly at 7 mo had not necessarily exhibited deficits at birth (Jacobson et al.
From page 179...
... The IQ score of the most highly exposed group (1.25 ,ug/g breast milk, 4.7 ng in cord serum, or 9.7 ng in maternal serum) averaged 6.2 points lower than the other four groups after adjusting for potential confounders, including socioeconomic status, maternal age, age at testing, delivery complications, maternal drinking and smoking, parity, and number of children in household (p = .007~.
From page 180...
... . Neither postnatal PCB exposure nor postnatal DDE exposure was related to either score at 6 or 12 mo, nor was the PDI related to prenatal DDE concentrations.
From page 181...
... Oswego, New York An ongoing prospective longitudinal study has been designed to examine the behavioral effects of maternal consumption of Lake Ontario fish that contained a range of persistent chemicals, including PCBs, hexachlorobenzene (HCB) , polychlorinated dibenzo-p-dioxin (PCDD)
From page 182...
... at 3.5 yr. Prenatal exposure to PCBs was measured using maternal and umbilical cord plasma samples, postnatal exposure to PCBs and dioxins was measured using breast-milk samples, and current exposure to PCBs was determined in the child's plasma.
From page 183...
... Children were evaluated using the Bayley scales of infant development (BSID) , psychomotor development tests, and the Fagan visual recognition memory test at 7 mot Mean concentrations of PCBs were 0.55 ng/mL in cord blood and 427 ng/g in the fat of breast milk.
From page 184...
... For example, one study measuring psychomotor development at 18 mo with the Neurologic Examination for Toddler-Age found a significant reduction in necrologic function in prenatally exposed children (Huisman et al.
From page 185...
... NEUROLOGIC EFFECTS 185 RECOMMENDATIONS The majority of the data reviewed by the committee on the necrologic effects of HAAs focused on only a few chemicals, namely PCBs, PCDF, dioxin, and DDT. Based on the committee's evaluation of those data, the following are recommended: Human populations suspected of being affected by HAAs should continue to be monitored for adverse necrologic effects.


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