Main and Interaction Effects of Metallic Pollutants on Cognitive Functioning

Abstract

The present study investigated possible relationships of metal levels and metal combinations with children's cognitive functioning. Hair-metal concentrations of lead, arsenic, mercury, cadmium, and aluminum were determined in 69 randomly selected elementary age children. They were also administered the Wide Range Achievement Test reading and spelling tests and the Bender Visual-Motor Gestalt Test. Parents of subjects were interviewed to control for confounding variables that may affect cognitive development. Regression data indicated that increases in arsenic and the interaction of arsenic with lead were significantly related to decreased reading and spelling achievement, and increases in aluminum and the interaction of aluminum with lead were significantly related to decreased visual-motor performance. A continuing reexamination of metal poisoning concentrations is needed, because metal levels and metal combinations previously thought harmless may be associated with cognitive deficits. I t is well established that children exposed to high doses of lead and other metal pollutants are often left with permanent neurological sequelae and with mental impairment. A source of considerable debate, however, is whether low doses of metals adversely affect cognitive functioning (Rutter, 1980). Although limited by methodological errors, previous studies have linked low lead levels with cognitive, perceptual, and behavior deficits (Needleman et al., 1979;Winneke et al., 1983; Yule et al., 1982). Among the methodological errors of earlier studies is the failure to account for the influence of other toxic metals on lead-dose behavioral response measures. Although largely unexplored, low levels of arsenic, cadmium, mercury, and aluminum have been recently linked to childhood developmental decrements (Marlowe et al., 1983a;Marlowe et al., 1983b;Thatcher et al., 1982), and some investigators have hypothesized that metal combinations may have an interactive effect, thereby increasing the total toxicity of the child's system.The purpose of this study was to deal with the above design issues while measuring the relationships between lead and other individual metal levels and metal combinations and children's performance on tests measuring reading and spelling achievement and visual-motor performance. It was hypothesized that as children's individual metal levels and metal combinations increased, their cognitive performance would decrease.

Postnatal Cadmium Exposure, Neurodevelopment, and Blood Pressure in Children at 2, 5, and 7 Years of Age

“…In a cohort study, the concentration of cadmium was inversely related to IQ (Thatcher et al 1982). Other investigators reported associations between cadmium and children’s performance on verbal IQ and visual-motor and cognitive tasks (ATSDR 1999; Marlowe et al 1985b; Moon et al 1985). However, these studies have received little attention, and it is not clear whether the effects described were due to exposure to cadmium or to other substances (i.e., lead exposure).…”

Probabilistic Integrated Human Mixture Risk Assessment of Multiple Metals Through Seafood Consumption

“…According to the ATSDR's interaction profiles (ATSDR, , ), the interaction of iAs–Cd–Pb–MeHg for neurological effects may be greater than additive; this observation is mainly based on two findings in children concerning (i) a potentiating interaction of Pb on As‐associated decreases in reading and spelling (Moon, Marlowe, Stellern, & Errera, ) and (ii) the potentiating effects of As or Cd alone on Pb‐induced maladaptive classroom behavior (Marlowe et al., ). Regarding the mechanism of toxicity, both As and Pb react with the sulfhydryl groups of proteins and alter mitochondrial functions, whereas both Cd and Pb inhibit calcium entry into neurons (ATSDR, ).…”

Hair minerals and diet of Prader-Willi syndrome youth

“…These data support other recent studies that have correlated increased hair metal levels with mental retardation (Marlowe, Folio, Hall, & Errera, 1982;Marlowe, Errera, & Jacobs, 1983). Studies of general school populations have also linked increasing hair metal levels and their interactions to decrements in psychometric intelligence (Thatcher, Lester, McAlaster, & Horst, 1982;Moon, Marlowe, & Errera, in press), adaptive behavior (Marlowe, Cossairt, Moon, & Errera, 1985), and academic achievement (Moon, Marlowe, Stellern, & Errera, 1985).…”