Evidence is presented showing that serial choice reaction performance is disrupted at low blood lead levels (PbB), and that parametric variation of task characteristics modulates the degree of disruption. This evidence is based on two independent studies in 6- to 9-year-old children living in two lead smelter areas in the cities of Nordenham (N = 114) and Stolberg (N = 109) in West Germany. Average PbB was 8.2 micrograms/100 ml (4.4-23.8 micrograms/100 ml) in the Nordenham sample and 7.4 micrograms/100 ml (4.2-18.0 micrograms/100 ml) in the Stolberg sample. Serial choice reaction performance was assessed by means of the Vienna reaction device in which a random sequence of light and tone signals has to be answered by pressing appropriate response buttons. Correct (hits) and false responses (errors) were evaluated as performance measures, and signal rate was varied in order to achieve easy and difficult task conditions. Exposure-related performance deficit was more pronounced for errors than for hits, more clearcut for high than for low signal rates, and proved significant in both studies after correction for confounding using confounder models of different complexities. Some features of the observed deficit resemble clinical observations in children presenting with attention deficit disorder.

Behavior↗

PubMedDate not supplied

Results from the European multicenter study on lead neurotoxicity in children: implications for risk assessment.

In order to improve dose-response information on neurobehavioral effects of environmental lead exposure in children, the World Health Organization, Regional Office for Europe (WHO/EURO), in collaboration with the Commission of the European Communities, initiated this international study which was planned, executed and evaluated between 1984 and 1989. Eight groups from eight European countries (Bulgaria, Denmark, Greece, Hungary, Italy, Roumania, W. Germany and Yugoslavia) took part. A common study protocol with inherent quality assurance elements was developed to achieve comparability. Blood-lead concentrations (PbB) were the main markers of exposure. The WISC (4 subtests) for psychometric intelligence, the Bender Gestalt test (GFT version) and the Trail-Making test for visual-motor integration, the Vienna Reaction Device and a delayed RT task for reaction performance, and the Needleman scales for behavior ratings served as behavioral endpoints. All individual studies taken together represent a sample size of 1879 school-age children and cover a PbB range from below 5 to about 60 micrograms/100 ml. Overall statistical evaluation of outcome was done by multiple regression analysis using a uniform confounder model. The strongest and most consistent effects occurred for the Bender Gestalt test (GFT version) and for serial choice reaction performance (Vienna Device). The degree of association with PbB was significant for these variables, although the contribution of PbB to the observed variance never exceeded 0.8%. Psychometric intelligence was also negatively affected, although the consistency of outcome between studies was poor, and the association with PbB only borderline. An effort towards risk assessment was made by calculating the proportion of children at risk, using the observed regression coefficients as well as means and standard deviations.

Child↗

PubMedDate not supplied

Pre- and postnatal lead-exposure in monkeys: effects on activity and learning set formation.

Rhesus monkeys were pre- and postnatally exposed to 0, 350, or 600 ppm lead acetate in the diet. Blood lead levels of the mothers were less than 1, 24.4, and 37.4 micrograms/100 g blood, respectively, while those of the offspring were substantially higher, at least in the early stages of development. At the age of 12-15 months the animals were tested for group activity levels in an unfamiliar environment. No substantial lead-related alterations of activity occurred neither for group activity nor for the activity of individual animals. There were, however significant dose-related impairments of pattern discrimination learning set formation, while in simple discrimination learning during the early training phases deficits were seen in the high lead group only. Emotional alterations of these animals may account for this result, whereas true cognitive deficits are likely to underly the impairment of learning set formation seen in the low lead group. It is concluded that the effects of lead in cognitive tasks are not secondary to changes of general activity level.

Animals↗

PubMedDate not supplied

[Correlative study of dust contents on the lungs and the changes of the bronchial walls in cases of sudden death].

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Bronchitis↗