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The association between lead absorption and objective psychological performance tests in five groups with different levels of lead absorption was studied in the following groups: (1) a control, non-lead-exposed group; (2) cable splicers, (3) cable manufactures, and (4) secondary lead smelter workers. The following performance tests were used: Block Design, Digit Symbol, and Embedded Figures. Age-corrected performance test scores and the average of three test scores (INDEX) were used throughout. A significant association between performance tests scores and increased lead absorption was found. Zinc protoporphyrin level was a more "powerful" (in the statistical sense) indicator of lead-induced CNS effects than blood lead levels. This study provides additional evidence that neurotoxic effects associated with occupational exposure to lead can be demonstrated by means of performance tests. It has been known and widely accepted that increased lead absorption is associated with "non-specific" subjective symptoms: tiredness, sleep disturbance, irritability, etc. Psychometric techniques (including an appropriate statistical analysis strategy) are highly sensitive for the early detection of CNS neurotoxicity, such as metal toxicity. Moreover, even in lead-exposed but asymptomatic individuals, a significant correlation (negative) between test scores and levels of lead absorption could be detected. It is concluded that workers exposed to lead at levels considered "safe" might be at risk of developing brain dysfunction with long term exposure.

In a prospective study of lead neurotoxicity, exposed foundry workers and referents were evaluated using a comprehensive set of neurobehavioral tests. Other performance indexes were used including a questionnaire, physical examination, and nerve conduction testing. Results show increased rates of depression, confusion, anger, fatigue and tension among workers with blood levels over 40 mcg/dl. Other aspects of neurobehavioral function, including verbal concept formation, memory, and visual/motor performance were also impaired. In view of the large number of individuals exposed to lead in their work, specific inquiries should be made of individuals with affectual complaints to clarify the nature of their work and workplace exposure to lead.

Over 3,000 children attending first and second grade in public school were classified as to past lead exposure according to the concentrations of lead in their teeth. Those in the highest and lowest deciles for lead were evaluated by a broad panel of neuropsychologic outcome measures. Controlled either by matching or analysis of covariance were 39 other variables which could effect outcome. High lead children were significantly impaired on IQ auditory processing and reaction time under varying intervals of delay. Teacher's rating scales showed a dose-related increase in non-adaptive classroom behavior with no evidence of a threshold. EEG scores and observations of children in class demonstrated differences in high and low lead subjects.

Short forms of the WISC-R were computed by multiple linear regression on two samples of British children aged 6 to 12 years. The predictive validity of each short form was assessed both within the sample on which it was developed and cross-validated on the other sample. The empirically determined loss of power of prediction was found to be less than expected on a priori grounds. Predictions of individual scores at the lower end of the IQ distribution were less acceptable. It is concluded that short forms are robust and of value in research and for screening purposes, but cannot be recommended for clinical purposes.