Members of the Depts. Community Medicine, Education, Geology, and Med. Statistics Unit, Univ. Edinburgh, have investigated the effect of blood-lead on cognitive ability and educational attainment in a sample of 855 boys and girls aged 6-9 years from 18 primary schools in central Edinburgh. The mean blood-lead level was 10.4 ug/dl. Multiple regression analyses of individual test scores showed a significant negative relation between blood-lead and British Ability Scales combined scores, number skills, and word reading, with 33 possible variables accounted for. The dose-response relation between blood-lead and test scores showed no evidence of a threshold or safe level. It was concluded that lead at low levels of exposure probably has a small harmful effect on the performance of children in cognitive ability and attainment tests. 
COMMENT: This finding is in agreement with that of a previous study in the USA  showing lead-related deficits in neuropsychological and classroom performance of children with elevated dentine lead levels. Exposure levels in the UK were lower than in the US study. Water and dust were the main sources of lead, attributed to a plumbosolvent water supply and lead plumbing in Edinburgh. Reports of research (1979-83) on the neuropsychological effects of lead in children are reviewed by the Medical Research Council, London, 1984.
A case of schizophrenic-like psychosis is an unusual manifestation of moderate lead intoxication (blood level of 60 ug/dl) reported in a 14 year old boy who had sniffed gasoline for 3 months. He was treated at Duke Univ Med Cntr, Durham, N Carolina, using a Ca EDTA challenge and 4 days chelation with dramatic clearing of agitation and psychotic symptoms. He had a history of dyslexia, visual-motor incoordination and conduct disorder. His IQ was 83 at 9 years of age and 69 on recovery from the lead intoxication. A possible psychobiological vulnerability to lead intoxication in children with learning problems, ADD, or mental retardation is proposed.