Relationship between blood lead concentrations and learning achievement among primary school children in Taiwan

Over the past 20 years lead has been proven to exert an influence on the intelligence of children. Especially for children exposed to environmental lead, average blood lead was often lower than the officially recognized intoxication level. Because Kaohsiung is an industrial area in Taiwan and lead exposure is an important environmental issue, we attempted to ascertain the extent to which environmental lead influences the achievement of primary school children. We randomly selected 934 children from 32 primary schools in 11 districts of Kaohsiung City. Blood lead levels of the children were checked, and they were administered a questionnaire about their family information. Scores of several courses were used in this study on the relationship between a child's blood lead and his or her academic performance (Ranking with his or her classmates), including Chinese (reading and writing short Chinese articles), Mathematics, History and Society, and Natural Science. Multiple regression models were done with adjustments for the confounding effects of their parents' socioeconomic levels. The mean (SD) of 934 blood lead level was 5.50 (1.86) microg/dL. Spearman's coefficient showed that class rankings in Chinese, Mathematics, Natural Science, and History and Society were all strongly associated with blood lead levels (P<0.01). The multiple regression models revealed that blood lead level exerts a stronger influence on children's language ability (Chinese) than on their ability to calculate (Mathematics). Our results suggest that environmental lead exposure adversely affects a child's academic achievement, making a direct link between exposure to lead and academic attainment.