[Effects of manganese on learning abilities in school children]

Manganese in drinking water of Wu Village, Qingchu County, Taiyuan, Shanxi Province persisted in an excessive level all the year round, hair and blood manganese contents in its primary school pupils, averaged 1.242 micrograms/g and 617 nmol/L (3.39 micrograms/dl), respectively, were higher than those in normal children, and the school records of the former were poorer than those of the latter. Levels of serum 5-hydroxytryptamine (5-HT), dopamine, norepinephrine and acetylcholine esterase of those 92 school children were determined to study their relationship with poor learning abilities. Results showed levels of four neurotransmitter in them all were lower than those in control children. School records for Chinese language and mathematics correlated positively to the levels of most neurotransmitter. Multiple linear regression analysis showed the order of the effects of neurotransmitter on school records of Chinese language was 5-HT, norepinephrine, acetylcholine esterase and dopamine, and those on mathematics was norepinephrine, 5-HT, acetylcholine esterase and dopamine.