After eliminating confounding factors, the study was made on the relationship between height,
collagen metabolism, hair
zinc and excessive
fluoride intake. 140 schoolchildren aged 12-13 years born and reared in endemic fluorosis areas were surveyed. The results were as follows: 1. The average height of children with
dental fluorosis III degree (DF III degree) was appreciably smaller than that of children without
dental fluorosis. Among children with excessive
fluoride intake, a negative correlation between the height and
fluoride level in staple foods was seen. 2. The more the
fluoride ingested, the higher the urinary THP excreted, showing that
fluoride intoxication interfered with the
collagen metabolism. 3. Among children with excessive
fluoride intake, the height showed negative correlation with urinary THP/Cr, suggesting that the effect of
fluoride on
collagen metabolism indicated the mechanism of height retardation. 4. As compared to control group with the excessive
fluoride intake but without
dental fluorosis group, there was a significant reduction in hair
zinc in group with DF III degree, suggesting that the
zinc in the body decreased because of
zinc metabolism disturbance by excessive
fluoride intake. But among cases with excessive
fluoride intake, no appreciable correlation between hair
zinc and height was found. Therefore, it could not be confirmed that the effect of
fluoride on
zinc metabolism affected the height development.