Fetal methylmercury poisoning: Clinical and toxicological data on 29 cases

Abstract

This report describes psychomotor retardation in infants caused by prenatal exposure to methylmercury. A study of 29 mother-infant pairs established a relationship between maximum maternal hair mercury concentration during pregnancy and the frequency of neurological effects in the infants. The latter included delayed achievement of developmental milestones with or without neurological signs. The infants were 4 1/2 to 5 years of age on last examination. Ten infants of mothers who had maximum hair concentrations in the range of 99 to 384 pars per million (ppm) had a significantly higher frequency of abnormal findings than those in two groups having lower maternal hair mercury concentrations (12 to 85 and 0 to 11 ppm). The group sizes were too small to allow identification of a specific "threshold" maternal hair concentration above which such effects can be expected. Transient paresthesias during pregnancy occurred in 80% of the mothers in the higher concentration group (99 to 384 ppm) as compared with 30% and 22% in the lower groups. Neurological abnormalities were found in some children whose mothers had been asymptomatic during pregnancy.

Occupational and Environmental Toxicology of Mercury and Its Compounds.

“…A group of mother and infant pairs were examined for the delay in developmental milestones such as walking and talking and the mothers' exposure to mercury, with the hair mercury content of each mother analyzed to determine the peak mercury concentration during pregnancy. Statistical analysis established a doseresponse relationship between the peak mercury concentration during pregnancy and whether first walking or talking was observed or not at the age of 18 or 24 months [48][49][50] . Based on this dose-response relationship, WHO 51) claimed that "A prudent interpretation of the Iraqi data implies that a 5% risk may be associated with the peak mercury level of 10-20 µ/g in maternal hair.…”

Integrated Defense System Overlaps as a Disease Model: With Examples for Multiple Chemical Sensitivity

“…MeHg exposure during pregnancy causes neurologic abnormalities, including psychomotor deficits, mental retardation, and deafness in children (279). Fetal effects occur at much lower exposure levels than required for effects in adults, although in both cases effects are almost exclusively on the nervous system, especially the CNS (268).…”

Neurobehavioral effects of developmental methylmercury exposure.

“…In Iraq, an investigation of 29 mother-infant pairs was initiated after a serious outbreak of MeHg poisoning from consumption of contaminated bread (43). Results indicated a significant relationship between prenatal MeHg exposure and infant psychomotor retardation.…”