CHRONIC ORGANOPHOSPHATE EXPOSURE ASSOCIATED WITH TRANSIENT HYPERTONIAIN AN INFANT

Objective. A 12-week-old infant girl developed persistent hypertonicit y of the extremities, and, at the age of 8 months, it was discovered t hat her home had been treated with an excessive application of the org anophosphate insecticide diazinon 5 weeks prior to the onset of sympto ms. An estimation of her daily diazinon dose and possible correlation with her disease was made. Methods. Analyses were performed for residu es of diazinon in the home and for metabolites of diazinon in the infa nt. The infant was removed from the home. Results. Six months after ap plication the remaining diazinon residue on the floor was 230 ng/cm(2) vs 38 ng/cm(2) expected immediately after a normal application. Vacuu m cleaner dust contained 1700 parts per million of diazinon. The air c ontained 2.8 ng/m(3). The infant's urine contained 60 parts per billio n of diethylphosphate and 20 parts per billion of diethylthiophosphate which calculates to a diazinon dose of approximately 0.02 mg/kg/d. Wh en the infant was removed from the home, muscle tone returned to norma l shortly thereafter. Conclusions. The evidence for an association bet ween organophosphate exposure and the sole de-velopment of hypertonici ty without other signs of intoxication in an infant is presented. Phys icians should consider organophosphate insecticide exposure as a possi ble cause of hypertonicity in infants.