Chronic organophosphate exposure associated with transient hypertonia in an infant.

OBJECTIVE

A 12-week-old infant girl developed persistent hypertonicity of the extremities, and, at the age of 8 months, it was discovered that her home had been treated with an excessive application of the organophosphate insecticide diazinon 5 weeks prior to the onset of symptoms. An estimation of her daily diazinon dose and possible correlation with her disease was made.

METHODS

Analyses were performed for residues of diazinon in the home and for metabolites of diazinon in the infant. The infant was removed from the home.

RESULTS

Six months after application the remaining diazinon residue on the floor was 230 ng/cm2 vs 38 ng/cm2 expected immediately after a normal application. Vacuum cleaner dust contained 1700 parts per million of diazinon. The air contained 2.8 ng/m3. The infant's urine contained 60 parts per billion of diethylphosphate and 20 parts per billion of diethylthiophosphate which calculates to a diazinon dose of approximately 0.02 mg/kg/d. When the infant was removed from the home, muscle tone returned to normal shortly thereafter.

CONCLUSIONS

The evidence for an association between organophosphate exposure and the sole de-velopment of hypertonicity without other signs of intoxication in an infant is presented. Physicians should consider organophosphate insecticide exposure as a possible cause of hypertonicity in infants.