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Chronic organophosphate exposure associated with transient hypertonia in an infant
1Department of Agricultural Chemistry, Oregon State University, Corvallis 97331-7301.
Insights
Infant hypertonicity was linked to excessive organophosphate insecticide (diazinon) exposure in the home. Muscle tone normalized after removal, suggesting a causal relationship in this pediatric case.
Area of Science:
- Environmental Toxicology
- Pediatric Neurology
- Occupational Health
Background:
- Organophosphate insecticides are widely used but can pose risks, especially to vulnerable populations like infants.
- Persistent hypertonicity in infants can have various causes, necessitating thorough investigation of environmental factors.
Observation:
- A 12-week-old infant presented with persistent extremity hypertonicity.
- The infant's home environment showed significantly elevated diazinon residues months after application.
- The infant's urine contained diazinon metabolites, indicating significant exposure.
Findings:
- Calculated daily diazinon dose was approximately 0.02 mg/kg/d.
- Hypertonicity resolved shortly after the infant was removed from the contaminated home environment.
- Elevated diazinon levels in home dust, air, and on surfaces confirmed excessive insecticide application.
Implications:
- This case highlights the potential for organophosphate insecticide exposure to cause isolated hypertonicity in infants.
- Physicians should consider environmental organophosphate exposure in the differential diagnosis of infant hypertonicity.
- Public health awareness regarding safe insecticide application practices is crucial to prevent pediatric exposures.
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.
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