Acute poisoning with phosphamidon: determination of dimethyl phosphate (DMP) as a stable metabolite in a case of organophosphate insecticide intoxication.

Many organophosphate pesticides (OP) such as phosphamidon are unstable in aqueous solutions and especially in blood in the presence of esterases. In a case of intoxication, the phosphamidon concentration in serum decreased from 10 mg/L to 4.4 mg/L after storage at -20 degrees C for six months; nearly complete degradation was observed after three years. Dimethyl phosphate (DMP) is a metabolite of phosphamidon, mevinphos, dicrotophos, monocrotophos, dichlorvos, and trichlorfon. A gas chromatographic-mass spectrometric method with deuterated DMP-d6 as internal standard for the determination of DMP in biological material was validated. DMP was found in all of the patient's samples (3.9 and 4.9 mg/L in blood, 33.5 and 50.4 mg/L in urine, and 8.1 mg/L in gastric fluid), even after storage at -20 degrees C for up to 3 years. No hints for a degradation of DMP when spiked in fresh blood and stored at 4 degrees C for 1 week and stored in water over a time period of 10 months. Looking for the stable metabolites like DMP in cases of suspected OP intoxication is recommended.

Experiences with acute organophosphate poisonings in Crete.

Nine human acute poisonings due to intentional ingestion of organophosphorous pesticides are presented. Six of the victims died. Six patients were treated in the Intensive Care Unit (ICU) from 34 h to 45 d, while 3 were found dead by relatives. Two of the patients treated in the ICU fully recovered after 15 and 24 d while the third survivor developed delayed neuropathy. Organophosphate blood levels were determined on admission and during therapy, and in 1 case atropine and pralidoxime levels were also detected. Significant fluctuations of the plasma cholinesterase activity were observed during therapy. Postmortem analysis revealed higher levels of pesticides in organs (eg 23.1 micrograms fenthion/g kidney) and in fat (135.2 micrograms fenthion/g) than in blood (eg 4.8 micrograms fenthion/ml) and vitreous humor. Considerable pesticide was measured in testis (eg 5.8 micrograms fenthion/g, 0.8 micrograms methidathion/g) and uterus (170.5 micrograms malathion/g). Extracorporeal decontamination to enhance pesticide elimination is a therapeutic challenge.