Abstract
Phosvel is an organophosphorus pesticide that produces a delayed neurotoxic effect in hens. Residues of Phosvel have been reported to be present in adipose tissue of birds up to 21∼28 days following a single oral dose of 250mg/kg. We here describe accumulation of the pesticide in the fatty tissue of hens given a single, daily administrations of small doses.
Hens (22 months old) were given a single oral dose of 5, 10 or 20mg/kg b.w. of Phosvel daily, and were killed 24 hours after test periods of 7, 14, 21 or 28 days. Three birds that developed signs of paralysis died 3 days before the final dose (28 days).
The concentraion of Phosvel in the fat of hens given 5mg/kg and 10mg/kg increased during the first 21 days, but fell slightly by the termination of the experiment at day 28. Phosvel storage in the fat of birds given 20mg/kg was relatively stable up to 14 days of administration, but increased sharply thereafter. At day 25, the Phosvel concentration in the fat reached a maximum. The level of Phosvel in the fat was proportional to the amount of the daily dose. Three birds given 10mg/kg showed signs of ataxia after the 19th∼26th dose and paralysis after the 20th∼28th dose. Six hens given 20mg/kg showed signs of ataxia after the 17th∼20th dose and paralysis after the 21st∼26th dose.
The results clearly show that Phosvel accumulated in the adipose tissue of hens after continuous exposure and that delayed neurotoxicity in hens was produced following the daily oral administration of 10∼20mg/kg.
