| Organophosphate Insecticides with No Active EPA Registration (as of 2002) |  |
| Dairy calves <2 wk of age sprayed with water-based formulations showed poisoning at 0.05% or higher concentrations, and adult cattle were poisoned by spraying with 1%. Sheep and goats have been poisoned by 22 mg/kg body wt, PO, but not by 8 mg/kg. The LD50 for rats is ~31 mg/kg; a daily dosage of 2.2 mg/kg for 90 days produced poisoning. Dogs tolerated a diet containing 32 ppm for 90 days. |
| Adult cattle were poisoned by 5% or higher sprays, while young calves were poisoned only when the concentration was raised to 2%. The minimum oral toxic dose appears to be ~22 mg/kg for cattle of all ages. The acute oral LD50 for rats is 10-39 mg/kg. |
| Crotoxyphos is of rather low toxicity; however, Brahman cattle are markedly more susceptible than European breeds. Cattle (except as above), sheep, goats, and pigs all tolerate sprays containing crotoxyphos at 0.5% levels or higher. Toxic doses appears to be in the 2% range, except for in Brahman cattle, in which 0.144%-0.3% may be toxic. |
| The oral LD50 is 8 mg/kg body wt in goats and 2 mg/kg in rats; the dermal LD50 in rats is 8 mg/kg. |
| Dioxathion is a mixture of cis- and trans-isomers (70%) and reaction products (30%). Used on both plants and animals, it is rapidly metabolized and not likely to produce residues in meat greater than the 1 ppm official tolerance. Concentrations of 0.15% or greater are generally used on animals. The minimum toxic dose in calves is 5 mg/kg body wt. Sprays of 0.5% in cattle and sheep or 0.25% in goats and pigs are nontoxic. Dioxathion at 8.8 mg/kg, PO, has killed young calves, and
it produced intoxication at 4.4 mg/kg. |
| EPN is related to parathion (see above) and is about one-half as toxic when applied externally; when given PO, it is about equally toxic. Dogs were not poisoned at doses >100 mg/kg. |
| The maximum nontoxic dose is 10 mg/kg body wt in calves and 50 mg/kg in cattle, sheep, and horses. This compound is effective against warbles in cattle, but (as for all grubicides) directions must be followed as to time of application; larvae killed while migrating and the resultant local reaction can cause serious problems. |
| The LD50 in rats is 3 mg/kg body wt, PO or topically. |
| Ronnel produces mild signs of poisoning in cattle at 132 mg/kg body wt, but severe signs do not appear until the dosage is >400 mg/kg. The minimum toxic dose in sheep is 400 mg/kg. Concentrations as high as 2.5% in sprays have failed to produce poisoning of cattle, young dairy calves, or sheep. Poisoning usually occurs in 2 stages. The animal first becomes weak and, although able to move about normally, may be placid. Diarrhea, often flecked with blood, may also be seen.
Salivation and dyspnea then appear if the dose was high enough. Blood cholinesterase activity declines slowly over 5-7 days. Ronnel produces residues in meat and milk; strict adherence to label restrictions is essential. The residues may be removed by giving the animal activated charcoal for several days. |
| Ruelene is active both as a systemic and contact insecticide in livestock, has some anthelmintic activity, and has rather low toxicity. Dairy calves have been poisoned by 44 mg/kg body wt, PO, while adult cattle require 88 mg/kg for the same effect. Sheep are moderately intoxicated by 176 mg/kg; Angora goats are about twice as sensitive. Pigs have been poisoned by 11 mg/kg and horses by 44 mg/kg. Most livestock tolerate a 2% topical spray. |
| This soil insecticide is used to control corn rootworms. The minimum oral toxic dose is ~1.5 mg/kg body wt for sheep and cattle. Cases of intoxication in cattle have occurred. Ingestion of 7.5 mg/kg was lethal to heifers. |
| TEPP is one of the most acutely toxic insecticides. Although not used on animals, accidental exposure occurs occasionally. One herd of 29 cattle (including calves and adults) was accidentally sprayed with 0.33% TEPP emulsion; all died within 40 min. |
