Dichlorvos (DDVP) Risk Characterization Document - California ...

APPENDIX C
NALED
TOXICOLOGY OF NALED AND TRICHLORFON
Naled, 1,2-dibromo-2,2-dichloroethyl dimethyl phosphate is an organophosphate with insecticidal
activity. It is used on crops and in structures for insect control. In 1990, 450,000 pounds of naled
applied in California and the distribution was 54% for lemons, 12% for oranges, 10% for fresh or
processed grapes, 7% for safflower, and 3% for cotton (DPR, 1991).
Acute toxicity
Naled was acutely toxic to laboratory animals when administered by the oral, dermal, and inhalation
routes. Cholinergic signs (such as salivation, convulsion, tremors, death) were observed in all the
species tested. Pathological changes were observed in some tissues. Congested lungs and pale
kidneys were observed in rats after oral exposure. The skin of rabbits exposed to naled dermally
showed damage including necrosis, fibrosis, and ulceration. The lowest acute oral NOEL was 10
mg/kg-day for cholinergic signs in rats and rabbits.
Subchronic and chronic toxicity
The current Toxicology Summary (8/25/94) shows that there are no data gaps. All of the following
studies were conducted by gavage administration. No adverse effects were found in the mouse
oncogenicity, rat teratology, rabbit teratology, or neurotoxicity studies. Adverse effects were found in
the dog chronic, rat chronic and oncogenicity, and rat reproductive toxicity studies. In the dog chronic
study, the adverse effects (NOEL = 0.2 mg/kg-day) were the inhibition of brain, plasma, and
erythrocyte ChE activities, degeneration of the testes, focal mineralization of the spinal cord, and mild
siderosis in the spleen. In the rat chronic and oncogenicity study, the NOEL was also 0.2 mg/kg-day
for the inhibition of brain, plasma, and erythrocyte ChE activities. There was a slight increase in the
incidence of mammary adenocarcinoma in male rats (by gavage). In the two-generation reproductive
toxicity study with naled, the only significant parental effect was a dose-related decrease in body
weight in all treated F 1 males during both pre- and post-mating periods. The effects on the pups
included decreased survival, body weight, and number of pups at birth with a NOEL of 2 mg/kg-day.
The only inhalation study reviewed showed corneal and nasal lesions in the rat exposed to naled (A
3.4 ug/L) by inhalation for 3 weeks.
Genotoxicity
No adverse effects were found in the gene mutation (Ames assays), chromosomal aberration (bone
marrow), and DNA damage (unscheduled DNA synthesis) studies.