SU0007436 SSCRPT - Laserfiche WebLink

Home Browse Search

EXTOXNET PIP- ORYZALIN Page 2 o exhibited decreased uterine and ovarian weights. Those exposed to doses of 75 mg/kg/day showed no observable effects [107]. • Reproductive effects: There were no adverse effects on reproduction in a three-generation study of rats fed dieta concentrations of 12.5, 37.5, or 112.5 mg/kg/day, the highest dose tested. Fetotoxic effects appeared at 12.5 mg/kg/day [58,107]. It does not appear that oryzalin causes reproductive effects. • Teratogenic effects: There were no birth defects in the offspring of pregnant rats fed dietary concentrations as hi as 112 mg/kg/day for three generations, nor in the offspring of pregnant rabbits given doses of 125 mg/kg/day, thl highest dose tested [8,107]. It appears that oryzalin is unlikely to cause teratogenic effects. • Mutagenic effects: Oryzalin was not mutagenic in several tests, including tests on live rats and mice and on bacterial cell cultures [107]. It does not appear that oryzalin is mutagenic. • Carcinogenic effects: When oryzalin was fed to rats in doses as high as 135 mg/kg/day for 2 years, there was an increase in the incidence of thyroid, mammary, and skin tumors [107]. Thyroid tumors and benign skin and mammary tumors occurred in rats fed a dietary level of 45 mg/kg/day for 2 years [107]. However, there were no tumors in mice fed doses as high as 548 mg/kg/day for 2 years [107]. Because of these conflicting results, it is not possible to assess the carcinogenicity of oryzalin. • Organ toxicity: Oryzalin has shown systemic effects on the thyroid, liver, and kidneys, as well as blood chemistr in animal tests. • Fate in humans and animals: Oryzalin is moderately well-absorbed from the gastrointestinal tract, and rapidly metabolized and eliminated following absorption. When oryzalin was administered to male rats,40% of the dose was excreted in the urine and 40% in the feces within 3 days. Similar results were obtained in tests with rabbits, a steer, and with Rhesus monkeys [106]. Ecological Effects: • Effects on birds: Oryzalin is slightly toxic to practically non-toxic to birds; the reported oral LD50 values in bobwhite quail and mallard ducks are greater than 500 mg/kg, and in chickens is 1000 mg/kg [1,58]. The 5-day dietary LC50 values in quail and mallard ducks are greater than 5000 ppm [8]. • Effects on aquatic organisms: Oryzalin is highly toxic to fish,with reported 96-hour LC50 values of 2.88 mg/L bluegill sunfish, 3.26 mg/L in rainbow trout, and greater than 1.4 mg/L in goldfish fingerlings [8]. • Effects on other organisms: The reported oral LD50 for the compound in bees is 11 ug/bee, indicating it is nontoxic to bees [1,58]. Environmental Fate: • Breakdown in soil and groundwater: Oryzalin is of low to moderate persistence in the field, with reported field half-lives ranging from 20 to 128 days [58,11]. A representative value for soil half-life is estimated to be 20 days [11,58]. Microbial degradation is mainly responsible for the breakdown of oryzalin in soils, but it may undergo photodecomposition near the soil surface [58]. Volatilization is not appreciable [58]. Oryzalin is slightly soluble ii water and it does not have a strong tendency to adsorb to soil particles [58,11]. It is bound to a greater extent with increasing soil organic matter and clay content. In soils with low proportions of these, high water tables and increased rainfall, oryzlin may be mobile, and thus present a risk of contamination to groundwater. • Breakdown in water: No breakdown of oryzalin by hydrolysis was observed at pH 5, 7, and 9 [8]. Based on its behavior in soil, breakdown by microbial processes is probably slow in the aquatic environment due to low levels oxygen and low microbial activity. Photodegradation may be significant in the upper portions of the water column • Breakdown in vegetation: Oryzalin is readily absorbed via the roots, and plant metabolism of oryzalin is minima [58]. Physical Properties: ittp://extoxnet.orst.edu/pips/oryzalin.htm 7/2/20