The developmental toxicity of the wide-spectrum
herbicide bromoxynil (
bromoxynil phenol; 3,5-dibromo-4-hydroxyphenyl
cyanide) was evaluated in Sprague-Dawley rats and Swiss-Webster mice, and the developmental toxicity of its
octanoate ester (2,6-dibromo-4-cyanophenyl octanoate) was evaluated in Sprague-Dawley rats. Animals were treated from Day 6 to Day 15 of gestation [presence of sperm or semen plug = 0 of gestation]. The doses administered were as follows:
bromoxynil phenol in the mouse, 342, 114, and 38 mumol/kg/day;
bromoxynil phenol and
bromoxynil octanoate in the rat, 54, 18, and 6 mumol/kg/day. Some animals were killed on selected days during treatment for measurement of organ weights sensitive to stress. In mice treated with
bromoxynil phenol, maternal mortality was noted at 114 and 342 mumol/kg/day, but surviving females gained weight normally. Liver to
body weight ratios increased with increasing dose, but no consistent effect was seen on adrenal, thymus, or spleen weights. Fetuses of mice treated with the highest dose of
bromoxynil phenol were of lower weight and had a higher incidence of supernumerary ribs than controls. In rats,
bromoxynil phenol and its
octanoate ester at the highest doses used caused no mortality but resulted in only transient decreases in
maternal weight gain and significantly increased the liver to
body weight ratio, but did not significantly alter adrenal, thymus, or spleen weight in the dams. No significant maternal effects were seen at lower doses. The highest doses of both compounds increased the incidence of supernumerary ribs in fetuses of treated rats, but did not induce other anomalies.(ABSTRACT TRUNCATED AT 250 WORDS)