In our July 23, 1998 letter we informed the Agency of some preliminary results of an ongoing multigeneration reproduction toxicity study with the above referenced material. This letter provides addition information from this study. At 300 and 600 ppm, statistically significant reductions in body weight, weight gain and food consumption were observed in F1 male rats. Statistically significant reductions in body weight, weight gain, and food consumption were noted during premating for the 300 and 600 ppm F1 female rats and during gestation in 600 ppm F1 female rats. In addition, reductions in body weight and weight gain (days 0-7) were observed in the 600 ppm Fi female rats during lactation and reduction in body weight in the 300 ppm F1 females during lactation. At 600 ppm, statistically significant reductions in the number of sperm per epididymis, sperm per gram of epididymis, spermatids per testis, and spermatids per gram of testis were observed. The mean implantation efficiency for F1 females was significantly reduced. The mean number of pups born, pups born alive, and pups alive on day 4 preculling were significantly reduced at 600 ppm in the F2 litters. In addition, at 600 ppm, there was a statistically significant reduction in mean pup weight (throughout the entire lactation period) in the F2 litters. At 300 ppm, a statistically significant reduction in the number of sperm per epididymis was observed. Although not statistically significant, there was a biologically relevant decrease in the number of spermatids per testis, as well as spermatids per gram of testis. There were significant reductions in mean pup weight on lactation days 14 and 21 at 300 ppm. Statistically significant reductions were observed in ovarian weights, epididymal weights and cauda epididymal weights in F1 parental rats at 600 ppm. Test substance-related findings were present in the testes and epididymides (F1 males), and livers and thyroid glands of male and female F1 rats. Testicular degeneration/atrophy of seminiferous tubules and corresponding epididymal oligospermia/germ cell debris were present in F1 males at the 600 ppm dose level. In addition, testicular degeneration/atrophy of seminiferous tubules was present in F1 males at 300 ppm. Hepatic cholangiofibrosis and centrilobular fatty change were present in F1 males at 600 ppm. Hepatic cholangiofibrosis (600 ppm), diffuse hepatocellular alteration, midzonal fatty change, and basophilic, cosinophilic, or mixed foci of cellular alteration were present in F1 female rats fed 300 and 600 ppm. An increased incidence of basophilic stained colloid within thyroid gland follicles was present in F1 males and females at the 150, 300 and 600 ppm dose levels.