Toxicity evaluation of petroleum blending streams: Reproductive and developmental effects of light catalytic cracked naphtha distillate in rats

A distillate of light catalytic cracked naphtha (CAS number 64741-55-5, LCC N-D), administered by inhalation, was tested for reproductive and developme ntal toxicity in Sprague-Dawley rats, following a modified OECD Guideline 4 21, Reproductive/Developmental Toxicity Screening Protocol. LCCN-D was admi nistered as a vapor, 6 h/d, 7 d/wk at target concentrations of 0, 750, 2500 or 7500 ppm to female rats for approximately 7 wk from 2 wk prior to matin g, during mating through gestational d 19, and to males beginning 2 wk prio r to mating for 8 consecutive weeks. Dams and litters were sacrificed on po stnatal d 4, and males were sacrificed within the following week. Parental systemic effects observed at the 7500 ppm exposure level were increased kid ney weights and relative liver weights in males and increased spleen weight s in high-dose females. Livers and spleens from rats in the high-dose group were normal in appearance at necropsy. Increased kidney weights in high-do se males were indicative of male-rat-specific light hydrocarbon nephropathy . No test-related microscopic changes were observed in the reproductive org ans or nasal turbinate tissues of either sex. Reproductive performance was unaffected by treatment with LCCN-D. Fertility index was greater than or eq ual to 90% in ail dose groups. There were no exposure-related differences i n implantation sites and live pups per litter, and no gross abnormalities w ere observed. Pups born from treated dams showed comparable body weights an d weight gains to controls. The viability index on postpartum d 4 was great er than or equal to 97%; the high-dose group had more male than female pups at birth and at d 4 postpartum. Under the conditions of this study, the no -observable-adverse-effect level (NOAEL) for exposure to light catalytic cr acked naphtha distillate for parental toxicity was 2500 ppm and the NOAEL f or reproductive performance and developmental toxicity was 7500 ppm.