Light Catalytically Cracked Naphtha: Subchronic Toxicity of Vapors in Rats and Mice and Developmental Toxicity Screen in Rats

Abstract

Both a subchronic inhalation study and a developmental toxicity screen were performed with vapors of light catalytically cracked naphtha (LCCN). In the subchronic study, four groups of mice and rats (10 animals per sex per species) were exposed for approximately 13 wk (6 h/d, 5 d/wk) to concentrations of LCCN vapors of 0, 530, 2060, or 7690 mg/m3. An untreated control group was also included. Animals were observed daily and body weights were taken weekly. No significant treatment-related changes were found in clinical signs, body weight, serum chemistry, hematology, histopathology of 24 tissues, or weights of 12 organs. A marginal decrease was noted in the number of sperm per gram of epididymis. In the developmental toxicity screen, presumed-pregnant Sprague-Dawley rats were exposed to 0, 2150, or 7660 mg/m3 of LCCN vapors, 6 h/d on d 0-19 of gestation. Females were sacrificed on d 20; dams and fetuses were examined grossly and fetuses were later evaluated for skeletal and visceral effects. The number of resorptions was increased by approximately 140% in the group receiving 7660 mg/m3; no other definite treatment-related changes were observed. Overall, the effects of exposure to partially vaporized LCCN were minimal.

Toxicological Assessment of Heavy Straight Run Naphtha in a Repeated Dose/Reproductive Toxicity Screening Test

“…2,5,7,8 Several of these articles also reported hematological effects. 2,5,7,8 None of the naphthas 3,4,6,7 or blended gasoline 12,13 has been reported to affect reproductive or developmental parameters when tested at exposure levels that approximated half of the lower explosive limits. Taken together, the effects of the various naphtha streams seem reasonably similar to each other and to blended gasoline.…”

“…Light catalytically cracked naphthas may contain as much as 60% olefins. [4][5][6] 3. Light catalytically reformed naphtha (CAS number 64741-63-5) is a stream manufactured by a process that removes hydrogen, converting cycloparaffins into aromatics.…”

Toxicity Evaluation of Petroleum Blending Streams: Inhalation Subchronic Toxicity/Neurotoxicity Study of a Light Catalytic Cracked Naphtha Distillate in Rats

“…However, Spencer (1984), in a preliminary neuropathology evaluation of a limited number of rats exposed at the highest dose for 18 months, found early indications of axonal dystrophy and degeneration of the spinal cord. Dalbey et al (1996) conducted an inhalation toxicity study on the lighter fractions of LCCN in order to approximate the composition of vapors found in human exposures. In this study, animals were exposed to a maximum target concentration of 2230 ppm (8000 mg/m 3 ) LCCN under conditions of limited vaporization, no more than 50% of the neat LCCN being vaporized.…”