19085-1701857-UL_Prop_65_Test_Results_2019

CA Prop 65 Cumene NSRL February 11, 2019 Page 3 | 12
1 INTRODUCTION
This report describes the derivation of an NSRL for cumene (CAS# 98-82-8). Cumene was
listed on April 6, 2010 as a chemical known to the State of California to cause cancer under
Proposition 65 (California Health and Safety Code 25249.5 et seq). Cumene is a high
production volume chemical, primarily used as an intermediate in the production of phenol and
acetone. It is also used in the manufacture of styrene, 󰂕-methylstyrene, acetophenone,
detergents and di-isopropylbenzene; as a catalyst for acrylic and polyester-type resins; as a
thinner for paints, enamels and lacquers; as a solvent for fat and resins, and in printing and
rubber manufacture. Minor amounts are used in gasoline blending and as a component of high-
octane aviation fuel. Exposure to cumene may occur via the workplace, the environment,
cigarette smoking and food. The major source of exposure for the general public is through
inhalation of contaminated air. Little exposure occurs from consumer use of products that
contain cumene (IARC 2013). This document discusses the studies used for cancer dose-
response assessment, and summarizes the derivation of the NSRL. A description of the
methodology used is provided in the Appendix A.
2 STUDIES SUITABLE FOR DOSE-RESPONSE ASSESSMENT
Epidemiology Studies
No epidemiology studies examining potential carcinogenic effects of cumene in humans were
found in the literature.
Studies in mice
NTP 2009
Groups of 50 male and 50 female B6C3F
1
mice were exposed by whole-body inhalation to 0,
125 (females only), 250, 500 or 1,000 (males only) ppm cumene (> 99% pure) for 6 hours plus
T90 (the time taken to reach 90% of the target concentration within the exposure chamber; 12
minutes) per day on 5 days per week for 105 weeks. Dose-related increases in the incidence of
alveolar/bronchiolar adenoma and carcinoma were observed in both males and females.
Treatment-related increases in the incidence of haemangiosarcoma of the spleen in male mice
and of hepatocellular adenoma of the liver in female mice also occurred (IARC 2013, NTP
2009).
Table 1. Tumor Incidence in B6C3F
1
Mice (NTP 2009)
Species/Sex Tumor Type
Exposure Level (ppm)
Trend test
1
0
250
500
1,000
Male Mouse
B6C3F
1
Lung
(alveolar/bronchiolar
adenoma)
13/50 31/50** 31/50** 29/50** p < 0.001