Notice of Intent to List: Beta-Myrcene

The California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) intends to list the chemical beta-myrcene as known to the State to cause cancer under the Safe Drinking Water and Toxic Enforcement Act of 1986.¹  This action is being proposed under the authoritative bodies listing mechanism.²

Background on listing via the authoritative bodies mechanism:  A chemical must be listed under the Proposition 65 regulations when two conditions are met:

1. An authoritative body formally identifies the chemical as causing cancer (Section 25306(d)³).
2. The evidence considered by the authoritative body meets the sufficiency criteria contained in the regulations (Section 25306(e)).

However, the chemical is not listed if scientifically valid data which were not considered by the authoritative body clearly establish that the sufficiency of evidence criteria were not met (Section 25306(f)).

The National Toxicology Program (NTP) is one of several institutions designated as authoritative for the identification of chemicals as causing cancer (Section 25306(m)).

OEHHA is the lead agency for Proposition 65 implementation.  After an authoritative body has made a determination about a chemical, OEHHA evaluates whether listing under Proposition 65 is required using the criteria contained in the regulations.

OEHHA’s determination:  Beta-Myrcene meets the criteria for listing as known to the State to cause cancer under Proposition 65, based on findings of the NTP (NTP, 2010).

Formal identification and sufficiency of evidence for beta-myrcene:  In 2010, the NTP published a report on beta-myrcene (β‑myrcene), entitled Toxicology and Carcinogenesis Studies of β-Myrcene (CAS No. 123-35-3) in F344/N Rats and B6C3F1 Mice (Gavage Studies), that concludes that the chemical causes cancer (NTP, 2010).  This report satisfies the formal identification and sufficiency of evidence criteria in the Proposition 65 regulations.

OEHHA is relying on the NTP’s discussion of data and conclusions in the report that beta-myrcene causes cancer.  The NTP (2010) states in the Conclusion section of the report’s Summary (page 5):

“We conclude that β-myrcene caused kidney cancers in male rats and liver cancer in male mice…”

The NTP (2010) report states in the Conclusion section of the report’s Abstract and main body of the report (pages 8 and 63):

“Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenic activity of β‑myrcene in male F344/N rats based on increased incidences of renal tubule neoplasms…

“There was clear evidence of carcinogenic activity of β‑myrcene in male B6C3F1 mice based on increased incidences of hepatocellular adenoma, hepatocellular carcinoma, and hepatoblastoma.”

Thus, the NTP (2010) has found that beta-myrcene causes increased incidences of combined malignant and benign kidney tumors in male rats and malignant and combined malignant and benign liver tumors in male mice.

Request for comments⁴:  OEHHA is requesting comments as to whether beta-myrcene meets the criteria set forth in the Proposition 65 regulations for authoritative bodies listings.  In order to be considered, OEHHA must receive comments by 5:00 p.m. on Monday, March 10, 2014 Monday, March 24, 2014.  We encourage you to submit comments via e-mail, rather than in paper form. Comments transmitted by e-mail should be addressed to P65Public.Comments@oehha.ca.gov with “NOIL-beta-myrcene” in the subject line. Comments submitted in paper form may be mailed, faxed, or delivered in person to the addresses below:

Mailing Address:
Office of Environmental Health Hazard Assessment
P.O. Box 4010, MS-19B
Sacramento, California 95812-4010
Fax: (916) 323-2265
Street Address: 1001 I Street
Sacramento, California 95814

Comments received during the public comment period will be posted on the OEHHA web site after the close of the comment period.

If you have any questions, please contact Sam Delson at sam.delson@oehha.ca.gov or at (916) 445‑6900.