1,2,3-Trimethylbenzene

CASRN 526-73-8

RfD (mg/kg-day)	System	Basis	PoD	Composite UF	Confidence
1 x10^-2	Nervous	Decreased pain sensitivity in male Wistar rats	BMDL_1SD (HED): 3.5 mg/kg-day	300	Low

RfC (mg/m³)	System	Basis	POD	Composite UF	Confidence
6 x 10^-2	Nervous	Decreased pain sensitivity in male Wistar rats	BMDL_1SD(HEC): 18.15 mg/m³	300	Low/Medium

Weight of Evidence for Cancer (PDF) (10 pp, 323 K) last updated: 09/09/2016

WOE Characterization	Framework for WOE Characterization
Inadequate information to assess carcinogenic potential	Guidelines for Carcinogen Risk Assessment (US EPA, 2005)

Basis:

Under the Guidelines for Carcinogen Risk Assessment (U.S. EPA 2005), there is “inadequate information to assess carcinogenic potential” of TMBs. This characterization is based on the fact that there is no information regarding the carcinogenicity of TMBs in humans and that the only animal study available on the carcinogenicity of 1,2,4‑TMB observed no statistically significant carcinogenic effects. No studies regarding the carcinogenicity of 1,2,3‑TMB or 1,3,5‑TMB were identified in the available scientific literature.
This may be a synopsis of the full weight-of-evidence narrative.

Not assessed under the IRIS Program.

Not assessed under the IRIS Program.

Organ/System-Specific RfCs:

System	Basis	RfC (mg/m³)	POD	UF	Confidence
Nervous	Decreased pain sensitivity	5 x 10^-2	BMDL_1SD(HEC): 16.31 mg/m³	300	Low/Medium
Hematologic	Decreased segmented neutrophils	6 x 10^-2	BMDL_1SD(HEC): 16.65 mg/m³	300	Low/Medium
Respiratory	Inflammatory lung lesions	2 x 10^-1	NOAEL: 66.56 mg/m³	300	Low/Medium

1,2,3-Trimethylbenzene is being reassessed.

Assessment Manager(s): Allen Davis (davis.allen@epa.gov)

Step	Assessment Materials Released to the Public	Release Date	Public Meeting Date
1	Problem Formulation Materials	N/A	N/A
1	Preliminary Assessment Materials	N/A	N/A
4	Public Comment Draft	02/2013	N/A
4	Peer Review Draft	08/2013	06/2014
7	Post Final Assessment	09/2016