TRIMETHYLBENZENE, MIXED ISOMERS†

Chemical Identification
Chemical Identification
CAS # 25551-13-7
Formula

C₉H₁₂

Synonyms

[isomers: 1,2,3-trimethylbenzene; 1,2,4-trimethylbenzene; 1,3,5-trimethylbenzene]; hemimellitene; pseudocumene; mesitylene; methylxylene

Physical Properties
Physical Properties
Physical description Clear, colorless liquid with a distinctive, aromatic odor.
Boiling point 329-349°F Molecular weight 120.2
Freezing point/melting point -77 - (-)14°F Vapor pressure varies
Flash point 112-122°F Vapor density
Specific gravity 0.86-0.89 Ionization potential 8.27-8.48 eV
Lower explosive limit (LEL) Upper explosive limit (UEL)
NFPA health rating NFPA fire rating
NFPA reactivity rating NFPA special instruction
Vapor hazard ratio (VHR)
Historical exceedance percentage
Target organs
Monitoring Methods Used by OSHA
Monitoring Methods Used by OSHA
Analyte code (IMIS no.) 2505 2505
Sampling group OVSG-1
Sampler/Sampling media CSC tube (100/50 mg) [SKC 226-01] SKC 575-002 Passive Sampler [SKC 575-002]
Sampling time*

240 min

240 min

Sampling volume (TWA)*

12 L

Sampling flow rate (TWA)*

0.05 L/min

Sampling volume (STEL/Peak/C)*
Sampling flow rate (STEL/Peak/C)*
Analytical method instruments GC-FID GC-FID
Method reference OSHA 5000 (fully validated) OSHA 1020 (fully validated)
Notes

To obtain sampling and analytical error similar to that available with active sampling, knowledge of the atmospheric pressure and temperature are required, and these should be obtained using NIST-traceable devices. If that is not possible, temperature is assumed to be 22.2 °C, and the atmospheric pressure is estimated based on the elevation of the sampling location. When estimates are used in place of traceable measurements the sampling and analytical error associated with passive sampling is substantially increased, and this makes it more difficult to demonstrate overexposures after considering the 95% lower confidence limit.

Special requirements

* All sampling instructions above are recommended guidelines for OSHA Compliance Safety and Health Officers (CSHOs), please see the corresponding OSHA method reference for complete details.

Wipe Method
Wipe Method
Sampler/Sampling media
Bulk Method
Bulk Method
On-Site Screening Techniques
On-Site Screening Techniques
Device
Model/Type
Sampling information
(see manufacturer instructions)
Exposure Limits
Exposure Limits
OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
NIOSH REL
Up to 10-hour TWA
(ST) STEL
(C) Ceiling
ACGIH TLV©
8-hour TWA
(ST) STEL
(C) Ceiling
CAL/OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
PEL-TWA

25 ppm (120 mg/m³) Construction and Maritime Industries ONLY

REL-TWA

25 ppm (125 mg/m³)

TLV-TWA

10 ppm [2021]

PEL-TWA

25 ppm (125 mg/m³)

PEL-STEL REL-STEL TLV-STEL PEL-STEL
PEL-C REL-C TLV-C PEL-C
Skin notation

N

Skin notation

N

Skin notation

N

Skin notation

NA

Notes:

See 29 CFR 1926.55 Table 1 and 29 CFR 1915.1000 Table Z-Shipyards.

Notes: Notes: Notes:
Health factors:  See NIH-NLM PubChem. IDLH
Carcinogenic classifications: TLV-A4 for 1,2,4-trimethylbenzene Notes:
AIHA emergency response planning guidelines - ERPG-1/ERPG-2/ERPG-3:
Additional Resources and Literature References
Additional Resources and Literature References

NOAA: CAMEO Chemicals - 1,3,5-Trimethylbenzene

NIOSH: Pocket Guide to Chemical Hazards - 1,2,3-Trimethylbenzene

Literature References

  • NOAA: CAMEO Chemicals - 1,2,4-Trimethylbenzene.
  • 1,2,4-Trimethylbenzene, 1,3,5-Trimethylbenzene.
  • ACGIH: Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Trimethyl benzene (mixed isomers). See annual publication for most recent information.
  • Järnberg, J., Ståhlbom, B., Johanson, G. and Löf, A.: Urinary excretion of dimethylhippuric acids in humans after exposure to trimethylbenzenes. Int. Arch. Occup. Environ. Health 69(6): 491-497, 1997.
  • Jones, K., Meldrum, M., Baird, E., Cottrell, S., Kaur, P., Plant, N., Dyne, D., Cocker, J.: Biological monitoring for trimethylbenzene exposure - a human volunteer study and a practical example in the workplace. The Annals of Occupational Hygiene. 50 (6): 593-598, 2006.
  • NIOSH: Recommendations for Occupational Safety and Health - Compendium of Policy Documents and Statements. January 1992.
  • NIOSH/CEC/IPCS: International Chemical Safety Cards - Trimethyl Benzene (Mixed Isomers). June 3, 2002.

Last Updated Date : 05/12/2022