Decision on the New and Revised B.C. Exposure Limits based on the 2019 and 2020 ACGIH TLVs for Selected Chemical Substances

At its May 2024 meeting, WorkSafeBC’s Board of Directors (BOD) approved the adoption of the 2019 and 2020 new and revised American Conference of Governmental Industrial Hygienists Threshold Limit Values (ACGIH TLVs) for the following selected chemical substances:

• Chromium and Inorganic Compounds: Metallic Chromium, as Cr(0)
• Cobalt and inorganic compounds, as Co
• Cyclopentadiene
• Dicyclopentadiene
• Dicyclopentadiene, including Cyclopentadiene (8-hour TWA only)
• Manganese, elemental and inorganic compounds, as Mn
• Resin acids, as total resin acids
• Rosin core solder thermal decomposition products (colophony)
• 1,1,2,2-Tetrabromoethane
• Tin and inorganic compounds, excluding tin hydride and indium tin oxide, as Sn
• Tin and inorganic compounds, excluding Tin hydride, as Sn, Metal
• Tin and inorganic compounds, excluding Tin hydride, as Sn, Oxide and Inorganic compounds

Effective July 10, 2024, these substances will be removed from the Table of Exposure Limits for Excluded Substances in Policy R5.48-1 of the Prevention Manual and the ACGIH TLVs will be assigned as B.C. exposure limits:

Substance	B.C. exposure limits
	8-hour time-weighted average limit	Short-term exposure limit	Ceiling limit
Chromium and inorganic compounds: Metallic chromium, as Cr(0)	0.5 mg/m3 (Inhalable)	—	—
Cobalt and inorganic compounds, as Co	0.02 mg/m3 (Inhalable)	—	—
Manganese, elemental and inorganic compounds, as Mn	0.1 mg/m3 (Inhalable) 0.02 mg/m3 (Respirable) (unchanged)	—	—
Resin acids, as total Resin acids	0.001 mg/m3 (Inhalable)	—	—
Rosin core solder thermal decomposition products (colophony)	— (Withdrawn)	—	—
1,1,2,2-Tetrabromoethane	0.1 ppm	—	—
Tin and inorganic compounds, excluding Tin hydride and Indium tin oxide, as Sn	2 mg/m3 (Inhalable)	—	—
Tin and inorganic compounds, excluding Tin hydride, as Sn, Metal	— (Withdrawn)	—	—
Tin and inorganic compounds, excluding Tin hydride, as Sn, Oxide and Inorganic compounds	— (Withdrawn)	—	—

Due to sampling issues, the BOD decided not to adopt the new or revised ACGIH TLVs for the following substances:

• Dicyclopentadiene, including Cyclopentadiene (15-minute short-term exposure limit only)
• Formamide
• Indium tin oxide, as In
• Isobutyl nitrite
• Methyltetrahydrophthalic anhydride isomers
• Methyl vinyl ketone
• Monomethylformamide
• o-Phthalaldehyde
• Propylene glycol ethyl ether
• Styrene oxide
• Sulfur pentafluoride
• m-Xylene α,α'-diamine

A decision on the adoption of new or revised ACGIH TLVs for styrene will be postponed after WorkSafeBC undertakes further analysis and review of the recently published health studies.

For these substances, the existing exposure limits will be maintained in the Table of Exposure Limits for Excluded Substances in Policy R5.48‑1 of the Prevention Manual.

For Dicyclopentadiene, including Cyclopentadiene, the BOD adopted the ACGIH TLV of 0.5 ppm (8-hour exposure limit), but did not adopt the ACGIH TLV of 1 ppm (15-minute short-term exposure limit) as a B.C. exposure limit due to sampling issues. The adopted B.C. exposure limit for Dicyclopentadiene, including Cyclopentadiene, will supplant the existing B.C. exposure limits for Cyclopentadiene and Dicyclopentadiene (as noted above).

Effective July 10, 2024, Dicyclopentadiene, including Cyclopentadiene, will be reflected in the Table of Exposure Limits for Excluded Substances in Policy R5.48-1 of the Prevention Manual as B.C. exposure limits as follows:

Substance	B.C. exposure limits
	8-hour time-weighted average limit	Short-term exposure limit	Ceiling limit
Dicyclopentadiene, including Cyclopentadiene	0.5 ppm	—	—
Cyclopentadiene	— (Withdrawn)	—	—
Dicyclopentadiene	— (Withdrawn)	—	—

WorkSafeBC will continue to monitor the availability of sampling methods for all of these substances, as well as to work on ongoing initiatives to develop, validate, and implement sampling methods.

Sincerely,

Lori Guiton
Director, Policy, Regulation and Research Department
WorkSafeBC