California Proposes a Lower TCE Exposure Limit: Review Your Solvent Controls

What changed — and what has not

California's Occupational Safety and Health Standards Board has opened consultation on a substantial reduction in the workplace exposure limit for trichloroethylene, commonly called TCE. The rulemaking notice was published on 30 October 2026.

The proposal would amend section 5155, Table AC-1, lowering the eight-hour time-weighted average permissible exposure limit from 25 ppm to 0.24 ppm (1.3 mg/m³). It would also withdraw the existing 100 ppm short-term exposure limit and 300 ppm ceiling. Those are proposed changes, not permission to relax existing controls.

The consultation closes on 17 December 2026, with written comments due by 5 p.m. and a public hearing scheduled that day. The official status page does not list an adoption or effective date. Do not describe 0.24 ppm as California's current enforceable limit or as a worldwide standard.

Why this matters beyond a regulatory number

TCE is used in applications including metal degreasing. The Board's notice explains that the proposed reduction addresses cancer risk not adequately covered by the older limit. A lower benchmark can expose weaknesses in an assessment that previously appeared satisfactory.

NIOSH identifies inhalation, skin absorption, ingestion and eye or skin contact as exposure routes. An air sample alone does not answer every exposure question. For HSSE teams worldwide, the practical lesson is to revisit the evidence behind solvent controls while separately confirming the requirements that apply in their own jurisdiction.

Start with an inventory of tasks, not just products

The following is our practical control-review framework, not a quotation from the proposed rule. Check safety data sheets and purchasing records for TCE and CAS number 79-01-6. Walk the process with operators, cleaners and maintenance staff. Include decanting, loading, unloading, drying, filter changes, tank cleaning, waste transfer and non-routine breakdown work.

Record who may be exposed, how often and under what operating conditions. Include contractors and nearby workers. An inventory that stops at the main production line can miss the task that drives the greatest exposure.

Build a defensible measurement plan

Ask a competent occupational hygienist to design representative personal monitoring. Agree the analytical method and reporting limit with the laboratory before sampling; a result reported only as “not detected” is not useful if its reporting limit is too high for the question being asked.

Connect results to actual tasks, shift duration, ventilation condition and production rate. Consider short-duration tasks as well as whole-shift exposure. Do not treat a single area reading, a quiet production day or absence of solvent smell as proof of control. Existing California section 5155 requires monitoring where excessive exposure is reasonably suspected and competent industrial-hygiene supervision of monitoring and control methods.

Use substitution and engineering controls together

• Reduce the need to clean: review upstream oils, contamination and production steps.
• Evaluate alternatives: test whether a lower-hazard chemical or aqueous process meets the required finish and cleanliness. EPA's historical case studies illustrate that alternatives can work; they are not approval of a particular substitute for your process.
• Manage the change: assess toxicity, flammability, compatibility, ventilation, waste and wastewater consequences before approval. A replacement can introduce a different hazard.
• Contain and capture: assess enclosed equipment, closed transfer and effective local exhaust. Verify performance during the tasks that actually release vapour, including maintenance.
• Protect against contact: choose gloves and eye protection using chemical-specific compatibility information and the task assessment. Do not assume a generic disposable glove is suitable.
• Plan abnormal work: define isolation, spill response and stop-work conditions. Respirator selection requires a competent, chemical-specific assessment and a properly managed programme; do not assume a basic organic-vapour cartridge is adequate.

Leadership and toolbox questions

• Where is TCE still used, including in maintenance products and contractor work?
• Which exposure assessment is supported by recent personal samples under representative conditions?
• Who verifies extraction performance, and what happens when it fails?
• What evidence will show that a substitution reduces overall risk?
• Who owns the regulatory review and any consultation response?

Video availability

No directly relevant, authoritative, embeddable video was verified for this update. Use the linked official proposal and technical references rather than an unrelated safety video.

Key takeaway

A proposed lower limit is an opportunity to test your exposure-control evidence. Confirm the legal status, find every relevant task, measure appropriately and improve the process. Keep current legal duties and any voluntary planning benchmark clearly separated.

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