Workers' comp
Cumulative trauma (CT)
A work injury caused by repetitive physical or mental activity over time, rather than one incident, with its own date-of-injury and liability rules.
What cumulative trauma is
California recognizes two kinds of injury: specific, from one incident, and cumulative, from repetitive mentally or physically traumatic activities over a period of time whose combined effect causes disability or a need for treatment (Labor Code section 3208.1). Repetitive-motion injuries, back and neck conditions from years of lifting, and some psychiatric claims are typically pleaded as CTs.
The rule
The date of a cumulative injury is the date the employee first suffered disability from it and knew, or reasonably should have known, that it was caused by work (Labor Code section 5412). That date drives the one-year statute of limitations to file (Labor Code section 5405). Liability is limited to the employers who employed the worker during the one year immediately before that date of injury or the last date of injurious exposure, whichever comes first (Labor Code section 5500.5).
Why it matters to an applicant firm
A CT often runs alongside a specific injury, each with its own ADJ number. Pleading the right period matters: it determines which employers and carriers are on the hook and whether the claim is timely. Defense carriers often argue for an earlier date of injury to raise a limitations defense, or seek apportionment between the specific injury and the CT. The intake interview should capture job duties, dates of employment, and when the client first missed work or got treatment. See the cumulative trauma guide.
Sources
General information about California and federal rules, not legal advice. Rules change and every case turns on its facts: check the statute and your own analysis before relying on a date or a figure.