Background OSHA predicted the original chemical Hazard Communication Standard (HCS) would cumulatively reduce the lost workday acute injury/illness rate for exposure events by 20% over 20 years and reduce exposure to chemical carcinogens. Methods JoinPoint trend software identified changes in the rate of change of BLS rates for days away from work for acute injuries/illnesses during 1992–2009 for manufacturing and nonmanufacturing industries for both chemical, noxious or allergenic injury exposure events and All other exposure events. The annual percent change in the rates was used to adjust observed numbers of cases to estimate their association with the standard. A case‐control study of EPA's Toxic Release Inventory 1988–2009 data co...