Warning Label Requirements and Safe Harbor Levels for Silica under California Proposition 65

Question Posed:

What are the safe harbor levels for silica?  Is it mandatory to include the warning labels on products?

Answer Provided:

Silica appears to be specific to respiratory issues during manufacturing (from the occurrences/uses section).  If, after the manufacturing of the products, there is a chance of a consumer inhaling the silica above the 3 μg/m³ per day exposure threshold, then a label is likely needed.  If there is no chance of exposure or it is below the 3 μg/m³ per day limit, then a label is probably not required. There is likely still a need to provide the information to workers under OSHA, but the Prop 65 warning requirement would not be applicable to the manufacturing process where end-users are not making purchases of finished goods.

Here is an excerpt from the Proposition 65 website about Silica:

  • Silica (crystalline, respirable)
    • Air
    • Chronic REL
Chronic Inhalation REL (μg/m3):   3
Chronic Target Organs: Respiratory system
  • Occurrence(s)/Use(s)
    • Manufacture of glass, abrasives, ceramics, enamels, heat insulators, fire- and acid-prove packing materials; clarifying and filtration agent, molds for castings, decolorizing and purifying oil/petroleum, industrial filler

Reference: https://oehha.ca.gov/chemicals/silica-crystalline-respirable

**Article contents valid as of 2017-06-13

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