Frequent Questions

Reporting by mixture or components for a mixture with unknown chemicals

A facility is storing a product mixture on-site. Under OSHA regulations, the facility is required to retain a material safety data sheet (MSDS) for the mixture.  According to the MSDS, the mixture contains a zinc compound, but no specific chemical identity or concentration information is provided. OSHA regulations allow chemical manufacturers to withhold this information from the MSDS under a trade secrecy claim (29 CFR section 1910.1200(i)).  From the MSDS the owner/operator can not tell whether the proprietary compound is a hazardous chemical (such as zinc silicofluoride) or an extremely hazardous substances (EHS) (such as zinc phosphide).

To comply with Sections 311 and 312 reporting requirements, this facility must determine whether this mixture exceeds the appropriate inventory threshold levels.  How would the facility make this determination?  Once a quantity is calculated, should it be compared to the hazardous chemical threshold of 10,000 pounds, or should the facility owner or operator assume the compound is an extremely hazardous substance (EHS) and use the applicable lower threshold?

Pursuant to 40 CFR section 370.14, a facility may report on a mixture as a whole or on each hazardous component of the mixture. The option of reporting by components, however, is not available if components are not known.  In this case, since the MSDS contains no information on the concentration of the proprietary zinc compound, the facility must report the mixture as a whole.

The next step in evaluating whether a facility is required to report under Sections 311 and 312, is to compare the quantities stored on-site to the appropriate threshold level codified in 40 CFR section 370.10.  For hazardous chemicals that are not EHSs, reporting is required if the facility has over 10,000 pounds on-site at any one time.  For extremely hazardous substances, reporting is necessary if the facility has the chemical on-site in quantities over 500 pounds or the threshold planning quantity (whichever is lower).

In this scenario, the specific identity of the chemical is not available to the facility owner or operator.  Because the facility receives an MSDS for the mixture, the owner or operator knows that the mixture is a hazardous chemical.  While the owner or operator has a duty to make all reasonable efforts to determine whether or not the substance is an EHS, if there is no information reasonably available to this facility owner or operator to make this determination.  Therefore, the regulations do not require reporting the mixture as an EHS.

For the zinc compound mixture, the facility could assume the mixture is a hazardous chemical and apply the 10,000 pounds threshold level to the overall weight of the mixture.  In addition, the facility should state that it is "unknown" whether the mixture is an EHS by writing this in the appropriate box on the applicable form.


Have more questions? Submit a request