Hypochlorite Solutions
Pipeline and Hazardous Materials Safety Administration · Oct 7, 1999 · Reference No. 99-0177
Reggie’s quick take
Someone asked whether a 1991 interpretation is still correct that sodium hypochlorite solutions with 7% available chlorine are not corrosive and not subject to the Hazardous Materials Regulations. The agency says that earlier letter was based only on the specific products tested, so it may not apply to other products. Corrosiveness depends on concentration and other ingredients, so each formulation must be checked against the Class 8 criteria in § 173.136 and § 173.137. That job belongs to the shipper under § 173.22, not the agency.
Written by AI (Claude) on Oct 22, 2026. Robots make mistakes and leave things out, so the letter below is what counts. Not legal advice.
This is in response to your letter dated July 2, 1999, regarding whether a 1991 letter of interpretation, written to The Clorox Company, is correct that sodium hypochlorite solutions containing 7% available chlorine is not corrosive, and not subject to the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180).
The letter issued to Mr. Fred Schaefer of the Clorox Company in 1991 was based specifically on data presented by Mr. Schaefer for specified products. This letter may not be valid for other products because the composition (formulation) of hypochlorite solutions may vary from one product to another. The corrosive properties for products containing hypochlorite depend on the concentration of hypochlorite as well as the presence of other ingredients. Therefore, an evaluation of each formulation against the definition and criteria for Class 8 (corrosive) material defined in 49 CFR 173.136 and 173.137 is necessary. This task is the responsibility of the offeror (shipper) as required in 49 CFR 173.22. This Office does not perform that function.
In a final rule published in the Federal Register on December 21, 1990, the HMR was aligned with international standards based on the U.N. Recommendations. The U.N. criteria for corrosive material were adopted, and the ORM-B (Other Regulated Material, category B) hazard class was eliminated. The definition of corrosive material has not changed under the HMR. However, since 1991 "Packing Groups" (i.e., I, II and III), which is a grouping according to the degree of danger presented by the hazardous material, were adopted to determine appropriate packaging for corrosive materials in transportation in commerce. [HM-181; 55 FR 52402, as amended in 56 FR 66124; 12/20/91].
A letter of interpretation applies the regulations to the facts the requester described. It isn’t a regulation and isn’t legal advice. The agency’s copy.