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Chapter 3.2. California Occupational Safety and Health Regulations (CAL/OSHA)
Subchapter 1. Regulations of the Director of Industrial Relations

Article 5. Hazardous Substances Information and Training

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§337. Development and Maintenance of List.

(a) Establishment of Initial List. Substances designated in the sources specified in Labor Code section 6382(b) shall be considered in formulating the initial list.

The Director shall presume all such substances to be potentially hazardous to human health when present occupationally except those which the Director determines do not pose any adverse acute or chronic risk to human health as present occupationally. Those substances which do not pose any risk shall be removed from the list. Evidence of risk shall include any immediate or long-term adverse effect which causes impairment of function, alteration of structure, or increased susceptibility to disease or contributes to adverse effects of other substances. In making a determination of risk, the Director shall consider available scientific data including, but not limited to, data from human epidemiological studies, data from short-term in vitro studies, and data from animal bioassay tests.

Animal bioassay data is admissible and generally indicative of potential effects in humans.

For purposes of this regulation, substances are present occupationally when there is a possibility of exposure either as a result of normal work operations or a reasonably foreseeable emergency resulting from workplace operations. A reasonably foreseeable emergency is one which a reasonable person should anticipate based on usual work conditions, a substance's particular chemical properties (e.g., potential for explosion, fire, reactivity), and the potential for human health hazards. A reasonably foreseeable emergency includes, but is not limited to, spills, fires, explosions, equipment failure, rupture of containers, or failure of control equipment which may or do result in a release of a hazardous substance into the workplace.

(b) Administrative Procedure Followed by the Director for the Development of the Initial List. The Director shall hold a public hearing concerning the initial list. The record will remain open 30 days after the public hearing for additional written comment. Requests to exempt a substance in a particular physical state, volume, or concentration from the provisions of Labor Code sections 6390 to 6399.2 may be made at this time. If no comments in opposition to such a request are made at the public hearing or received during the comment period, or if the Director can find no valid reason why the request should not be considered, it will be incorporated during the Director's preparation of the list.

After the public comment period the Director shall formulate the initial list and send it to the Standards Board for approval. After receipt of the list or a modified list from the Standards Board, the Director will adopt the list and file it with the Office of Administrative Law.

(c) Concentration Requirement. In determining whether the concentration requirement of a substance should be changed pursuant to Labor Code section 6383, the Director shall consider valid and substantial evidence. Valid and substantial evidence shall consist of clinical evidence or toxicological studies including, but not limited to, animal bioassay tests, short-term in vitro tests, and human epidemiological studies. Upon adoption, a regulation indicating the concentration requirement for a substance shall consist of a footnote on the list.

(d) Procedures for Modifying the List. The Director will consider petitions from any member of the public to modify the list or the concentration requirements, pursuant to the procedures specified in Government Code section 11347.1. With petitions to modify the list, the Director shall make any necessary deletions or additions in accordance with the procedures herein set forth for establishing the list. The Director will review the existing list at least every two years and shall make any necessary additions or deletions in accordance with the procedures herein set forth for establishing the list.

(e) Criteria for Modifying the List. Petitions to add or remove a substance on the list, modify the concentration level of a substance, or reference when a particular substance is present in a physical state which does not pose any human health risk must be accompanied with relevant and sufficient scientific data which may include, but is not limited to, short-term tests, animal studies, human epidemiological studies, and clinical data. If the applicant does not include the complete content of a referenced study or other document, there must be sufficient information to permit the Director to identify and obtain the referenced material. The petitioner bears the burden of justifying any proposed modification of the list.

The Director shall consider all evidence submitted, including negative and positive evidence. All evidence must be based on properly designed studies for toxicological endpoints indicating adverse health effects in humans, e.g., carcinogenicity, mutagenicity, neurotoxicity, organ damage/effects.

For purposes of this regulation, animal data is admissible and generally indicative of potential effects in humans.

The absence of a particular category of studies shall not be used to prove the absence of risk.

Negative results generally indicate the absence of statistically positive results in appropriate studies. As all tests for toxicological effects have inherent insensitivities, negative results must be reevaluated in light of the limits of sensitivity of each study, its test design, and the protocol followed.

In evaluating different results among proper tests, as a general rule, positive results shall be given more weight than negative results for purposes of including a substance on the list or modifying the list in reference to concentration, physical state or volume, so that appropriate information may be provided regarding those positive results. In each case, the relative sensitivity of each test shall be a factor in resolving such conflicts.

NOTE: Authority cited: Section 6380, Labor Code. Reference: Sections 6361, 6380, 6380.5, 6382 and 6383, Labor Code.


1. New article 5 (section 337) filed 11-5-81; effective thirtieth day thereafter (Register 81, No. 45).

2. Amendment of subsection (d) filed 1-15-87; effective upon filing pursuant to Government Code section 11346.2(d) (Register 87, No. 3).

3. Editorial correction of HISTORY 2. (Register 91, No. 19).

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