Substances not present on the list of hazardous substances adopted pursuant to Section 6380 shall not be subject to the provisions of this chapter. However, the absence of designation as a hazardous substance in the list adopted pursuant to Section 6380 shall not in any way affect any other liability of an employer with regard to safeguarding the health and safety of an employee or other persons exposed to a toxic or hazardous substance; nor shall it affect any other duty or responsibility of a manufacturer, producer, or other maker to warn ultimate users of a substance pursuant to other provisions of law.