California Code, Labor Code - LAB § 6397

(a) Any person other than a manufacturer who sells a mixture or any hazardous substance shall provide its direct purchasers of the mixture or hazardous substance at the time of sale with a copy of the most recent MSDS or equivalent information prepared and supplied to the person pursuant to either Section 6390 or subdivision (b) whenever it is foreseeable that the provisions of this chapter may apply to the purchaser.

(b) Any person who produces a mixture may, for the purposes of this section, prepare and use a mixture MSDS, subject to the provisions of Section 6395.

(c) Any person subject to the provisions of subdivision (a) shall be relieved of the obligation to provide a specific purchaser of a hazardous substance with an MSDS if he or she has a record of having provided the specific purchaser with the most recent version of the MSDS, or if the product is one sold at retail and is incidentally sold to an employer or the employer's employees, in the same form, approximate amount, concentration, and manner as it is sold to consumers, and, to the seller's knowledge, employee exposure to the product is not significantly greater than the consumer exposure occurring during the principal consumer use of the product.