We keep MSDS's for 30 years AFTER we stop using the product(s) because of some form of employee exposure record must be kept for 30 years. We choose to just store the MSDS's, including those that are removed due to updates. See the 29 CFR sections below.
OSHA states at 29 CFR 1910.1200(g)(8) that the employer must ensure that the applicable MSDSs are readily accessible to employees during each work shift when the employees are in their work area(s). Thus an MSDS for a chemical must be retained for as long as that chemical is in use.
Under 29 CFR 1910.1020 (c)(5)(iii), the MSDS is considered a form of an employee exposure record. 29 CFR 1910.1020(d)(1)(ii) indicates that employee exposure records must be preserved and maintained for at least 30 years. Therefore, MSDSs must be maintained for this period of time, unless an alternate form of this information is maintained. According to 29 CFR 1910.1020(d)(1)(ii)(B) MSDSs "need not be retained for any specified period as long as some record of the identity (chemical name if known) of the substance or agent, where it was used, and when it was used is retained for at least 30 years." Although this alternate form of keeping exposure records is an option, many organizations choose to maintain MSDSs for at 30 years so that they can preserve not only the required exposure information, but all of the information on the MSDS.