Blair, et.al.,

Given the stunningly awesome array of humor, cynicism, inaccurate advice and tangents I wanted to actually address Blair's original question ;).

The fact is that manufacturers - and sellers - of products that can expose users to any of literally hundreds of chemicals (most of which are not used in products and are in place because other activities can expose people) have been responsible for marking their products since the late 1980s. The only thing that changed in August is the wording of the warning. Why this suddenly caught the industry's attention I can't say.

It has less to do with what the product "contains" than with what the product can "expose" a user to. That is, expose dermally, through inhalation or ingestion..."lead in the copper used to make the board" is not - normally - going to be exposed to a user - that's not a reason to declare. Determining whether you have to provide a warning requires some thought and diligence. It also applies to occupational uses, not just consumer uses.

Useful links:
Regulatory language: https://oehha.ca.gov/proposition-65/law/proposition-65-law-and-regulations
Business Q&A: https://www.p65warnings.ca.gov/sites/default/files/art_6_business_qa.pdf
List of chemicals: https://oehha.ca.gov/proposition-65/chemicals

It's a complex and frustrating regulation because it is very different from every other substance restriction/disclosure requirement in one critical aspect: it's not based on concentration limits but rather on "exposure", which is dependent on material, use and toxicological assessment.

I hope this helps.

Mike