My understanding is the same as weesandy.
US buyers are bound by US law. *if* there were going to be a problem with a US buyer buying from you, it would be on their end as they are the US citizen bound by US law.
BUT
these items are not illegal nor have they been deemed dangerous and open for seizure at the border.
Items with LEAD have been deemed dangerous and illegal.
And in order for that to be ascertained an item must be tested and certified etc.
And in order for that to happen, the law reads that the IMPORTER must do this... therefore items must reach the importer, therefore your buyer gets their goods.
IF that is the end of the line, that is, they bought for personal use. End of story, no problem.
IF they are buying for resale, that is, to sell on the US commercial market the items must become certified and that is THEIR responsibility as the importer. Of course, as an importer they may not buy from you in Canada is certifyingis going to be an issue/ expense for them, which is where it would affect your business.
So, yes, you can sell to the US. You must comply with Canadian law. You are not breaking any US laws. It is as if JOhnny USA came over to Canada and bought a tedy bear and drove back home. IF there is issue with the teddy, it is his issue, not yours (ie the border guards aren't going to march teddy bear back to you and slap YOUR wrist).
Same as me wanting to buy a plastic bottle with PBA. Illegal to sell in Canada, but I can order online from the US and have it show up at my door without issue.
Long answer, I know, but US law applies to US citizens, products and markets. The CPSIA law is geared to items entering the US market as saleable goods. Selling from Canada to a US citizen for personal use is at the buyer's own risk.
L