Technically, 3rd party testing isn't mandated until August. It's just illegal to sell anything that isn't compliant. So, from your existing stock, how do you even know? Well, you have to test... The good news is, what they term "due diligence" allows XRF testing which is fast and relative inexpensive (unlike certified labs testing that's required in starting in August). One of the large clothing companies I've been testing for lead tests every different STYLE only once, but tests every fabric/button/snap, etc on it. Hope this answer helps somewhat.
Vince Merrill PhD
LeadFreeOC.com