An Oakland, CA based organization, Center for Environmental Health, has been conducting independent tests for lead in a variety of products, including reusable bags.
Recently, they released a press release reporting two Disney bags available at Safeway stores with lead levels in violation of California consumer product law and exceeding federal limits. Under the Consumer Product Safety Improvement Act of 2008, children's products currently can not contain more than 300 ppm lead. The Disney "Toy Story" and "Cars" bags were tested at more than 15 times this limit.
CEH has sent legal notices to the bag manufacters in question and requested removal of the bags from stores.
Recent claims have been made by the Center for Consumer Freedom that many reusable bags have unsafe lead and bacteria levels. Read CAW Executive Director Mark Murray's response to those attempts by the plastics industry to scare consumers into using single-use plastic bags here.
Moreover, "CEH's testing confirms that the vast majority of reusable bags do not pose lead hazards, but those few that do are made of plastic." They further recommend cloth reusable bags over plastic reusable bags for their machine-washability and durability.
CEH also tests plastic reusable bags for lead, at no charge. Contact information is available here.
Read the CEH press release here.