According to one article I found, "Although lead was phased out of printer's ink beginning in 1978, the U.S. Consumer Product Safety Commission doesn't know when its presence actually disappeared. As a result, the agency has ruled that any book printed prior to 1985 might contain the toxic metal."
http://www.helium.com/items/1390555-childrens-books-with-lead-ink
As the article in
La Nación mentions, the presence of lead in printed matter from the U.S. has been a non-issue since about the time Raúl Alfonsin was elected president of Argentina (1983, that is). This is about restricting 'la salida de divisas del país,' as
Nación asserts. But it's an awfully penny-ante way to go about it, rather like a loss-making company restricting the supply of paper clips and urging office workers to make copies on both sides of the paper.
Presumably USA Box customers can still have books sent by postal airmail. At worst, if the lead detector klaxons go off at Aduana, one would only have to go downtown, rather than having to hike out to Ezeiza.
Probably the larger message from these picayune, desperate measures is that one of these days, the peso exchange rate is going to slip out of control. To paraphrase the old chestnut about Gardel, every time I go to 'the cave' to exchange dollars,
'Cada día valora mejor.'