Answer: International stats for children in sweatshops

I've looked through a variety of ILO databases, UN's ODS, Readex's AccessUN, the Index to International Statistics and Statistical Lexis Nexis without finding any estimates. The idea that this activity might be considered illegal in many countries - hence an underground economy - may be a factor in the lack of data. A variety of sources decried the lack or "paucity" of data on the issue. China's build-up of garment producing infrastructure and the change in global garment trade rules provide an interesting context to your question.

oznog adds: I haven't looked at this doc, but it's from the ILO called "A future without child labour." If it doesn't give stats, it should at least give some pointers to stats. There's also a researcher named Kevin Bales that writes and advocates against slavery and especially child labor. his website is "Free the slaves." He's written a book called "Disposable people : new slavery in the global economy."

There's also a document on the International Labour Organization's website called, "A future without child labour." Also on the ILO site is the Statistical information and Monitoring Program on Child Labour (SIMPOC). You'll find statistics there.