http://www.uscis.gov/graphics/publicaffairs/factsheets/public_cfs.pdf
http://www.uscis.gov/graphics/publicaffairs/questsans/public_cqa.pdf
http://www.uscis.gov/graphics/publicaffairs/summaries/Public.pdf
please read above documents INS (now USCIS) published in 1999.it clearly states that using WIC, Medical assistance like medicaid, chip and other public asssitance will not affect immigrants and their family to ger green card ot to become citizens.