According to the US Mint the penny cost 2.4 cents to produce, more than twice its face value.
http://www.usmint.gov/faqs/circulating_coins/?action=faq_circulating_coin
The US penny is made out of 97.5% zinc and a 2.5% copper coating. Tolerable upper intake levels of zinc for 19+ year old males/females is 40 mg, a penny weighs 2.5 grams. Exposure to higher levels of ingested zinc can cause adverse health complications including "significant increases in hospitalization".
http://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/#disc
Not are only pennies cost ineffective, they are a danger to our children, our pets, and anyone who ingests the zinc based coin. US Mint estimates 140 billion in circulation.
The penny should be recycled into ammunition to help our troops protect and serve.