There was a question about the possible toxicity of the popular foam puzzle mats that children play with and on. The concern is about exposure to formamide being released. This chemical is used in the manufacture of ethylene vinyl acetate (EVA) foamed plastics to make them more pliable. It's a liquid, but like any liquid formamide does evaporate. There is no question that exposure to the liquid should be avoided; it is corrosive and has been linked to problems in a developing embryo. But the small amounts that outgas from foam present a totally different situation. The vapour dissipates quite quickly but nevertheless French and Belgian authorities deemed some levels unacceptable and established limits of formamide release from foams used in childrens' play mats and toys. Studies, however, show that outgasing drops off very quickly and the amounts that could conceivably be inhaled by children playing on EVA foam mats are way below levels that could cause health issues. I certainly wouldn't let my grandson play on an EVA mat, which he does quite often, if I thought there was any risk.