Moving on to the kitchen, Greene suggests that all parents, but especially those bottle-feeding, "get to know their plastics a little bit." Bottles made with polycarbonate have been getting attention lately for possibly leaching BPA, a chemical that is a known hormone disruptor. BornFree is one brand he recommends in the book as BPA-free. Those tiny recycling numbers stamped on most plastics can be a good short-hand guide to safety. Number 3, which indicates Polyvinyl chloride (PVC), sometimes used on bottle nipples, "is dangerous." Number 7 is the miscellaneous category. "Unless something on the package indicates that it's good, it could be very bad," he cautions. Categories 1, 2, 4 and 5, are the safest. Turning to what a baby breathes, some of his simplest and cheapest advice is to open a window or take your tyke for a walk. "Most fumes that are a problem come from inside." But the one item he urges parents to splurge on: an organic cotton mattress. Conventional mattresses are filled from the inside out with toxic chemicals from phthalates to fire retardants that emit toxins you don't want your little one breathing. Babies spend a lot of hours sleeping, he points out. This eco-friendly measure will absolutely be a splurge. At BabiesRus, an organic mattress from Serta was $180 on sale, versus $80 for a conventional mattress from the same brand. It seems that every day a new hazard emerges that parents need to avoid to raise a healthy baby and be nice to the Earth. Having an easy to use guide to help you do it -- and do it affordably -- is a big help. This was previously published on TheStreet.com on March 18, 2008 at 10:55 a.m. EDT.