among the most studied are polybrominated diphenyl ethers, or pbdes. scientists have linked pbdes to a wide range of conditions, from delayed development to learning problems and diminished intelligence. >> the neuro-developmental effects--so that's exposures during pregnancy or early in life, lininking to neuro-d-developmental effects in animimals, have e now been evaluated in two human studies. so there's one in a population in n new york and one in a population in california. anand what they find is actually remarkably similar. these developmental exposures to pbdes arere actually linked to detriments in i.q. >> two pbdes, penta and octa, were taken off the u.s. market voluntarily in 2004 because of growing health concerns. production of the pbde deca is in the process of being terminated. >> the problem with all of these pbddes is that they y are very persistent in the environment. >> the issssue with pbdes is tht they've been replaced with other types of f chemicals that mayaye verery similar concerns and perhaps even the same mechanism of action,