Tollund Man was unearthed in a Danish peat bog perfectly preserved even though he died in the century before Christ. He is exactly the same as a contemporary human in every respect save one: his body contains no chemicals. We are host to many chemicals that arrive in our bodies through numerous pathways. We don't like chemicals, they're everywhere, in us all, and seemingly poisonous. Most man-made chemicals have yet to be tested for toxicity. Yet we're living longer, healthier lives than our Iron Age forebears. So does a chemically polluted world matter? Earth Report goes to three continents to investigate this chemical conundrum to find out what we know about the health impacts of chemicals, how they're spreading and if we can really be safe with so many of them?