A Carleton University PhD student is mapping out a molecule that blurs the traditional dividing line between bad industrial pollutants and good natural chemicals. Sheryl Tittlemier's newfound chemical behaves like some of the nastiest industrial pollutants in the world and it comes from something natural in the oceans. Man-made pollutants such as PCBs and dioxins mix chlorine with organic chemicals to make something that lasts for decades without breaking down and can damage the reproductive systems of humans and animals. Natural chemicals were always supposed to break apart in the environment, not build up in wildlife over time.