Structurally, the halogenated bipyrrole discovered by the Carleton team resembled polychlorinated biphenyls (PCBs), a class of synthetic molecules used as coolants, stabilizers, insulators, and flame retardants whose production was banned in the U.S. in the late 1970s because of concerns over their toxicity and persistence in the environment. But there was no record of this particular compound having ever been synthetically produced. Tittlemier, now a scientist at the Canadian Grain Commission, said she suspected the compound might be a natural product (Environ. Sci. Technol. 1999, DOI: 10.1021/es980646f).
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