- Any of several carcinogenic, mutagenic, and teratogenic polychlorinated heterocyclic aromatic hydrocarbons that can occur as impurities in petroleum-derived herbicides and as byproducts of manufacturing chemicals and burning fuels and waste.
- any of a broad range of <xref>toxic</xref> or <xref>carcinogenic</xref> <xref>halogenated</xref> <xref>polycyclic</xref> <xref>compounds</xref> that occur as <xref>byproducts</xref> of <xref>herbicides</xref>
- the <xref>parent compound</xref>, dibenzo-p-dioxin, in which two <xref>benzene</xref> rings are connected vio two <xref>oxygen</xref> atoms; <xref>oxanthrene</xref>
- the <xref>unsaturated</xref> six-membered <xref>heterocycle</xref> having four <xref>carbon</xref> atoms, two <xref>oxygen</xref> atoms and two <xref>double bonds</xref>
- any of several toxic or carcinogenic hydrocarbons that occur as impurities in herbicides