What is "octachlorodibenzodioxin"

Octachlorodibenzodioxin (can be abbreviated as OCDD) is one of polychlorinated dibenzodioxins (PCDDs). Its toxicity is similar to TCDD, but it is about 3000 times weaker. It is one of the dominant dioxin congeners in smoke emissions, but because it is much less soluble than e.g. TCDD, it is not bioaccumulated as effectively and it is toxicologically less important than the most prevalent dioxins (for details see Dioxins and dioxin-like compounds).