Difference Between Dioxins and PCBs

Thekey differencebetween dioxins and PCBs is that大多数二恶英是天然存在的物质，永远不会出于任何目的而合成，而PCB是用于各种技术目的的物质。

Dioxins and PCBs are toxic chemical compounds that can persist in the environment, accumulating in the食物链. Therefore, these are harmful chemicals. PCBs are a derivative of dioxins, or we say, PCBs are dioxin-like compounds. Both dioxins and PCBs are considered as environmental pollutants.

内容

1.Overview and Key Difference
2.What are Dioxins
3.什么是PCB
4.Side by Side Comparison – Dioxins vs PCBs in Tabular Form
5.概括

What are Dioxins?

Dioxins are a group of chemical compounds that are considered as persistent environmental pollutants. Most members of this group are highly toxic compounds. These compounds are grouped together since their mechanism of action regarding the toxic effect is the same. E.g. these compounds tend to activate aryl hydrocarbon receptor (AH receptor) in different binding affinities depending on the chemical structure of the dioxin compound.

图01：1,4-二恶英的化学结构

二恶英化合物的毒性取决于分子中氯原子的数量及其位置。毒性等效因子（TEF）是关于二恶英化合物毒性的重要概念。该因素的发展是为了促进风险评估和监管控制。

Dioxin compounds are virtually insoluble in water but are soluble in lipids. Thus, this makes these compounds able to associate with organic matter such as浮游生物，植物叶和动物脂肪。除此之外，这些化合物倾向于吸收到无机颗粒中，例如灰分和土壤。这些是非常稳定的化合物，并且倾向于通过食物链积聚。

什么是PCB？

PCB或polychlorinated biphenyl compounds是一组具有通用化学式C12H10-XCLX的有机氯化合物。这些化合物曾经被广泛部署为电式和冷却液的液体，在电气仪，无碳复印纸和传热液中。PCB的摩尔质量根据化学公式中“ X”的值而变化。但是，PCB以浅黄色出现或无色。这些是厚的油性液体。

Figure 02: General Structure of PCBs

PCB化合物被认为是可能导致环境污染的有机污染物。由于其特征寿命，它们仍在使用，但是由于其环境毒性，其生产自1960年以来一直大大减少。它们被归类为持续的有机污染物。根据一些研究，PCB可以引起动物的癌症，并且是人类的可能致癌物。这些化合物可以在食物链中积聚，包括许多河流，建筑物，公园和其他地点。

PCB compounds are structurally similar to dioxin compounds, and their toxic mode of action is also the same. However, PCBs can cause extra toxic effects, such as endocrine disruption and neurotoxicity.

PCB compounds are slightly soluble in water but are soluble in organic solvents. Therefore, we can categorize these compounds as hydrophobic compounds. PCB compounds are soluble in oils, and fats as well. These compounds exist as pale yellow coloured or colourless viscous liquids having a low vapour pressure at room temperature. These substances show a high thermal conductivity and a high flashpoint.

Similar to most other organic environmental pollutants, PCBs do not break down or undergo degradation easily, making them attractive for industries. These compounds are resistant to acids, bases, oxidation, hydrolysis, and temperature changes as well. Moreover, these compounds can generate extremely toxic compounds such as dibenzodioxins and dibenzofurans through partial oxidation.

More importantly, PCB compounds can easily and readily penetrate our skin, PVC structures, and latex structures; however, there are some PCB resistant materials as well, e.g.Viton, polyethylene, PVA, PTFE, nitrile rubber, Neoprene, etc.

二恶英和PCB有什么区别？

二恶英和PCB化合物是有机污染物。二恶英和PCB之间的关键区别在于，大多数二恶英是天然存在的物质，永远不会出于任何目的合成，而PCB是用于各种技术目的的物质。因此，由于人类活动，二恶英已经存在于环境中，而PCB被释放到环境中。

以下是表格形式的二恶英和PCB之间的差异的摘要。

概括– Dioxins vs PCBs

Dioxins and PCBs are stable compounds containing chlorine atoms attached to hydrocarbon compounds. These are considered as organic pollutants. The key difference between dioxins and PCBs is that most of the dioxins are naturally occurring substances and never synthesized for any purpose, whereas PCBs are substances that were synthesized for various technical purposes.