The term "Dirty Dozen" in the context of the environment refers to the 12 Persistent Organic Pollutants (POPs). These are a group of highly toxic chemicals that persist in the environment for long periods, accumulate in living organisms, and pose significant risks to human health and the environment.

Persistent Organic Pollutants (POPs) are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. They can be transported over long distances and accumulate in the fatty tissues of living organisms, including humans, causing a range of adverse effects.

The 12 POPs that make up the "Dirty Dozen" were identified and listed under the Stockholm Convention on Persistent Organic Pollutants, a global treaty established in 2001. The aim of the convention is to protect human health and the environment from the effects of these harmful chemicals.

The 12 POPs listed under the Dirty Dozen include:

1. Aldrin: A pesticide used to control pests in agriculture.
2. Chlordane: A pesticide used for termite control and as a wood preservative.
3. DDT: A widely used insecticide for malaria control and agricultural purposes.
4. Dieldrin: A pesticide primarily used to control soil insects and termites.
5. Endrin: A pesticide used for agricultural and industrial purposes.
6. Heptachlor: A pesticide used for termite control and as a soil insecticide.
7. Hexachlorobenzene (HCB): A fungicide used in agriculture and as a chemical intermediate.
8. Mirex: A pesticide used to control fire ants and as a flame retardant.
9. Toxaphene: A pesticide used for agricultural purposes.
10. PCBs (Polychlorinated Biphenyls): Industrial chemicals used in electrical equipment, lubricants, and hydraulic fluids.
11. Dioxins: Chemical compounds produced as byproducts of certain industrial processes and combustion activities.
12. Furans: Chemical compounds produced as byproducts of certain industrial processes and combustion activities.

These substances are highly toxic and can cause a range of adverse effects, including cancer, reproductive disorders, immune system dysfunction, and developmental abnormalities. The Stockholm Convention aims to eliminate or restrict the production, use, and release of these chemicals to minimize their impact on human health and the environment.

In conclusion, the term "Dirty Dozen" refers to the 12 Persistent Organic Pollutants (POPs), highly toxic chemicals that persist in the environment and pose significant risks to human health and the environment. The Stockholm Convention on Persistent Organic Pollutants aims to control and eliminate the production and use of these harmful substances.