What are Persistent Organic Pollutants?
"DDT, a widely used insecticide in the world, will take between 5 and 17 years for its quantity to be reduced by half"
Because of their persistence, they diffuse in the environment and contaminate the soil, water and air. Significant quantities can be measured at great distances from the sources of pollution.
POPs are fat-soluble, i.e. they accumulate in adipose tissue (fat) and are not easily eliminated from exposed organisms: they are bioaccumulative.
For these reasons, they contaminate the entire food chain. The accumulation is all the more important as one goes up the food chain. Consequently, Man, located at the top of the food chain, is particularly exposed to them.
Due to their high toxicity, this bioaccumulation has health effects on humans.
The main POPs are insecticides, industrial products or unintentional pollutants released into the environment.
What are the main POPs concerned by the Stockholm Convention?
Insecticide used in particular for wood treatment and in agriculture
Insecticide used in the cultivation of bananas (West Indies), tobacco and cereals
Flame retardant used in clothing, furniture foam, mattresses and building insulation
Insecticide used to replace DDT
Insecticide, rodenticide (rodents) and piscicide (fish)
Fungicide for the treatment of cereals such as wheat
Agricultural insecticide and pharmaceutical treatment for lice and scabies
alpha-HCH and beta-HCH
Impurities produced during the synthesis of lindane
Intermediate in the synthesis of insecticides, flame retardant, additive to PCBs
Insecticide and fungicide.
Polychlorinated biphenyls (PCB)
Electrical insulator in high voltage transformers, hydraulic fluid, mineral oil additive, flame retardant.
Insecticide and acaricide (spiders)
Agricultural insecticide and mosquito treatment.
What are the main health effects of POPs?
The main health effects of POPs are:
- Endocrine disruptors
- Attention disorders in exposed children
- Metabolic syndrome (altered metabolism leading to type 2 diabetes, heart disease and stroke)
- Behavioral disorders
- Neurological disorders (Neurotoxic)
According to the texts of the Stockholm Convention:
"Specific effects of Persistent Organic Pollutants may include cancer, allergies and hypersensitivity, damage to the central and peripheral nervous systems, reproductive disorders and disruption of the immune system. Some Persistent Organic Pollutants are also considered endocrine disruptors which, by altering the hormonal system, can damage the reproductive and immune systems of exposed individuals as well as their offspring; they may also have developmental and carcinogenic effects."
Because of their bioaccumulative properties and resistance to biological degradation processes, impacts are also observed far away from emission sources and long after their use has ceased.
Why does exposure to Persistent Organic Pollutants pose a greater risk to pregnant and lactating women?
POPs easily cross the placental barrier and expose the baby "in utero. Because they bind to fatty tissue, they contaminate breast milk.
For these reasons, pregnant and nursing women should avoid exposure to POPs.
What are the sources of exposure to Persistent Organic Pollutants?
Persistent organic pollutants have become widely distributed in the environment. Human exposure to POPs occurs primarily through inhalation of ambient air and ingestion of water and food. The foods that include the most POPs are fatty meat and fatty fish.
Because of their past use and reduced biodegradability, POPs continue to pollute the soil.
It should also be noted that POPs-treated roofing materials have a lasting effect on the indoor environment of homes, exposing the occupants on a daily basis.
Occupational exposure to Persistent Organic Pollutants
In theory: there is no more occupational exposure, as a consequence of the ratification of the Stockholm Convention, the products in question are now banned in many countries.
In reality: due to their persistence, POPs, which have been widely used in agriculture and industry, can continue to generate occupational exposure even years after their ban.
Professionals specializing in the processing and recycling of transformers may be particularly exposed to PCBs.