Overview

Unintentionally produced Persistent Organic Pollutants (U-Pops) are toxic chemicals that are unintentional by-products such as dioxins and furans which are difficult to decompose, far spread, and accumulate in human adipose tissues as well as animals and thus have a long-term toxic impact on health and environment. These pollutants are one of the major contributors to environmental pollution and have become a huge concern due to their unique characteristics: long-range transport, transformation and bioaccumulation, harmful toxicological impact, semi-volatility, recalcitrant nature, and long half-lives. The channel through which UPOPs spread through the environment is diversified and hence deteriorates our surroundings i.e., soil, water, and air. They can travel long distances and enter several atmospheric processes such as air-water exchange and cycles involving rain, snow, and dry particles. The pollutants can even be found in remote places far away from where they were initially released, and this has been termed as grasshopper effect. For instance, it is said that some toxic pollutants are affecting the life in the Polar Regions which are very far from the industrialized world.

The seven UPOPs listed in Annex C of the Stockholm Convention include:

  • Hexachlorobutadiene (HCBD) - HCBD was used as a solvent for other chlorine - containing compounds. It was listed in Annex C in 2017
  • Polychlorinated naphtalenes (PCN) - PCNs were used as insulating coatings for electrical wires, as wood preservatives, as rubber or plastic additives for capacitor dielectrics and in lubricants. It was listed since 2015
  • Pentachlorobenzene (PeCB) - PeCBz was used in PCBs products in dyestuff carriers as a fungicide, a flame retardant, and as a chemical intermediate, e.g. for the production of quintozene.
  • Polychlorinated biphenyls (PCBs) - have been used as coolants and lubricants in transformers, capacitors, and other electrical equipment because they do not burn easily and are good insulators. It was listed in 2004 
  • Hexachlorobenzene (HCB) - HCB has been used as a pesticide to protect the seeds of onions and sorghum, wheat, and other grains against fungus. It has also been used to make fireworks, ammunition, and synthetic rubber.
  • Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF) - PCDD and PCDF are released during incomplete combustion of municipal waste or medical waste in open burning settings. They were manufactured for laboratory purposes rather than to be used as commercial products.

Article 5 of the Stockholm Convention states that Parties must take measures to reduce, and where feasible, eliminate releases of unintentionally produced POPs.

Sources

U- POPs are formed by products from various processing activities. These pollutants can reach the environment through industrial effluent, agricultural runoff, urban runoff, drainage systems, landfill leachate, and deposition from the atmosphere. The major sources of U-POPs are classified as follows:

  • Metals smelting, refining, and processing: UPOPs can be formed by metals operation which includes ore sintering, scrap metal recovery, and metal smelting.
  • Combustion: UPOPS can be formed through combustion activities such as waste incineration, high-temperature sources, and uncontrolled combustion including open burning, forest fires, etc.
  • Biological and photochemical process: It can also be formed by biodegradation, decomposition, and fermentation at specific conditions.
  • Reservoirs: UPOPs can also be released from existing sources such as soil, sediments, dumpsites, to the atmosphere from previous accumulation.
  • Industrial wastewaters: They can be found in wastewaters from processes that involve chemical usage or production

Effects of U-POPs on Humans and the Environment

Because UPOPs are difficult to decompose and can easily spread far, they easily enter into the food chain through diverse means in the environment. As such, they have a long-term toxic impact on health and the environment. The effects can be classified as Acute and Chronic.

Acute Effect (Short term exposure to high concentrations)

Several skin diseases including acne, patchy darkening of the skin, chloracne, etc.

Headaches, dizziness, nausea, Conjunctivitis inflammation

Chronic Effect (long term exposure to lower concentrations)

The chronic effects can lead to the dysfunction of various systems in the human body:

Nervous system

Endocrine system

Immune system

Carcinogenicity

This causes cancer, hormonal disturbances, gastrointestinal problems, reproductive defects, obesity etc