Persistent Organic pollutants (POPs) are used to cover various chemical structures with varying levels of toxicity. They are resistant to environmental degradation and accumulate inside living creatures, including humans.
Persistent organic pollutants have come under persistent and considerable international scrutiny in the past few decades. These chemical compounds collectively possess several chemical and physical properties that permit them to spread over long distances, bio-accumulate, and turn resistant to degradation.
Exposure to these chemical compounds has been associated with various adverse effects both in humans and wildlife.
The Stockholm Convention has a role in facilitating worldwide efforts to identify and classify these classes of compounds. They are at present highlighted through the initial identification of 12 persistent organic pollutants. They are referred to as the Dirty Dozen for convenience. They consist of 8 pesticides, 2 industrial chemicals, and 2 by-products of burning or industrial processes.
Properties Of Persistent Organic Pollutants
Persistent organic pollutants share a combination of bio-accumulation and persistence. Such features are a result of their chemical substances’ physical and chemical characteristics. The range of the impact that POP has on the environment and the need to cut down and eliminate them has in recent years become a cause for concern.
As POPs can easily be transported over very long distances by water and wind, they can affect countries far from where they were initially generated. They thus can affect wildlife and humans far from their place of origin and release.
Persistent organic pollutants also persist for very long periods, at times decades, in the environment. They can also accumulate and pass on from one species to the next, moving through the food chain.
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While a wide range of adverse effects has been identified, the most relevant are the issues of developmental deformity and the lethal danger it poses to the embryo. These effects peaked between the 1960s and 1980s, but it continues to persist.
All persistent organic pollutants are organic, thus are carbon-containing. But they are not natural or related to any living matter. They are all synthetic.
These dangerous chemicals are all released by humans into the environment and include industrial chemicals, pesticides, and discharges from industrial processes. They are created both intentionally or as a byproduct. Industrial products and pesticides are created intentionally. But industrial processes and combustion create persistent organic byproducts.
POPs have been around for decades, but it is only in recent years that humans have recognized their dangerous qualities and have tried to stop their use and propagation.
The knowledge about the dangers of POPs finally forced many countries to ban or limit their production, use and release into the atmosphere. The efforts finally led to the Stockholm Convention on Persistent Organic Pollutants.
One of the major impetus that led to the Convention was the discovery of traces of POP contamination in the pristine Arctic regions, thousands of miles from major industrial activity. It points to evidence of long-range airborne particulate substances and gases.
Some POPs get carried for miles through water evaporation or when they are absorbed by airborne particles. They then settle on land and water bodies in the form of rain, mist, or snow. POPs can also travel through water bodies such as rivers, lakes, oceans, and even through animal carriers such as migratory species.
Over 180 nations are signatories to the Convention. They have agreed to immediately eliminate and finally eliminate the release of POPs into the environment.
Persistent Organic Pollutants And Their Effect On Life
The WHO and the Environmental Protection Agency have put forward 3 attributes of persistent organic pollutants, and they have been acknowledged in various scientific studies.
All scientists agree that POPs are extremely toxic to humans and cause damage years after they are no longer in use in the area. They adversely affect the nerves and the nervous systems, while also affecting the immunity system leading to cancer and cardiovascular diseases.
They lead to endocrine disruption which causes developmental and reproductive disorders. They also get deposited in fatty tissues of animals, fish, and birds, and humans. They get deposited in the placenta, impairing human embryos and cause harm to embryos and fetuses.
They get transported easily through water and wind, spreading over incredible distances. Environmental scientist Xu Baiqing explains that since persistent organic pollutants are unstable, they easily evaporate and are carried by the wind, settling down over cold regions. This explains their accumulation in the remote corners of the planet including over Mount Everest and other mountains of the Himalayan region and the Tibetan plateau.
Origin Of POPS
POPs began to be produced on an industrial scale in the 1940s. It was Rachel Carlson, science journalist and marine biologist who first alerted the authorities to the overall danger of the two chemicals. In her book, Silent Spring, published in 1962, she had awakened humans to the health damage and environmental destruction caused by persistent organic pollutants.
Though Carlson had based her book on exhaustive scientific evidence, the chemical and allied industry, and vested interests fiercely attacked her and even vilified her personally.
Then-President John F Kennedy entrusted the task of investigating Carlson’s claim to the President’s Science Advisory Committee, which found her findings to be valid.
It led to the formation of the US Environmental Protection Agency. The environmental movement in the US was born. DDT, one of the most harmful and widespread Persistent Organic Pollutants was banned.
The UN Environmental Programme compiled a primary list of a dozen persistent organic pollutants that studies found were particularly threatening. A year later, the UN Environmental Programme adopted the list put out by the Stockholm Convention in May 2001, and it went into effect in May 2004.
The Eight Banned POP Pesticides
The Convention has been endorsed by 184 nations. Dieldrin and Aldrin are two of the pesticides. They were developed in the 1950 and were used broadly on crops. In 1972 its use was banned by the EPA though it was used against termites until 1987. Both are extremely toxic compounds and dangerous to all life forms. even today its residue is present in the soil in the US.
Chlordane was another broad-spectrum pesticide that was utilized in agriculture, plus in-home gardens until the late 1970s. Its use continued for another decade against termites. It is proven as carcinogenic and harms birds and fish.
DDT is the most known among the chemicals and has been around since WW II. It was used both for agriculture and against termites. But it caused extensive damage, especially to birds of prey who began laying chicks with fragile shells that failed to hatch the chicks. Birds like the bald eagle populace were pushed to extinction.
DDT’s main use was in the control of malaria-causing mosquitoes. It is the reason that it is still used in some countries.
Endrin is chemically close to dieldrin. It was also used as a regular insecticide and to kill birds and rodents. Its traces persist for around 12 years and are highly dangerous to fish. Heptachlor is another insecticide with properties similar to DDT.
All 12 Persistent organic pollutants targeted under the Stockholm Conventions are also endocrine disruptors, chemicals that interfere with the hormones of the body. Chemicals that disrupt the endocrine are particularly hazardous even in low doses and are dangerous to the fetus. Endocrine disruptors alter development and destabilize the ability to fight disease, reproduce, and learn.
The American kestrel and the Canadian geese population were destroyed after eating seeds contaminated with this chemical. It was around till the first decade of this century to destroy fire ants in cable boxes placed underground. Mirex was another multi-purpose insecticide used for termites, mealybugs, fire ants, and yellow jackets. They were even used as an effective fire retardant. Though banned in 1977, traces are still present in water and soil.
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Toxaphene is a mixture comprising more than 670 chemicals and was a common insecticide till the 1970s. It was used in lakes to eliminate unwanted fish. It is still in use in some countries.
Industrial Chemicals Banned Under The Stockholm Convention
Polychlorinated biphenyls (PCBs) are a set of 209 chemicals in industrial usage as coolants. Moreover, they were utilized in copy papers and certain paints. Manufacturing and usage were banned domestically in 1979 but they continue to be generated inadvertently as derivatives of varied manufacturing processes.
Hexachlorobenzene (HCB) was used as a fungicide for the manufacture of fireworks, synthetic rubber, and ammunition, and on seeds. Its manufacture has been stopped but it is a byproduct of several solvents and pesticides. It has been categorized as carcinogenic.
Some persistent organic pollutants come as unintended byproducts of other chemical processes. Furans and Dioxins are derivatives of combustion, manufacturing of pesticides and chemicals, and the process of chlorine bleaching. Chemically, they are similar to PCBs and are equally toxic.
Eliminating Persistent Organic Pollutants
Another 9 chemicals were added to the dozen in the list of persistent organic pollutants under the Stockholm Convention. Several of them are still widely used as retardants, pesticides, and in varied industrial processes.
Lindane, for instance, is useful for treating lice, though it is a prescribed medicine. Perfluorooctane sulfuric acid is used to make flame retardants, semiconductors, and flat screens. It is even used as an insecticide against termites and ants.
Personal care products and cosmetics are two industries that continue to rely on several of the new persistent organic pollutants on the list of the Stockholm Convention. Organic fluorine was traced in over half of the 231 products marked for personal care in Canada and the US.
Organic fluorine belongs to a category of banned chemicals included in the list. It is toxic and persistent but is still used in many beauty products. Liquid lipsticks, waterproof mascaras, and foundations were found to contain significant traces of this chemical. And significantly, none of the brands tested listed organic fluorine as a chemicals contained in the product. The research paper that published the report did not specify brands, products, or manufacturers.
But this report led to some significant legislation. The report in various news articles by Green Science Policy Institute led to a couple of Senators from either side of the political divide to introduce the ‘No PFAS in Cosmetics Act.’
Senators Richard Blumenthal and Susan Collins were behind this bill and if passed, would oblige the FDA to prohibit the use of PFAS in cosmetics and would even require online sites selling these products to warn customers and give full labeling.
But little headway has been made and it could be a lengthy process. This is evidenced by the resistance faced by Senator Diane Feinstein who has been leading different legislations requiring companies to label their products and register all their facilities. But the bills have made little headway.
California’s Governor Newsom has been the first to sign legislation banning the utilization of toxic chemicals in personal products and cosmetics, including PFAS. But the law will be effective only in 2025.
This year Maryland barred the production of and trade in cosmetics containing toxic components.
In an alarming revelation, the Environmental Working Group, a non-profit advocacy group comprising lawyers, policy experts, scientists, and data and communications experts wrote on their website that the US was far behind the EU and Japan in banning the use of toxic chemicals in personal care products and cosmetics.
The EWG stated that over 40 countries that included leading industrialized economies such as Germany and the UK, and even developing economies such as Vietnam and Cambodia already have in place regulation that specifically targets the ingredients and safety of personal products and cosmetics.
Several of these countries have enacted laws to ban or restrict over 1,400 toxic chemicals from being used in personal products or cosmetics. But the US FDA has restricted or banned 7 chemicals so far.
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The list of the persistent organic pollutants changes and more chemicals get added to it. However, there remains approximately 30,000 chemicals in the world, and among them are numerous unknown Persistent Organic Pollutants. One of the latest case is the recent discovery of the global diffusion of PFOS. For these reasons, the dirty dozen list will keep growing with time and cannot be deleted from memory.
There has been a concentrated global effort to shift from the use of these toxic chemicals to a sustainable approach to production and consumption in different industrial processes. It includes the application of methods that will ultimately lead to the formation of a circular economy, a successful material-cycle system, and sustainable management of materials.