I was under the impression that pops was some kind of horrid Yorkshire dish involving hot milk and bits of bread but this is not the case. Rather POPs are a small set of toxic chemicals that remain intact in the environment for long periods and accumulate in the fatty tissues of animals.

POPs stands for persistent organic pollutants, also classed as PBTs (Persistent, Bioaccumulative and Toxic) or TOMPs (Toxic Organic Micro Pollutants.)

• Persistant because they are are resistant to natural biodegradation. They do not break down and can last for decades.
• Pollutants because they are highly toxic, causing death, disease, and birth defects among humans and animals.

How can you avoid them? You cant! They travel through the environment through the atmosphere (windbourne), the food web (by being eaten) and through the waterways by attaching themselves to particles in water. POPs released in one part of the world can be transported many hundreds of miles away from the original source. POPs have been discovered in remote regions where they have never been used, the middle of oceans and Antarctica.

Pops can enter the food chain at the most basic of levels. “Planktonic organisms are the first link for pollutant transfer in the pelagic system. Traditionally, primary producers, (all those organisms that are able to synthesise organic matter capturing the energy of the sunlight) such asphytoplankton have been considered as the initial step for transport of POPs into food webs. Recent studies, however, point out that the capacity of uptake of bacteria is an important route for POPs transportation via the microbial food chain. The microbial food chain is the link between microorganisms in the sea.” From GPA website.

Because POPs are not soluble in water but readily absorbed and retained in fatty tissue of animals, this leads to a process called Biomagnification, also known as bioamplification or biological magnification. This is, is the increase in concentration of a substance that occurs in a food chain as a consequence of:

Food chain in a swedish lake. From the bottom: freshwater shrimp, bleak, perch, northern pike, osprey (Photo credit: Wikipedia)

• Persistence (can’t be broken down by environmental processes)
• Food chain energetics
• Low (or nonexistent) rate of internal degradation/excretion of the substance (often due to water-insolubility)

Which means as POPs pass up the food chain, they increase exponentially. For example lets say that each bit of plankton contains 1 POP. A worm eats 5 plankton so now it contain 5 POB, 5 worms are in turn is eaten by a fish (25) and 3 fish are caught by a fisherman (75). The higher up the food chain the more you absorb.

It is claimed that plastic particles in the sea attract POPs.

Related articles

• Enhanced desorption of persistent organic pollutants from microplastics under simulated physiological conditions (microplastic.wordpress.com)

Where Do Pops Come From

Most are created by humans in industrial processes, either intentionally or as byproducts.

Many POPs are currently or were in the past used as pesticides. Others are the result of industrial processes. Including plastic manufacture and disposal

In May 1995, the United Nations Environment Programme Governing Council (GC) began investigating POPs. and 2001 the Stockholm Convention on Persistent Organic Pollutants was formed to organise the severe restriction of their production, by the international community.

State parties to the Stockholm Convention on Persistent Organic Pollutants. Italiano: Stati ratificanti della Convenzione di Stoccolma sugli inquinanti organici persistenti. (Photo credit: Wikipedia)

These are related to the plastic industries

Dioxins

They are of concern because of their highly toxic potential.

Once dioxins have entered the body, they endure a long time because of their chemical stability and their ability to be absorbed by fat tissue, where they are then stored in the body.

Their half-life in the body is estimated to be seven to eleven years.

In the environment, dioxins tend to accumulate in the food chain. The higher in the animal food chain one goes, the higher the concentration of dioxins.

Doixin is a known human carcinogen and the most potent synthetic carcinogen ever tested in laboratory animals. Find out lots more here.

Dioxins occur as by-products in the incineration of chlorine-containing substances such as PVC (polyvinyl chloride), in the chlorine bleaching of paper, and from natural sources such as volcanoes and forest fires, waste incineration, and backyard trash burning, and herbicide manufacturing. More on burning plastic here.

Polychlorinated Biphenyls (PCBs) compounds are used as additives in paint, carbonless copy paper, and plastics.

Of the 209 different types of PCBs, 13 exhibit a dioxin-like toxicity. Their persistence in the environment corresponds to the degree of chlorination, and half-lives can vary from 10 days to one-and-a-half years.

PCBs are toxic to fish, killing them at higher doses and causing spawning failures at lower doses. Research also links PCBs to reproductive failure and suppression of the immune system in various wild animals, such as seals and mink.

Read more about PCBs here.

And here are some more…

Aldrin is an organochlorine insecticide that was widely used until the 1970s, when it was banned in most countries.

Chlordane a pesticide,  It was sold in the United States from 1948 to 1988, both as a dust and an emulsified solution. It is now banned.

DDT, First synthesized in 1874, DDT’s insecticidal action was discovered by the Swiss chemist Paul Hermann Müller in 1939.  A worldwide ban was formalised under the Stockholm Convention, but its limited use in disease vector control continues to this day and remains controversial.

Dieldrin  an alternative to DDT, and a highly effective insecticide widely used during the 1950s to early 1970s. Long-

term exposure has proven toxic to a very wide range of animals including humans.It is now banned in most of the world.

Endrin  A pesticide. Currently, the use of endrin is banned in many countries.

Heptachlor was used as an insecticide. Animals exposed to Heptachlor epoxide during gestation and infancy are found to have changes in nervous system and immune function. Higher doses of Heptachlor when exposed to newborn animals caused decrease in body weight and death.

Hexachlorobenzene, a fungicide now banned globally under the Stockholm Convention

Mirex, is a chlorinated hydrocarbon that was commercialized as an insecticide and later banned because of its impact on the environment.

toxaphene is an insecticide. It is a mixture of closely related substances whose use is now banned in most of the world due to concerns of toxicity.

Since then, this list has generally been accepted to include such substances as carcinogenic polycyclic aromatic hydrocarbons (PAHs) and certain brominated flame-retardants, as well as some organometallic compounds such as tributyltin (TBT).

Thanks to Wikipedia and the worldbank