Persistent organic pollutant
The effect of POPs on human and environmental health was discussed, with intention to eliminate or severely restrict their production, by the international community at the Stockholm Convention on Persistent Organic Pollutants in 2001.
[2] The "dirty dozen" POPs identified by the Stockholm Convention include aldrin, chlordane, dieldrin, endrin, heptachlor, HCB, mirex, toxaphene, PCBs, DDT, dioxins, and polychlorinated dibenzofurans.
[3][4][5][6] Halogenated compounds also exhibit great stability reflecting the nonreactivity of C-Cl bonds toward hydrolysis and photolytic degradation.
[1] They exert their negative effects on the environment through two processes: long range transport, which allows them to travel far from their source, and bioaccumulation, which reconcentrates these chemical compounds to potentially dangerous levels.
[8] POPs enter the gas phase under certain environmental temperatures and volatilize from soils, vegetation, and bodies of water into the atmosphere, resisting breakdown reactions in the air, to travel long distances before being re-deposited.
In adsorbed form it is – as opposed to the gas phase – protected from photo-oxidation, i.e. direct photolysis as well as oxidation by OH radicals or ozone.
[9][17] This increase in concentration is called biomagnification, which is where organisms higher up in the food chain have a greater accumulation of POPs.
[18] Bioaccumulation and long-range transport are the reason why POPs can accumulate in organisms like whales, even in remote areas like Antarctica.
The convention seeks to study and then judge whether or not a number of chemicals that have been developed with advances in technology and science can be categorized as POPs.
[2][21][23] Since 2001, this list has been expanded to include some polycyclic aromatic hydrocarbons (PAHs), brominated flame retardants, and other compounds.
Low level exposure to POPs during critical developmental periods of fetus, newborn and child can have a lasting effect throughout their lifespan.
A 2002 study[39] summarizes data on endocrine disruption and health complications from exposure to POPs during critical developmental stages in an organism's lifespan.
The study aimed to answer the question whether or not chronic, low level exposure to POPs can have a health impact on the endocrine system and development of organisms from different species.
The study found that exposure of POPs during a critical developmental time frame can produce a permanent changes in the organisms path of development.
Exposure of POPs during non-critical developmental time frames may not lead to detectable diseases and health complications later in their life.
The study stated that POP exposure can lead to negative health effects especially in the male reproductive system, such as decreased sperm quality and quantity, altered sex ratio and early puberty onset.
[46] In 2022, levels of at least four perfluoroalkyl acids (PFAAs) in rain water worldwide greatly exceeded the EPA's lifetime drinking water health advisories as well as comparable Danish, Dutch, and European Union safety standards, leading to the conclusion that "the global spread of these four PFAAs in the atmosphere has led to the planetary boundary for chemical pollution being exceeded".
