Environmental Health: Health effects of low-concentration POPs

Environmental Health: Health effects of low-concentration POPs

■  Body Storage of POPs

The toxicity of individual chemicals belonging to POPs at high concentrations has been well known for a long time. Recently, there's been growing concern about the health risks associated with chronic exposure to low concentrations of POPs in the environment. Human exposure to POPs typically involves exposure to complex mixtures of hundreds of chemicals throughout life, even though the concentration of each individual chemical is very low.

POPs are known to easily pass through the placenta, meaning they can transfer from a pregnant woman's blood to the fetus. After birth, exposure continues through breast milk and food, especially animal products. Once in the body, POPs, which are highly fat-soluble, mainly accumulate in fat tissue. They are continuously released into the bloodstream through the breakdown of fat, reaching various organs. While adipose tissue helps protect against acute toxicity from POPs, it also serves as a source of chronic exposure to these pollutants. Additionally, POPs are external factors that can contribute to obesity and disrupt the structure and function of adipose tissue.

< POPs and adipose tissue: Redrawn La Merrill et al>

 

■  POPs and non-communiable diseases 

The U.S. National Toxicology Program (NTP) determined that there is sufficient evidence to establish a connection between certain organochlorine POPs and type 2 diabetes. Additionally, numerous studies have reported a link between cardiovascular disease and metabolic syndrome.

Outcome	Author (Year)	Study design	Area	Results
cardiovascular-related deaths	Kim et al. (2015)	Cross-sectional study	USA	In a study of 633 elderly individuals aged over 70, using data from the National Health and Nutrition Examination Survey, it was found that PCBs and organochlorine pesticides were linked to an increased risk of death overall and a higher risk of cardiovascular-related deaths among elderly people with low body fat.
Type 2 diabetes	Jaacks and Staimez. (2015)	meta-analysis		There is a positive correlation between diabetes and the concentration of POPs (PCDD/Fs, PCBs, DDT, DDE, oxychlordane, trans-nonachlor, hexachlorobenzene, hexachlorocyclohexane) in the blood.
	Lee et al. (2006)	Cross-sectional study	USA	A significant dose-response relationship was found between blood levels of persistent organic pollutants such as dioxins, chlorinated biphenyls, and organophosphates, and the occurrence of diabetes.
Metabolic syndrome	Lee et al. (2007)	Cross-sectional study	USA	Organochlorine pesticides demonstrate a highly significant association with metabolic syndrome, with adjusted odds ratios (ORs) according to quantiles of 1.0, 1.5, 2.3, and 5.3.

 

■  POPs and cancers 

To date, investigations into the correlation between POPs and cancer have largely relied on occupational cohorts, revealing a connection between exposure to elevated levels of POPs and cancer incidence. Recent studies have begun to explore the relationship between environmental POPs exposure and cancer incidence. Even after 20-30 years since the ban on POPs, these pollutants remain detectable in serum samples, suggesting that background exposure to POPs could increase the risk of developing lung and colon cancer. Specifically, PCBs have been associated with the development of lung and colon cancer, irrespective of their chlorination degree, substitution pattern, or receptor binding affinity. Furthermore, the European Prospective Investigation into Cancer and Nutrition (EPIC) study reported a correlation between environmental POPs exposure and pancreatic cancer.

 

■   References

• Curtis D. Klaassen. Casarett and Doull’s Toxicology. McGraw Hill / Medical; 9th edition (2018)
• Stockholm Convention - Home page – POPs: https://chm.pops.int/ Access date: 2024-03-03
• La Merrill M, Emond C, Kim MJ, Antignac JP, … Barouki R. Toxicological function of adipose tissue: focus on persistent organic pollutants. Environ Health Perspect. 2013 Feb;121(2):162-9.
• Taylor KW, Novak RF, …., Lind L. Evaluation of the association between persistent organic pollutants (POPs) and diabetes in epidemiological studies: a national toxicology program workshop review. Environ Health Perspect. 2013 Jul;121(7):774-83.
• Park EY, Park E, Kim J, Oh JK, Kim B, Hong YC, Lim MK. Impact of environmental exposure to persistent organic pollutants on lung cancer risk. Environ Int. 2020 Oct;143:105925.
• Park EY, Kim J, Park E, Oh JK, Kim B, Lim MK. Serum concentrations of persistent organic pollutants and colorectal cancer risk: A case-cohort study within Korean National Cancer Center Community (KNCCC) cohort. Chemosphere. 2021 May;271:129596.
• Palli D, Grioni S, Tumino R, …. Vineis P. Plasma concentrations of persistent organic pollutants and pancreatic cancer risk. Int J Epidemiol. 2022 May 9;51(2):479-490.