Dioxins

Introduction

Dioxins are environmental pollutants. They belong to the so-called “dirty dozen” – group of hazardous chemicals known as persistent organic pollutants (POPs). They are of great concern because of their highly toxic potential. Experiments have shown they affect a number of organs and systems. Once dioxins enter the body, they last 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 7 to 11 years. In the environment, dioxins tend to accumulate in the food chain. The higher an animal is in the food chain, the higher the concentration of dioxins.

The normal response of the human immune system is a highly fused process in which signals generated though early recognition by the innate immune system has significant impact of the subsequent adaptive response. This integration ensures that the effector mechanisms triggered are effectively targeted towards the infectious agent in question. The immune system has an essential role: It protects our body from harmful substances, germs and cell changes that could make us ill. It is made up of various organs, cells and proteins. As long as our immune system is running smoothly, we don’t notice that it’s there. But if it stops working properly – because it’s weak or can’t fight particularly aggressive germs – we get ill. Germs that our body has never encountered before are also likely to make us ill. Some germs will only make us ill the first time we come into contact with them. These include childhood diseases like chickenpox. Without an immune system, we would have no way to fight harmful things that enter our body from the outside or harmful changes that occur inside our body. The main tasks of the body’s immune system are; fighting disease-causing germs (pathogens) like bacteria, viruses, parasites or fungi and removing them from the body, recognizing and neutralizing harmful substances from the environment and  fighting disease-causing changes in the body such as cancer cells.

Human exposure to dioxins has been associated with a range of toxic effects, including immunotoxicity, developmental and neurodevelopmental effects, and changes in thyroid and steroid hormones and reproductive function. Developmental effects are the most sensitive health end-point making children, particularly breastfed infants, the population most at risk. “Dioxins and dioxin-like substances” refer to polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs.

Dioxins are by-products of industrial processes but can also result from natural processes, such as volcanic eruptions and forest fires. They are mainly unwanted by-products of a wide range of manufacturing processes such as smelting, chlorine bleaching of paper pulp and the manufacturing of some herbicides and pesticides. Regarding dioxin release into the environment, uncontrolled waste incinerators are often the worst culprits, due to incomplete burning. Although formation of dioxins is local, environmental distribution is global. Dioxins are found worldwide in the environment. The highest levels of these compounds are found in soils, sediments and food, especially dairy products, meat, fish and shellfish. Very low levels are found in plants, water and air. Extensive stores of PCB-based waste industrial oils, many with high levels of PCDFs, exist throughout the world.

Long-term storage and unethical disposal of this material result to the release of dioxin into the environment and the contamination of human and animal food supplies. PCB-based waste is not easily disposable without contamination of the environment and human populations. Such material needs to be treated as hazardous waste and is best destroyed by high temperature incineration in specialized facilities.

Short-term subjection of humans to high levels of dioxins can result to skin lesions, such as chloracne and patchy darkening of the skin, and altered liver function.

 Long-term exposure is connected to impairment of the immune system, the developing nervous system, the endocrine system and reproductive functions.

 Dioxin can get into drinking water from: Air emissions from waste incineration and other combustion, with subsequent deposition to lakes and reservoirs. Deposition from air to soils that erode into surface waters used for drinking water discharges into water from chemical factories. Dioxins are highly toxic and can cause cancer, reproductive and developmental problems, damage to the immune system, and can interfere with hormones.

Due to the ubiquitous nature of dioxins, all people have background exposure and a certain level of dioxins in the body. The developing fetus is highly sensitive to dioxin exposure. Newborn, with rapidly developing organ systems, can also be more vulnerable to certain effects. Many people have been exposed to higher levels of dioxins because of their diet such as high consumers of fish (More than 90% of typical human exposure is estimated by EPA to be through the intake of animal fats, mainly meat, dairy products, fish, and shellfish) or their occupation at work in the pulp and paper industry, in incineration plants, and at hazardous waste sites.  

The dioxin (2,3,7,8- tetrachlorodibenzo para dioxin (TCDD) is a known cancer-causing agent.in addition dioxin exposure has been linked to a number of  other diseases such as type 2 diabetes, ischemic heart disease and chloracne.

Dioxins have also caused developmental problems in children, infertility problems in adults resulting to miscarriages, damage of the immune system and interference with the hormones in the US.

 Proper incineration of contaminated material is the best available method of preventing and controlling exposure to dioxins. It can also destroy PCB-based waste oils. The incineration process requires high temperatures, over 850°C. For the destruction of large For the  amounts of contaminated material, even higher temperatures – 1000°C or more – are required. Prevention or reduction of human exposure is best done via source-directed measures, i.e. strict control of industrial processes to reduce formation of dioxins as much as possible. This is the responsibility of national governments. The Codex Aliment Arius Commission adopted a Code of Practice for Source Directed Measures to Reduce Contamination of Foods with Chemicals.

If than 90% of human exposure to dioxins is through the food supply, mainly meat and dairy products, fish and shellfish then protecting the food supply is critical. In addition to source directed measures to reduce dioxin emissions, secondary contamination of the food supply must be avoided throughout the food chain. Good controls and practices during primary production, processing, distribution and sale are all essential in the production of safe food. Contaminated animal feed is often the root-cause of food contamination therefore food and feed contamination monitoring systems have been put in place to ensure that tolerance levels are not exceeded. It is the role of national governments to monitor the safety of food supply and to take action to protect public health.

Consumers have also taken the initiative to lower their exposure to dioxin compounds by trimming fat from meat and consuming low fat dairy products dioxin. Also, eating a balanced diet (including adequate amounts of fruits, vegetables and cereals) has helped to avoid excessive exposure from a single source. This is a long-term strategy to reduce body burdens and is probably most relevant for girls and young women to reduce exposure of the developing fetus and when breastfeeding infants later on in life. However, the possibility for consumers to reduce their own exposure is somewhat limited. “The old adage, ` you are what you eat’ is a touchstone for many aspects of human health,” said Laurence but in terms of the body’s ability to fight off infections, this paper suggests that, to a certain extent, you may be also what your great grandmother ate.

Refferences

Fromme H Albretch M, Appel M, Hilger B, Volkel W, Liebl B, et al. (2015) PCBs, PCDD/Fs in blood samples of rural population in South Germany.Int J Hyg Environ Health 218(1): 41-6

Manning TM, Roach AC, EdgeKj, Ferrell Dj (2017) Levels of PCDD/Fs and dioxin-like PCBs in seafood from Sydney Haerbour,Australia.Environ Pollut.;224:590-6 Brandes R, Lang F, Schmidt R (Ed). Physiologie des Menschen: mit Pathophysiologie. Berlin: Springer; (2019)

Home/Newsroom/Fact sheets/Detail/Dioxins and their effects on human heath (2016)

Roberta Attanassio, Environmental Toxins and Damage to the Immune System: Trans generational Effects.