This post is taken directly from an assignment for a class toward fulfillment of my Master of Public Health, Environmental Influences on Human Health. I seek to educate about dioxins, which are found in very high concentrations in human breastmilk. Dioxin exposure (perhaps in utero) has been shown to have a profound effect on mammary gland development — rendering exclusive breastfeeding impossible in some cases. Since the practice of incinerating solid waste has declined, so have dioxin levels in our environment; however, today’s new mothers were babies before this practice was changed. While the prevalence of mammary hypoplasia is not epidemic, I see more of it in my practice today than statistics suggest I should, and I wonder whether environmental contaminants play a significant role in this phenomenon.
Dioxins are undesired by-products of chemical, manufacturing, and combustion processes related to industry in the presence of chlorine. Processes that can result in the release of dioxins include bleaching paper pulp, heating mixtures of chlorine and organic compounds, incinerating chlorine-containing materials, and the production of pesticides, herbicides, and certain wood preservatives. Incomplete combustion of wood products and industrial/municipal wastes, such as when incineration was the standard method of trash management, also results in dioxin formation. Since methods of incineration of solid waste have changed, dioxin levels have gone down in the last quarter-century, but because dioxins are stable, non-water soluble compounds, once they are in the soil, they are difficult to get rid of (Moore, 2007).
There are 419 compounds that are identified as dioxins; of these, 30 are considered to be of significant toxicity (World Health Organization, 2010). The term “dioxins” refers to chemically/structurally related chemicals:
- 2,3,7,8-tetrachlorodibenzo para dioxin (TCDD)
- polychlorinated dibenzo para dioxin (PCDD)
- polychlorinated dibenzofuran (PCDF)
- polychlorinated biphenyls (PBB’s) are dioxin-like with similar toxic properties, and are therefore categorized with the dioxin family
The most toxic of these are the TCDD’s.
Dioxins are among the most toxic substances to humans, potentially causing reproductive and developmental problems, damage to the immune system, and cancer. In 1997, the World Health Organization’s International Agency for Research on Cancer declared that TCDD is a class 1 carcinogen, known to cause cancer in humans (Moore, 2007). At levels far below those which are believed to cause cancer, dioxin exposure has been linked to reduced fertility (female and male), diabetes, and endocrine system disruptions (Environmental Justice Network, 2011). A known endocrine disruptor, dioxin can block the action of estrogen in the body, change the number of estrogen receptor sites, alter the rate of production of hormones in the body, replace hormones on the carrier proteins in the bloodstream, and cause adverse health effects (some barely noticeable, others very severe) by making some or all of the naturally occurring hormones in the body unavailable for use (Moore, 2007). Dioxins, while not themselves lethal, can cause health problems and are the cause of a skin condition called chloracne, which occurs at very high levels of exposure (U.S. Department of Health and Human Services, Food and Drug Administration, 2010). Because of their stability and persistence, dioxins do not break down and are difficult for the body to excrete; therefore, they bioaccumulate and are stored in fat tissue, creating a body burden of toxicity. The half-life of dioxin compounds is estimated to be 7 to 11 years, representing a significant, long-term effect on the environment and the food chain (WHO, 2010). This is of particular concern to women who become mothers; dioxin crosses the placenta, resulting in contamination of a baby before he is born. Additionally, dioxin is stored in breast tissue and can be found in extremely high levels in the breastmilk of human mothers, especially those who consume a lot of animal foods or who live or work in/near the pulp and paper industry, incineration plants, or at hazardous waste sites (WHO, 2010). It is important to note, however, that the benefits associated with breastfeeding far outweigh the potential risks associated with dioxin exposure (U.S. Environmental Protection Agency, 2011).
As 90% of human dioxin exposure is through food (WHO, 2010), this is obviously the route of exposure that we must address. However, in order to enter our food supply, dioxin must first be produced by the processes mentioned above, after which time it enters the air, water, and soil. Once there, it is many years before dioxin begins to break down; therefore, animals are exposed to dioxin compounds in the food they eat, which are sequestered in their body fat, and, when humans consume these animals and their milk (and, of course, their fat), the concentration of dioxins is very high. As mentioned previously, this is of profound importance to babies in utero, who receive dioxins that cross their mothers’ placentas, and, once born, consume the milk at the top of the food chain, which carries the highest concentration of dioxin. This is problematic because the consumption of milk is extremely high relative to the infant’s body weight.
Studies have indicated that dioxin exposure can affect mammary gland development in mammals, including humans (see Rudel, et. al; Fenton, et. al; and Markey, et. al in references). In a culture that recognizes alternate methods of feeding as the norm, impact on mammary gland development may not serve as a huge motivator in changing policy to reduce dioxin exposure. No functioning breasts? Just bottle-feed! Here in the United States, where the public health message is definitely to breastfeed, mothers who find themselves with insufficient glandular tissue/mammary hypoplasia are searching for answers — they want to know why their bodies failed to provide sole nourishment for their babies.
In dioxin exposure, perhaps we have found a fixable reason for the incidence of IGT in mothers? If so, policy changes to eliminate the production of dioxins may lower the incidence of IGT population-wide. In the interim, I work to find methods of maximizing milk production for mothers who wish to provide their milk, even if only a small amount, for their babies … but this research could potentially open many important discussions about the implications of the toxins in our environment.
Because dioxins are not water-soluble, when they enter a river or a stream, they are absorbed by fatty fish, which then become unsafe to eat because the concentrations of dioxins in these fish are so high. When cows are fed products that have been treated with pesticides, herbicides, or that are made from animal fats, the dioxins in those foods are stored in the fat, which is passed to humans, concentrated in the meat and milk of those cattle. The possible exception to this is cattle that are vegetarian and completely grass-fed in an area where not more than naturally-occurring dioxin is found (areas away from industrial centers, pesticide and herbicide runoff, or affected by highly contaminated rainwater). While dioxin formation is local to such areas, the distribution of dioxin is global (WHO, 2010).
The foods that are most highly contaminated with dioxins are:
- dairy products (cheese, ice cream, yogurt)
(Schecter et al., 2005)
Clearly, those who are concerned with dioxin’s potential untoward health effects can significantly reduce their personal/family’s exposure by adopting a vegan diet, excluding all animal products. I state this first because it is absolutely the most effective means an individual can adopt to reduce dioxin exposure in his or her life. Another measure, consistent with U.S. governmental recommendations, is to reduce the amount of animal fat in one’s diet, resulting in a lower exposure, but not elimination of dioxin. Using skim milk and consuming lowfat versions of dairy products will lower dioxin exposure, but some theorize that our bodies need the full-fat versions, preferably from locally-produced sources. As mentioned previously, consumption of locally-pastured, grass-fed beef and milk, in areas away from current or former dioxin-producing processes, can also help to reduce personal levels of dioxin exposure. There is continuing governmental monitoring of dioxin levels in our food supply, however, in my opinion, not enough is being done to clean up the meat and dairy products that are widely available to Americans who may not have access to or the ability to afford locally-produced, sustainable alternatives that are lower in dioxin and other harmful chemicals. In this arena, however, dioxin is only a drop in the bucket full of issues that exist, along with genetically-modified organisms (GMO’s) in our food, federal subsidies for commodity crops like corn and soybeans that are incorporated into countless processed “food” items, and the use of ammonia and other chemical-containing fillers in factory-produced meats. These fillers, while intended to combat the risk of E.Coli and other bacteria, are also part of the dietary dioxin load carried by the average American, and potentially cause more harm than good. Adopting a vegan diet may be the answer to the dioxin question, as well as other questions, for many in our population, but this will not be practical for or preferred by all.
Because dioxins are produced in the presence of chlorine, reducing personal use of bleached products, such as tampons and coffee filters, and bleach itself, not only reduces the amount of dioxin an individual might be exposed to, it reduces the demand for these products, which cuts the need for manufacture and disposal of them. Unbleached items may not be as visually appealing to our “bright and shiny” sensibilities, but are less likely to harm us or the environment around us. Oxygen bleach works well in place of chlorine bleach for washing clothes; white vinegar, baking soda, and lemons are excellent non-bleach alternatives for household cleaning purposes. Families are exposed to fewer dangerous chemicals, and less dioxin is released into the water treatment systems.
On the community level, regulation of pesticide and herbicide use can impact the amount of dioxin that is released into the environment. Similar to household use of chlorine-bleached products, when pesticides and herbicides are passed up in favor of environmentally-sustainable methods of pest and weed control, the demand for production of these substances is reduced in addition to the lower proximate levels of dioxins. Pulling dandelions with a device designed for this purpose, allowing grass to grow longer (to crowd out weeds), and using food-grade substances such as clove oil for weed control reduce our exposure to toxins. Strategic planting of gardens and crops and allowing natural predators to take care of pests can help eliminate our need for pesticides on our food. Along the same lines, individuals who choose organically or locally grown produce send a clear message that we do not want to consume harmful chemicals in our food.
It is important to note that, while we can reduce man-made release of dioxin, dioxin has existed on the planet for longer than humans have, and such natural events as forest fires and volcanoes will always be sources of dioxin that humans will be exposed to (WHO, 2010).
Plastics that are made from PVC (polyvinyl chloride) are implicated in dioxin release in their production, and when these plastics are burned intentionally or accidentally in home, vehicle, and landfill fires. PVC production is increasing worldwide, and is now the world’s largest use of industrial chlorine, accounting for 30% of the world’s chlorine production. PVC is used at an alarming rate in the production of building materials such as pipes and window frames, and in home products such as shower curtains and vinyl flooring. PVC plastics are pervasive in our society as office supplies, furniture, credit cards, and other common consumer items. In addition to the dioxins released in the production of PVC plastics, their use is problematic, as plasticizers are not bound to the materials and can leach out of the items into the air where they are being used. PVC materials are difficult and expensive to recycle, because more PVC is needed to recycle PVC into a new product of the same quality. The disposal of PVC creates an environmental hazard; if incinerated, PVC releases large amounts of dioxins and other chemicals into the air. In improperly constructed landfills, the plasticizers in PVC can leach into the surrounding ground and soil, resulting in long-term contamination (Greenpeace, 1997). If dioxin reduction is a global priority, the manufacture, use, and disposal of PVC materials cannot continue as it currently occurs.
Globally, there is good news for reducing our exposure to dioxin. The United States and other countries have taken measures and implemented policies to enforce the reduction of dioxin production. Beginning in the 1970’s, changes to incineration procedures were put into practice after the Clean Air Act was passed, and further controls on the major sources of industrial dioxin release were implemented in 1987. Emission levels of dioxins have decreased 90% since 1987, which has resulted in lower exposures and amounts of stored dioxins in humans (U.S. Environmental Protection Agency, 2011). However, since dioxins are so persistent and take many years to break down and be eliminated, continued efforts are necessary to reduce worldwide dioxin production and release, and additional time is required to allow the existing presence of dioxins to decrease. Because of this time lag, even if current exposure levels do not decrease significantly, it is expected that the amount of dioxins built up in our bodies will continue to decline (Chlorine Chemistry Division of the American Chemistry Council, 2011).
While dioxin continues to be an environmental threat to human health, the reduction in dioxin exposure that has taken place over the last few decades has positively impacted humans across the planet with a corresponding decline in the body burden borne by each individual, especially in areas were industrial centers were major producers of dioxins. Control over the practice of incineration and policies that regulate the production and use of certain pesticides and herbicides have been moves in the right direction, but because of dioxin’s persistence in the environment, time must elapse before the impact of these regulatory measures can be realized. PVC production, use, and disposal remains the greatest obstacle to true dioxin reduction; perhaps if pressure is put on policymakers by informed consumers, change will occur as it did with regard to incinerators, which were previously the largest source of dioxin release.
Chlorine Chemistry Division of the American Chemistry Council. (2011). DioxinFacts.org: Dioxin exposures and body levels fall dramatically. Retrieved from http://dioxinfacts.org/dioxin_health/dioxin_tissues/dioxin_exposures.html
Costner, P. (2001). Chlorine, combustion, and dioxins: Does reducing chlorine in wastes decrease dioxin formation in waste incinerators? Greenpeace: Retrieved from http://archive.greenpeace.org/toxics/reports/chlorineindioxinout.pdf
Environmental Justice Network. (2011). Dioxin Home Page. Retrieved from http://www.ejnet.org/dioxin/
Fenton, S. E., Hamm, J. T., Birnbaum, L. S., & Youngblood, G. L. (2002). Persistent abnormalities in the rat mammary gland following gestational and lactational exposure to 2, 3, 7, 8,-tetrochlorodibenzo-p-dioxin (TCDD). Toxicological Sciences, 67(1), 63-74.
Greenpeace. (1997). PVC – The poison plastic. Retrieved from http://archive.greenpeace.org/toxics/html/content/pvc1.html
Markey, C. M., Rubin, B. S., Soto, A. M., & Sonnenschien, C. (2003). Endocrine disruptors: from Wingspread to environmental developmental biology. Steroid Biochemistry and Molecular Biology, 83, 235-244.
Moore, G. S. (2007). Living With the Earth: Concepts in Environmental Health Science. Boca Raton, FL: Taylor & Francis. p. 201-204.
Rudel, R. A., Fenton, S. E., Ackerman, J. M., Euling, S. Y., Makris, S. L. (2011). Environmental exposures and mammary gland development: State of the science, public health implications, and research recommendations. Environ Health Perspect 119(8): doi:10.1289/ehp.1002864
Schecter, A., Cramer, P., Boggess, K., Stanley, J., Papke, O., Olson, J., … Schmitz, M. (2001). Intake of dioxins and related compounds from food in the U. S. population. Journal of Toxicology and Environmental Health, 63, p. 1-18. Retrieved from http://www.ejnet.org/dioxin/dioxininfood.pdf
U. S. Department of Health and Human Services, Food and Drug Administration. (2010).Questions and answers about dioxins. Retrieved from http://www.fda.gov/Food/FoodSafety/FoodContaminantsAdulteration/ChemicalContaminants/DioxinsPCBs/ucm077524.htm#g10
U. S. Environental Protection Agency. (2011). Persistent Bioaccumulative and Toxic (PBT) Chemical Program: Dioxins and Furans. Retrieved from http://www.epa.gov/pbt/pubs/dioxins.htm
Vorderstrasse, B.A., Fenton, S.E., Bohn, A.A., Cundiff, J.A., & Lawrence, B.P. (2004). A novel effect of dioxin: Exposure during pregnancy severely impairs mammary gland differentiation. Toxicological Sciences, 78(2), 248-57.
World Health Organization. (2010). Dioxins and their effects on human health (Fact sheet No. 225). Retrieved from http://www.who.int/mediacentre/factsheets/fs225/en/