There has been a lot of debate about global warming. On my part, I am doubtful that the industrialization of the human race is solely responsible for the warming of our atmosphere. After all, the earth has gone through many cooling and warming trends over the course of its existence and most of those have occurred before man industrialized. My current vote for most likely culprit is sunspots.
Historically speaking, when sunspot activity is high, global temperatures are higher. When the sun is quiescent, global temperatures are lower. According to those in the know, we are heading shortly into a quiescent period with attendant cooling which, according to some, should nicely offset any rise in temperature that rising carbon dioxide levels may cause. Not that I consider that a “cure,” it will just give us some time to get our act together.
So, what has this got to do with Persistent Organic Pollutants? When I think about the impact humanity has had upon the global environment, these (not CO2) come to my mind.
In his book, “Exposed: The Toxic Chemistry of Everyday Products and What’s at Stake for American Power,” Mark Schapiro addresses POPS in his fourth chapter. He discusses the “dirty dozen”, dubbed that about twenty years ago by the NGO Pesticide Action Network. They are: chlordane, heptachlor, aldrin, dieldrin, mirex, DDT, hexachlorobenzene, toxaphene, polychlorinated biphenyls (PCBs), dioxins and furans. In Schapiro’s words, “All act like light switches of toxicity upon the human body – potent neurotoxins and carcinogens that most countries in the world had agreed to kick out of global commerce.”
I believe that POPS, like those listed above and others, pose the human race a far greater risk than does global warming. The kinds of chemicals and amounts that are dumped into our global environment on a daily basis are frightening. I think that this issue is much more important than global warming and I am just cynical enough to think that perhaps global warming is pushed at us so hard to keep us from focusing on a truly bad situation; one clearly entirely of our own making.
Because the “dirty dozen” is a lot of territory to cover and the main thrust of Schapiro’s book is political, it quickly became apparent that he really wasn’t going to provide a lot of information about those chemicals. I decided to do a little research of my own. Unlike with my previous article about phthalates, the first page of a Google search did not turn up site after site that was all in favor of these chemicals. I chose one that we have all heard about…dioxin, and one with which I was not familiar…mirex.
Mirex has been around a long time. It was first synthesized in 1946, but was not used in pesticides until 1955. It is a stomach insecticide. That means that the insect must ingest it to be affected by it. The first use was focused on the Southeastern United States to combat fire ants. Approximately 550,000 pounds of mirex was applied to farm fields during 1962 to 1975. All uses of mirex as a pesticide were banned in 1978; however, it is still used as a flame-retardant in plastics, rubber, paint, paper and electronics. It has also been used to fight leaf cutters in South America, harvester termites in South Africa and mealy bugs on pineapple in Hawaii.
Effects on organisms combined with its persistence suggest that mirex presents a long-term hazard for the environment. In 1979, the IARC (International Agency for Research on Cancer) evaluated mirex and decided that “there is sufficient evidence for its carcinogenicity to mice and rats. In the absence of adequate data in humans, based on above result it can be said that it has carcinogenic risk to humans.”
Mirex is very stable and wide spread in the environment. In fact it is one of the most stable of the organochlorine insecticides. The article I read says that mirex induces pervasive and long-term physiological and biological disorders in vertebrates (that includes humans). It is both accumulated and biomagnified. That means that it persists (mainly in fat as it has low water solubility) and the higher up the food chain you go, the higher levels may be present. It is transported across the placenta and affects developing fetuses. It is also excreted in mother’s milk.
Mirex is a problem that we have directly created for ourselves. Dioxin on the other hand is more like a really unfortunate accident of industrialization.
To quote the first paragraph from the World Health Organization’s website (www.who.int/mediacentre/factsheets/fs225/en/) “Dioxins are environmental pollutants. They have the dubious distinction of belonging to the “dirty dozen” – a group of dangerous chemicals known as persistent organic pollutants. Dioxins are of concern because of their highly toxic potential. Experiments have shown they affect a number of organs and systems. 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 is the concentration of dioxins.”
The chemical name for dioxin is very long and is usually abbreviated TCDD, and this form is considered to be the most toxic and the standard against which all other dioxins are measured. The “family” of dioxins also includes PCBs, which act very much like dioxins. Approximately 419 dioxin compounds have been identified, but only about 30 of the dioxin related compounds are thought to have significant toxicity. I think that 30 are too many.
Dioxins are mainly the result of industrial processes, but they do occur naturally from volcanic eruptions and forest fires. They are the by-product of smelting, chlorine bleaching of paper pulp and the manufacturing of some herbicides and pesticides. Solid waste and medical waste incinerators are the worst culprits, however, due to incomplete burning. It is also associated with the production of polyvinyl chloride plastics. TCDD was used in Agent Orange. In January of 2001, the U.S. National Toxicology Program upgraded TCDD from “reasonably anticipated to be a human carcinogen” to “known to be a human carcinogen.” This was somewhat behind the IARC’s assessment.
In instances of short-term exposure of humans to high levels of dioxins, skin lesions such as chloracne and patchy darkening of the skin occur. Alterations in liver function have also been recorded. One famous and deliberate poisoning of a human with dioxins occurred in 2004 when the President of the Ukraine had his face disfigured by chloracne.
Long-term exposure carries more risks. It is linked to impairment of the immune system, the developing nervous system, the endocrine (glands) system and reproductive functions. TCDD was evaluated by WHO’s IARC in 1997, when it was classified as a known carcinogen in humans.
With our current state of affairs and industrialization, dioxins are inescapable and omnipresent. Everyone has what they call “background exposure” and a certain level of dioxins in the body leading to what is called “body burden.”
As humans, our major source of exposure to dioxins is from our diet. The typical North American eating a typical North American diet can expect to receive, on average, 119 picograms of dioxins daily. Now, a picogram is a very small amount (a pg is about one-trillionth of a gram and one gram is about 1/40th of an ounce), but the extreme toxicity of dioxins must be taken into account. Of that 119 pg, 38% comes from eating beef, 24.1% from dairy, 17.6% from milk, 12.9% from chicken, 12.2% from pork, 7.8% from fish, 4.1% from eggs, 2.2% from breathing, 0.8% from eating dirt (it happens) and the contribution from drinking water is negligible. The farm-raised fresh water fish used in the study were fed a diet of meat, which is why that percentage is as high as it is. Wild, ocean-going fish have much lower levels and contribute less to the burden.
In studies to determine levels of dioxins in humans, it was learned that a vegan diet (eating absolutely no meat or dairy products) produced the lowest levels of dioxins in the body. I have often been heard to say that I would be a vegetarian (mostly for ethical reasons) except that I really don’t digest legumes at all well. Getting all the necessary proteins in your diet to maintain good health without eating meat and/or dairy products can be very difficult.
It would be best to put stringent controls on dioxin emissions and keep them out of our environment as much as possible so that they are not biomagnified in the foods that we eat. That is not to mention what it must also be doing to our wildlife.
Solid wastes that are burned must be incinerated more thoroughly and there are plenty of guidelines for doing this. Now, I like my white printer paper to be white, but if dioxins could be significantly reduced by not bleaching paper pulp, then I would accept it as yellow or brown. As for herbicides and pesticides, there is no way, we are told, that we can produce the amount of food that we need to feed the United States without them. It’s too labor intensive otherwise. I’m not advocating a return to a pre-industrial lifestyle, but I have to tell you, I may never look at that pot of spaghetti sauce with hamburger that I have simmering on the stove right now quite the same way. Even so, I don’t think that wild-caught salmon spaghetti sauce is anywhere in my future.
Of course, we could all become vegan and that would reduce our load of dioxins. I don’t honestly think that’s practical. But what about being vegan one day a week? Skipping all animal flesh and dairy products for one day a week shouldn’t be too hard. Also, eating more wild-caught, salt water fish would help. One article also recommended eating only low-fat or non-fat dairy products (the dioxins accumulate in the fat) and skipping butter all together.
It wouldn’t be so bad if it were just mirex and dioxins that we were talking about. But it’s not. That’s why we owe it to ourselves to take a hard look at what we are doing to ourselves and our environment. My husband and I have replaced all of our incandescent light bulbs with compact fluorescent light bulbs and I think that is good. But I still think the more important issue is not green house gases, but the load of chemicals we “dump” on ourselves each and every day.