This week, delegates from 130 countries met in Punta del Este, Uruguay to discuss an
international treaty:
The Stockholm Convention is a global treaty to protect human health and the environment from persistent organic pollutants (POPs). POPs are chemicals that remain intact in the environment for long periods, become widely distributed geographically, accumulate in the fatty tissue of living organisms and are toxic to humans and wildlife. POPs circulate globally and can cause damage wherever they travel. In implementing the Convention, Governments will take measures to eliminate or reduce the release of POPs into the environment.
The 19th session of the UNEP's Governing Council decided that something had to be done worldwide about POPS; in December 2000, the finishing touches were put on the Stockholm Convention, and in 2001, the Convention was formally adopted.
To date, 151 countries have signed the Convention; however, not all of them have ratified it. The two largest industrialized countries that have not ratified the Convention are the U.S. and Russia.
So you're thinking "Who the hell cares? What's the big deal? It's not like it's global warming or anything."
Well, I have a few acronyms for you to think about. Click each one to see the significance:
• DDT
• TCDD (as well as this example, and this one)
• PCBs
Those are just three of the "dirty dozen", i.e. twelve POPs that have been banned by the Stockholm Convention, and for good reason.
Continued below the fold...
How are POPs defined?
According to the United Nations Environment Programme, persistent organic pollutants, or POPs, are categorized as such based on a number of criteria:
Persistence: The ability to resist degradation in various media, e.g. air, soil, water, sediment, measured as half-life of the substance in the medium.
Bioaccumulation; the ability of a chemical to accumulate in living tissues to levels higher than those in the surrounding environment, expressed as the quotient between the concentration in the target tissue and the environmental concentration.
Toxicity; the ability of a chemical to cause injury to man or the environment.
Volatility; the ability of a chemical to vaporise into air, measured in Pascals. Substances with a volatility of <1000 Pascals are of primary concern.
Long-range transport; as evidenced e.g. by measurements of the chemical in biota in remote regions.
Bioavailability; based on field data or expert judgement has also been proposed as a criterion for identifying POPs.
The atmospheric half-life of any "dirty dozen" chemical is around two days. In water, soil, and sediment, the half-life of any "dirty dozen" depends on a multitude of factors, but generally (according to the link I gave you) they are anywhere between months to several years. They hang around, in other words.
As for bioaccumulation, all of these chemicals concentrate in living tissue (fat, etc.).
Regarding toxicity, the link I gave you also has this paragraph:
There is at present no established criterion for toxicity in international negotiations, and it is unlikely that there will be one. While the other parameters are essentially one-dimensional, toxicity is multidimensional and multifaceted. Any assessment of toxicity requires an assessment of dose. Substances of moderate toxicity may cause concern because they are present in significant doses. Chronic and irreversible effects are also assessed differently from acute and transient effects. Toxicity is therefore essentially a qualitative parameter at the screening stage for presumptive POPs. For the twelve POPs presently under consideration for the global negotiations it is generally agreed that there are significant potential risks to man and the environment at present levels in exposed populations.
In other words, toxicity is complex, but in the case of the "dirty dozen", they're all potentially harmful. More on that next.
What are the "dirty dozen"?
The names of the following compounds are linked to the structure of the compound. I am using this link as the source for the very simple description of each compound. For the sake of brevity, I will post descriptions of three of them, and then list the rest, along with a link to very specific information and more structures.
DDT
Perhaps the most infamous of the POPs, DDT was widely used during World War II to protect soldiers and civilians from malaria, typhus, and other diseases spread by insects. After the war, DDT continued to be used to control disease, and it was sprayed on a variety of agricultural crops, especially cotton.DDT continues to be applied against mosquitoes in several countries to control malaria. Its stability, its persistence (as much as 50 percent can remain in the soil 10-15 years after application), and its widespread use have meant that DDT residues can be found everywhere; residual DDT has even been detected in the Arctic.
Perhaps the best known toxic effect of DDT is egg-shell thinning among birds, especially birds of prey. Its impact on bird populations led to bans in many countries during the 1970s.
Polychlorinated dibenzo-p-dioxins and furans ("dioxins" and "furans")
These chemicals are produced unintentionally due to incomplete combustion, as well during the manufacture of pesticides and other chlorinated substances. They are emitted mostly from the burning of hospital waste, municipal waste, and hazardous waste, and also from automobile emissions, peat, coal, and wood. There are 75 different dioxins, of which seven are considered to be of concern. One type of dioxin was found to be present in the soil 10-12 years after the first exposure. Dioxins have been associated with a number of adverse effects in humans, including immune and enzyme disorders and chloracne, and they are classified as possible human carcinogens.
PCBs (polychlorinated biphenyls)
These compounds are used in industry as heat exchange fluids, in electric transformers and capacitors, and as additives in paint, carbonless copy paper, and plastics. Of the 209 different types of PCBs, 13 exhibit a dioxin-like toxicity. Their persistence in the environment corresponds to the degree of chlorination, and half-lives can vary from 10 days to 1 1/2 years. PCBs are toxic to fish, killing them at higher doses and causing spawning failures at lower doses. Research also links PCBs to reproductive failure and suppression of the immune system in various wild animals, such as seals and mink.
Large numbers of people have been exposed to PCBs through food contamination. Consumption of PCB-contaminated rice oil in Japan in 1968 and in Taiwan in 1979 caused pigmentation of nails and mucous membranes and swelling of the eyelids, along with fatigue, nausea, and vomiting. Due to the persistence of PCBs in their mothers' bodies, children born up to seven years after the Taiwan incident showed developmental delays and behavioral problems. Similarly, children of mothers who ate large amounts of contaminated fish from Lake Michigan showed poorer short-term memory function. PCBs also suppress the human immune system and are listed as probable human carcinogens.
The rest of the dirty dozen are: aldrin, chlordane, dieldrin, endrin, hexachlorobenzene, heptachlor, mirex, and toxaphene. You can read more about them here.
So what's the goal of the Stockholm Convention?
You can read a pretty good description of that here. Basically, it isn't just enough to ban certain chemicals; there needs to be a mechanism in place to phase out their use in some countries (e.g. DDT is still used to control the mosquitos and hence malaria in some places), and alternative chemicals need to be investigated, among other factors.
Now what? Is the U.S. going to ratify that treaty or not?
There are high hopes that we will:
The United States is looking to join an international treaty calling for the phase-out of a dozen of the world's most hazardous pesticides and chemicals, a U.S. official said as delegates from 130 nations met here Thursday.
The United States and Russia are the biggest industrialized countries that have yet to ratify the Stockholm Convention on Persistent Organic Pollutants -- a U.N.-sponsored treaty seeking to restrict 12 chemicals commonly known as the "dirty dozen."
Delegates opened high-level talks Thursday in this Atlantic Ocean beach resort on ways to eliminate toxins and narrow loopholes for a few countries still allowed to use some dangerous chemicals.
"Our hope is that next year we will be a party to the treaty," said Claudia McMurray, deputy assistant secretary for environment, speaking on the sidelines of the first U.N. meeting on ways to implement the treaty. "It's a pretty aggressive schedule but that's what we're shooting for."
[snip]
Nonetheless, disagreements in the U.S. Congress over how more toxic chemicals might be added to the ban in the coming years has slowed U.S. ratification, McMurray said.
Indeed, the U.S. has placed pretty severe restrictions on these chemicals (see this link from the EPA). The EPA link is reinforced by the UNEP; go here and download the "Fifth Edition" document (warning, it's huge). Or, just take my word for it.
Regarding environmental issues, the U.S. is far enough behind much of the industrialized world as it is. We have the money and the resources to implement this. We really don't have an excuse not to.