Editor’s Note: Today’s post comes to us from Anna C. Christensen, a regular contributor to the Planned Parenthood Advocates of Arizona blog. I asked Anna to comment on an article from On the Issues regarding the environmental impact of birth control, since Anna has been writing an excellent series of posts for PPAA about sexually transmitted infections. When it comes to science topics, Anna knows her stuff. I hope you’ll find this post as fascinating as I do.
The birth control pill has given millions of people the ability to decide whether and when to have children, and its arrival on the scene in 1960 coincided with increasing concern about population growth – so not only was it seen as a force of liberation for women, it was seen as a tool to stem the tide of the world’s expanding population. Many proponents of zero population growth thought they could end poverty and hunger through the stabilization of the population – as well as conserve the Earth’s finite resources. Lately, however, the birth control pill and other hormonal contraceptives have received negative attention for their apparent ability to introduce endocrine disruptors into the environment.
Endocrine-disrupting chemicals (EDCs) get their name from their ability to interfere with an organism’s endocrine system, which regulates hormones, or a body’s “chemical messengers.” This can wreak hormonal havoc on wildlife, affecting their development, fertility, and immunity. Therefore, EDCs have the potential to decrease or eliminate entire populations of creatures that happened to live in the wrong place at the wrong time.
Hormones work by binding to a complementary receptor. Depending on the hormone and the cell type, a reaction is triggered – perhaps a cell is prompted to synthesize an enzyme, or cell division is stimulated. Sex hormones, such as androgen and estrogen, are responsible for inducing the development of secondary sex characteristics, among other things. There are many mechanisms by which EDCs can disrupt an organism’s endocrine system: They can “trick” a body into recognizing it as a hormone; they can interfere with the function, production, or use of an organism’s natural hormones; or they can interfere with an organism’s hormone receptors.
EDCs started to receive serious attention in the literature in the 1990s. Many chemicals can act as EDCs, including natural estrogen from humans or other animals, as well as synthetic estrogen, including ethinylestradiol, and chemicals with “estrogenic activities,” such as nonylphenol and other alkylphenols, phthalates and other plasticizers, and polychlorinated biphenyls. Other chemicals with the capacity to disrupt endocrine systems of wildlife include organochlorine pesticides and certain pharmaceutical compounds.
EDCs: The case against them
Before we examine contraceptives and their ecological impact, let’s look at the charges that have been brought against EDCs. You might have already heard about the pesticide atrazine and its feminizing effects on male frogs. Natural and synthetic estrogen seem to have similar effects on male fish after entering rivers as part of sewage effluent. Both natural and synthetic estrogen can bind to estrogen receptors of aquatic animals and interfere with their own bodies’ biological processes. The synthetic 17α-ethinylestradiol (a component of oral contraceptives), as well as nonylphenol (a chemical with wide applications that is used in spermicides such as nonoxynol-9), can induce vitellogenesis – the production of a female yolk protein – in male fish, which is the most reported effect of estrogenic chemicals in the waterways. The UK Environment Agency conducted two large-scale studies in which thousands of fish from across the country were examined, and a correlation was found between even low levels of estrogen in the water and male vitellogenesis, which itself was linked to reduced fertility in these populations.
EDCs need not mimic estrogen; for example, metabolites of pesticides such as vinclozin and DDT have been found to have anti-androgenic effects on organisms. By binding to an organism’s androgen receptors, these chemicals can block the actions of testosterone. Tributyl tin, a component of a paint used on the hulls of ships, is a frequently cited EDC; it can masculinize female mollusks and has almost driven some populations to extinction – and it has been banned in many parts of the world.
The chemicals in your birth control
As you can see, the synthetic hormones in our birth control aren’t the only sources for EDCs – chemicals from a wide variety of other compounds can have endocrine-disrupting effects on wildlife. But let’s look specifically at the synthetic estrogen that arises from our contraceptive toolkit. In experiments, estrogen has been shown to be “the most biologically potent” of the EDCs. While the majority of 17β-estradiol and 17α-ethinylestradiol break down very quickly, the trace amounts that don’t degrade tend to persist in the environment. One group of researchers referred to 17α-ethinylestradiol, a synthetic estrogen used in combined contraceptives such as the Pill, the patch, and the ring, as “particularly recalcitrant” – it can accumulate in the soil, waste water, water sentiments, and groundwater.
Let’s look at nonylphenol as well – while its use as a spermicide is dwarfed by its wider use in detergents, emulsifiers, wetting agents, herbicides, and cosmetics, we can still consider the impact it might have as a part of our birth control arsenal. Nonoxynol is used in spermicide and as a lubricant in condoms; it breaks down into nonylphenol, which has also been found to be estrogenic and can end up in waterways.
What about estrogen sources that are first disposed of in landfills? The ring (e.g., NuvaRing) is composed of a polymer called polyethylene vinyl acetate and its active ingredients are etonogestrel and ethinylestradiol. After three weeks of use, an estimated 85 percent of ethinylestradiol remains present in the ring – almost 2.4 mg (down from the original 2.7 mg).
What does this mean for the ecosystem? A Dutch team (in a study specific to the landfill systems, contraceptive usage, and rainfall patterns of the Netherlands) determined that the ethinylestradiol used in NuvaRing has a negligible effect on the environment when disposed of in landfills. It leaches from the ring very slowly, and the sandy soil underneath a landfill can absorb ethinylestradiol, further reducing chances of groundwater contamination. Ethinylestradiol can stay in sandy soil for many years before eventually reaching groundwater; by this time the remainder could have been degraded by microbial or other processes.
Other sources for EDCs
We must look at the deleterious effects of contraceptive-derived EDCs in the greater context. Millions of metric tons of chemical substances are imported to or produced in the United States on a daily basis – in light of this, our use of contraceptives seems to be a drop in the bucket. Other chemicals with estrogenic activity include alkylphenols and bisphenol A (BPA), which have estrogenic potencies far lower than those of natural and synthetic estrogen, yet their prevalence in the environment is at a much higher concentration.
Furthermore, natural estrogen gets into the environment at even greater rates than synthetic estrogen from contraceptives. Women excrete estrogen every day – more or less depending on their cycle. Pregnant women can excrete up to 30 mg of estrogen a day, and this accumulates in the environment as well.
Female humans aren’t the only organisms loosing their estrogen-laden urine into the environment. Agricultural sources of EDCs – fertilizers, pesticides, herbicides, sewage, and other minerals – have the greatest potential for ecological damage. The increasing industrialization and centralization of agriculture is responsible for large amounts of livestock waste entering the water in rural areas. Steroids, such as growth “enhancers” in cattle, are used regularly in agriculture. Pregnant mammals, such as those used for livestock, excrete estrogen, which themselves can affect aquatic and terrestrial species. Agricultural effluent is often disposed of by being spread over fields – untreated! There is so much of it that it cannot be adequately processed by the soils and can either find their way into groundwater or into waterways as runoff.
The majority of EDCs are pesticides – it is estimated that 5 billion tons of pesticides are used every year, and many pesticides have been found to have estrogenic activity. If they don’t bind to the soil they can find themselves in the waterways. According to the USGS, pesticides such as atrazine are found in 57 percent of streams in the United States.
Strategies for treating or reducing EDCs
EDCs are not completely removed during the sewage-treatment process – but they could be. A search through the literature reveals piles of studies by scientists investigating microbes capable of breaking down EDCs into their inert constituents – if these microbes were used in waste water treatment, we would be releasing cleaner waste water into the environment. Residues of EDCs in the waterways depend on a municipality’s waste water treatment systems; unless you know about your local water treatment system’s efficacy, you can’t know how much harm you are doing with the pharmaceutical and personal care products you are washing down the drain.
While microbes in sewage systems are much more effective than soil microbes in degrading free estrogens, wild microbes in the soil can also break down some of these chemicals before they reach the groundwater, adding another line of defense against contamination. Despite the “recalcitrance” of 17α-ethinylestradiol, some microbes exhibit the ability to degrade it quickly; for example, in one study Rhodococcus zopfii (strain Y50158) was able to degrade 17α-ethinylestradiol completely within 24 hours. An enzyme from horseradish also did quite well with natural and synthetic estrogens, degrading most or all of them within an hour, under the right conditions. We already have strategies to effect the breakdown of EDCs – we just have to put these tools to use.
The difficulties involved in testing the effects of chemicals are complicated by the additive or synergistic effects that chemicals might have in combination – normally, when chemicals are tested they are done so in isolation from one another. Additionally, some of these chemicals might be active at concentrations far lower than those at which they are tested. However, as things now stand in the United States, toxicological testing as a whole is woefully inadequate. The burden of proof is on U.S. regulatory agencies to show that a given synthetic chemical is harmful – this means that we may not adequately understand the toxicological effects all industrial, agricultural, and household chemicals might have on the environment and our health. (The EU, by the way, recently introduced robust new regulatory policies that, among other things, shift this burden of proof to chemical manufacturers.)
EDCs can theoretically be kept out of our waterways – we just have to invest in appropriate infrastructure. All kinds of chemicals end up in the water, a testament to inadequate waste water treatment, poor management of runoff, harmful agricultural practices, etc. While estrogen from contraceptives can have negative environmental effects, the vast majority of EDCs originate from pesticides and other agricultural applications. If you ask me, there’s little justification for foisting eco-guilt on those who use spermicides or hormonal birth control – especially since population reduction seems pretty eco-friendly in and of itself. On the other hand, industrial agriculture has a lot more negative ecological consequences than just releasing EDCs into the environment.
Making personal decisions that support sustainable and environmentally responsible agriculture would do more to reduce your ecological footprint than forgoing your birth control pills in favor of a possibly less-effective contraceptive method. (However, depending on your feelings about copper mining, a copper IUD might be worth investigating if your concerns about EDCs originating from contraceptives remain. They are incredibly effective and last for 12 years.) As far as reducing consumption of EDCs goes, giving up hormonal birth control could be a much lower priority than many other lifestyle changes you could make.
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