How water gets contaminated
Cleaners aren't the only culprits—pharmaceuticals & hormones are too. How to lessen their impact
Unlike the aquatic problems cottagers are more familiar with (runoff of septic nutrients, lawn fertilizers, doggy doo), contaminants associated with soaps, shampoos, detergents, and pharmaceuticals involve unimaginably small quantities, typically measured in milligrams per litre, or even nanograms per litre.
Here’s what the terms mean:
• One part per million is the same as one milligram per litre, the equivalent of one minute in almost two years. Surfactant concentrations below even 15 parts per million will kill young rainbow trout.
• One part per billion is the same as one microgram per litre, or one second in almost 32 years. In a University of Victoria tadpole study, as little as 0.03 micrograms of triclosan per litre of water altered thyroid hormone activity.
• One part per trillion is the same as one nanogram per litre. It’s the equivalent of one second in about 31,546 years. When a small lake in northwestern Ontario was dosed with 5–6 nanograms per litre of the potent estrogen used in birth control pills, the fathead minnow population collapsed.
Don’t blame it on your hormones
Hormones are the messengers of your endocrine system, helping to regulate your body’s growth and development. For such major events as fetal development or a teenage growth spurt, hormones -scramble into the bloodstream to urge the process along. In their everyday jobs, they regulate energy levels, reproduction, and responses to stress or injury. Think of the system as a biological jukebox, ordering up the right disc at the right time, placing it in its slot, and spinning it at the correct RPM.
But when endocrine disruptors enter the body and mimic hormones, odd things happen. Some songs don’t play at all, or play too fast or too slow. Triclosan, for example, helps put the thyroids of tadpoles on 45 RPM, instead of 33.
In the most extreme cases, reproductive or sexual characteristics are altered, and male fish start to produce the egg-yolk protein that’s normally associated with mature females.
Since most active ingredients eventually pass through the body and into septic systems and sewage, it’s no surprise that scientists are finding the residues of birth control pills, blood pressure medication, antidepressants, and antihistamines in water—and fish.
To reduce the impact, be especially careful with pharmaceuticals at the cottage. Never flush unused prescriptions or toss them in the garbage (where they’re apt to leach out of the landfill). Instead, check if your pharmacist or municipal hazardous-waste program offers a disposal service.
Why worry about the lake?
Still, the concentrations of pharmaceuticals in lakes are so far below therapeutic doses, writes Susan Holtz, senior policy analyst with the Canadian Institute for Environmental Law and Policy, that “a person would have to drink thousands or even millions of litres of surface water to ingest an amount comparable to that in one pill.” But fish, aquatic insects, and algae are smaller than humans and more intimately exposed to contaminants in water. “The jury is still out on the human health effects,” says Holtz, “but there’s no question there are negative effects on aquatic and marine organisms.”
And what if endocrine disruptors are among a number of stresses, including pesticides and habitat loss, that gang up on fish? They may become, as a US report on salmon in the Columbia River described, “less able to negotiate their world,” or, in other words, less able to escape predators, find food, reproduce, fight off disease, even to school together or sense their way through their habitat. “Real-world fish and organisms aren’t getting hit with one compound at a time. It’s a whole soup of compounds,” says Dana Kolpin, a research hydrologist with the US Geological Survey.
This article was originally published on April 24, 2008