The Toss Away Mistake That Can Harm Birds and Fish

Story at-a-glance -

  • Invertebrates living in sewage sludge from wastewater treatment plants tend to accumulate high levels of pharmaceuticals
  • Starlings that feed on the contaminated invertebrates may also accumulate dangerous levels of the drugs
  • Starlings fed Prozac at levels known to exist in the environment had altered foraging behavior that may affect their ability to survive in the wild

By Dr. Becker

If you’re a pet owner you’re probably aware how important it is to keep medications safely out of the reach of your pets. Human medications can have unintended and sometimes life-threatening consequences in animals, and this is true no matter what the source.

What many people don’t think about, however, is what happens to medications once you take them. Some are only partially metabolized and some are excreted while they’re still in an active state. Once you flush the toilet, these pharmaceuticals end up in wastewater treatment plants, many of which are not designed to remove pharmaceuticals from the water.

Not only does this have implications for human health (pharmaceuticals are showing up in drinking water and sewage sludge used for fertilizer, for instance) but it also poses a risk to wildlife.

Animals receiving perhaps the worst brunt of this pollution are those that feed on the invertebrates (worms, etc.) that live in this contaminated sludge. The invertebrates tend to concentrate higher levels of pharmaceuticals, which are then transferred to the wildlife feeding on them.

Starlings on Prozac

It’s known that birds exposed to pharmaceuticals display some concerning adverse effects. When nestling starlings were fed endocrine-disrupting chemicals, including an ingredient in the contraceptive pill, they grew more slowly and had a dampened immune response.1

A new study by researchers at the University of York, however, investigated what happens when starlings consume pharmaceuticals at levels known to exist in the environment.

First, they measured fluoxetine (Prozac) levels in worms at a wastewater treatment plant. Then they fed worms injected with a similar amount of the antidepressant to starlings for 22 weeks, while a control group was fed drug-free worms.

The two groups showed marked differences in feeding behaviors that could affect their ability to survive in the wild. Dr. Kate Arnold, a Royal Society University Research Fellow in the environment department at the University of York, explained:2

“The normal way that birds forage during winter is when they’re hungry, they have a big breakfast and then during the day they forage to meet their energetic requirements… Then before bedtime, it has a hearty supper and then it can survive a cold dark winter’s night. And that’s what our control birds did, as we expected.

But birds that had been exposed to environmentally-relevant concentrations of fluoxetine, they didn’t do that. They essentially snacked throughout the day and didn’t have a hearty breakfast, so their foraging routine was completely changed.”

Such changes in foraging could impact whether the birds have enough fat reserves to survive periods without food. On the other hand, if they eat too much they may gain too much weight and not be able to escape predators as quickly.

California Shark Found to Contain Extraordinary Levels of DDT, PCBs, and Mercury

It’s not only starlings feeding on worms at wastewater treatment plants that are being affected by environmental pollution. In 2013, fisherman caught a 1,300-pound mako shark off Huntington Beach in California.

The shark was remarkable for a number of reasons. First, it is one of the largest on record. Its age was also estimated to be about 22 years (a typical mako shark lives 25 to 30 years) and it had recently given birth. The shark, which was donated to National Oceanic and Atmospheric Administration scientists, was also incredibly contaminated with environmental toxins.

Animals higher up the food chain, like sharks, tend to accumulate more toxins because their prey also accumulate higher levels of contaminants. Sharks are known to contain high toxin levels, but this particular shark was found to have extremely high levels, including:3

  • Mercury levels 45 times greater than the no-consumption limit for women of child-bearing age and children
  • DDT levels 100 times the legal limit for human consumption
  • PCB levels 250 times the legal limit

Southern California waters are known to be heavily contaminated with PCBs and DDT, but the effects these chemicals are having on sharks is less clear. While no tumors or cancers have been discovered, the sharks are passing the chemicals on to offspring (young great white sharks have some of the highest DDT levels measured).4

Environmental Pollution Threatens Virtually Every Species

Pharmaceutical pollution (and other forms of environmental pollution) is by no means a threat directed at only one species or one country. It’s a worldwide problem, and one that has the potential to threaten virtually every species on the planet.

In 2011, for instance, research was published showing the presence of two types of non-steroidal anti-inflammatory drugs (NSAIDs) – diclofenac and ibuprofen – in otter fur collected from six counties in England. And these studies are only giving a small picture of the chemical load to which otters and other species are exposed in their everyday environment.  As noted by the World Wildlife Fund (WWF):5

When toxic chemicals and metals enter the environment, organisms may absorb them through their skin or ingest them in their food or water. Animals higher in the food chain accumulate these toxins in higher and higher concentrations, a process called biomagnification.

Top predators — including fish, birds, and mammals — can have much higher levels of these toxins in their bodies, making them more likely to experience the diseases, birth defects, genetic mutations, and other deleterious effects of these poisons.”

WWF is advocating for positive pollution control measures at local, national, and international levels, but you can also help on an individual scale, particularly when it comes to pharmaceutical pollution, by not flushing unused medications down your toilet or drain.

The US Environmental Protection Agency (EPA) and other government agencies recommend throwing most drugs in the trash after crushing them or dissolving them in water, mixing them with kitty litter, coffee grounds, or other unappealing materials, and placing the mixture in a sealed plastic bag.

While this really only moves the environmental peril from one place to another – from the sewer to a landfill – it does stop the drugs from travelling through water treatment systems that are ill-equipped to deal with them.