By Cate Twining-Ward, Colin Chapman
- Humanity’s heavy daily reliance on pharmaceuticals has unsettling effects on water quality and wildlife.
- Studies highlighting the impacts of pharmaceuticals on wildlife have been focused on aquatic organisms, especially fish. Given the current lack of data, additional research this area is clearly warranted.
- Advanced treatment methods can reduce the concentration of harmful pharmaceutical compounds in wastewater up to 95%. So the question is, are we willing to adapt treatment so that a safe and equitable future for both people and wildlife is possible, a new op-ed asks.
- This post is a commentary. The views expressed are those of the authors, not necessarily of Mongabay.
When we routinely flush a toilet, the waste is hurled away so quickly that most of us don’t give it a second thought. But that waste, despite our inclination to dismiss its existence, does not in fact, vanish. The disappearance of our waste down the toilet is merely a comforting illusion. In North America, urban wastewater, and the contaminated and polluted water created by human use, require expensive and energy-intensive resources to treat properly. This is an expense that is difficult for developing countries to meet. We are left to wonder: what exactly is in our waste, and where is it going?
It is likely not the first thing to come to mind, but our heavy reliance on pharmaceuticals day in and day out has unsettling effects long after we take these drugs. Pharmaceuticals are entering our environment both at sites of production and once they have been excreted. Annually, thousands of tons of biologically active compounds are excreted, and our drug-riddled feces and urine are dumped into the environment as pharmaceuticals are not degraded or removed in most sewage treatment plants. In the US, 60% of this sludge is used as fertilizer for cropland. This means that our ingested pharmaceuticals—there are over 4,000 types used globally—are being spread onto crops. Furthermore, in many places around the world, wastewater cannot be treated. Globally, 20 million hectares of farmland are fertilized with non-treated wastewater, an area slightly smaller than the size of the United Kingdom.
In most developing countries, wastewater treatment plants lack functionality and large-scale coverage. Without effective wastewater treatment systems, countries face the threat of large-scale water pollution and farmers are forced to use poor-quality water for crop irrigation—both of which pose serious risks to public health.
The agricultural impact of human sewage is small relative to the enormous quantity of livestock manure also used as fertilizer. This manure also contains pharmaceuticals. In fact, 73% of all antimicrobial drugs sold today are fed to livestock.
The use of pharmaceuticals in meat production is of particular concern for tropical mammals in developing nations. Estimates suggest that more than 105,000 tons of antimicrobial drugs will be administered to animals consumed for food by 2030. It is also expected that tropical countries like Brazil, India, China, and South Africa will nearly double their use of antimicrobials by that year. In general, meat production plateaued in high-income countries in 2000 but it has grown by 68%, 64%, and 40% in Asia, Africa, and South America, respectively. Meat production in Africa is expected to rise dramatically in the coming decade as many African countries are selling large amounts of land to meat producing businesses from countries that are capital-rich but lack suitable land for agriculture.
For example, >50 million ha of farmland in Africa, roughly the area of France, was appropriated by oil- or capital-rich (but food-poor) Middle Eastern or Asian countries in 2009, with the products destined for export. In many cases, the area of appropriated land used comprises a large proportion of the available agricultural land— in Uganda ~ 14%, in Mozambique ~ 21%, and in the DRC ~ 48%. This trend is partially driven by the increasing wealth of countries like China and India, and an associated increased preference for animal-based diets.
The effect of pharmaceuticals on terrestrial wildlife has thus far received almost no attention. In the past, studies highlighting the impacts that pharmaceuticals have been focused on aquatic organisms, especially on fish and their behavior. Given the current lack of scientific data, additional research this area is clearly warranted.
It is not a new finding that tropical mammals are being exposed to pharmaceuticals. For over 15 years there has been concrete evidence that non-human primates and humans share genetically similar gut bacteria that had been exposed to antibiotics. Scientists have found that the chimpanzees, and gorillas that live in the same national parks share antibiotic resistant genes in their bacteria with people—genes that are resistant to the antibiotics taken by people.
See related: The thick of it: Delving into the neglected global impacts of human waste
One of the clearest cases of pharmaceuticals causing devastating population-level effects occurred on the Indian subcontinent, when vultures were poisoned by livestock carcasses. The livestock had been medicated with diclofenac, a non-steroidal anti-inflammatory drug. This resulted in the death of over 95% of Gyps vultures (Gyps bengalensis), one of the most common raptors of the Indian subcontinent. Prior to the veterinary use of this drug, populations of Gyps vultures were so large they were considered a risk to aircraft—populations were in the tens of millions. Despite this horrific incident, diclofenac is presently the 12th best-selling generic drug globally. More than 1,223 tons of it are consumed annually by people.
Another factor we must consider is that the manufacture of pharmaceuticals is now shifting to tropical countries, particularly India and Brazil. The consequences of the development of the pharmaceutical industry in tropical countries and the associated increase use of these chemicals is unknown.
Given the increased presence of pharmaceuticals in the environments of tropical countries, the close association of people and wildlife in the tropics, and the fact that pharmaceutical drugs are often designed to alter reproduction and behavior, research into pharmaceuticals in the tropics is urgently required.
Particularly, the consequences of wildlife being exposed to pharmaceuticals at all stages of life, including as infants, needs to be known. Since these animals are in the early stages of development, they are most vulnerable, as they do not have the metabolic capacity to deal with foreign chemicals. Exposure to chemicals in human birth control pills or anti-depressants will undoubtedly affect the development of infant wildlife, and we must understand these effects sooner rather than later if we are to construct informed conservation plans for endangered species. With more scientific data, conservation biologists will be better able to proactively prevent population declines, as opposed to having to rebuild populations once negative situations have already unfolded.
Almost 60 years ago, Rachel Carson published Silent Spring and made North American society aware of the dangers of the adverse environmental effects caused by the indiscriminate use of pesticides like DDT. Her book was a call to action—action that is needed now just as much as it was in her time.
Today, our use of pharmaceuticals, and the rate at which they enter our environment, is endangering ourselves just as much as it threatens wild populations of animals. The evidence is clear.
The question isn’t whether we need to give up pharmaceuticals. Recent studies have shown that advanced treatment methods can reduce the concentration of harmful pharmaceutical compounds by up to 95%. Rather, the question is whether we are willing to adapt the management and development of wastewater treatment facilities across the globe, so that a safe and equitable future for both people and wildlife is plausible.