A research paper (published in Environmental Science and Technology) has found that one class of chemicals, polyfluoroalkyl substances (PFASs) and one of the so-termed “forever chemicals”, is now ubiquitous in Earth’s rainwater at concentrations above the safe drinking limit. These chemicals have been associated with neurological disorders.
Not only does this pose a risk to humans, these chemicals impact wildlife by entering niche environments and spreading through different species and food chains. This is especially the case with birds, who suffer from macroplastics and microplastics-associated contaminants in the aquatic and terrestrial environments.
Studying the presence of such chemicals not only informs on the relative risks to different animals, it provides a means of tracking the spread of toxic contaminants. Interviewed in The Guardian, scientist Rui Lourenço says that studying the top predators in a food chain is particularly useful as this highlights the way plastic-derived toxins can spread. This is on the basis of ‘biomagnification’ since the concentration of contamination tends to increase as the food chain progress upwards. Here, ‘superpredation’ increases the length of the food chain and the potential bioaccumulation in top predators of harmful chemicals.
Lourenço has been studying bird feathers, especially those of raptors. In the ornithological sense, “raptor” means “to seize or capture” and describes how these birds hunt with their large, strong talons and sharply hooked bills.
As well as races of toxins in feathers, microplastics and chemicals have been found in the gastrointestinal tracts, faeces, and other tissues or organs of several hundred avian species from freshwater, terrestrial, and marine ecosystems. However, it is the study of feathers that most clearly enables the concentration effect to be assessed,
The extent of the problem, as presented by the scientific evidence, is likely to be worse than the collected data suggest. This is because many chemicals are not being extensively tested for their environmental impact; neither are they being routinely monitored. Furthermore, many chemicals lack sufficient information to ascertain their level of toxicity. The European Environment Agency estimates that more than 70,000 mostly low-volume chemicals have little to no toxicity information available.
As well as being detected in greater quantities in predators, studying birds almost provides an indication of the extent of contamination spread around the globe. For example, plastic related toxins are threatening the lives of seabirds even in uninhabited areas.
According to a review published in the journal Aquatic Conservation: Marine and Freshwater Ecosystems, plastic has been detected from far corners of the South Pacific Ocean, including nesting locations of New Zealand albatrosses. The plastic detected has been tested to show it has travelled incredibly long distances in the ocean, affecting birds as they forage and nest in locations where there is typically little to no human contact.
In a different region, Tommy Thompson Park, a human-made peninsula on the shorelines of Lake Ontario, pollutants have been detected in double-crested cormorants. A research study to assess cormorant ground nests for the presence of debris found that all fifty nests sampled were polluted.
Plastic pollutants, whether in the form of microplastics of chemical residues, are presenting an escalating risk both vertically trough the foot chain and horizontally, in terms of every region on the planet. The time for urgent action is now.
