To what extent are these toxins passed along the food chain, and what implications does this have for human health?
Planet Earth, once famously dubbed ‘Planet Ocean', is intrinsically connected to and reliant upon the marine realm. More than 70% of the planet's surface is covered by water and the oceans contain 97% of this.
Globally, the oceans support a plethora of industries and livelihoods. Around a billion people rely on fish as their main source of animal protein, while estimates suggest that marine and coastal ecosystems directly contribute $3 trillion a year in economic goods and services and an additional $20.9 trillion annually in non-market ecosystem services.
But all is not well beneath the waves. Escalating marine pollution, unrelenting overexploitation of fish stocks, destruction of coastal and marine habitats and the impacts of global climate change are all key drivers of oceanic degradation. The economic cost of poor ocean management amounts to at least $200 billion per year and - in the absence of timely mitigation measures - the impact of climate change could inflate this figure by an additional $322 billion per year by 2050.
The plastic age
Industrial plastic manufacturing commenced in the mid-1900s and has since changed the face of the planet. Today, over 280 million tonnes of plastic are produced annually (the manufacture of which accounts for approximately 8% of world oil production). In the UK, over 180,000 people are employed by the plastic industry; processing 4.8 million tonnes of material each year with an estimated £19 billion turnover.
In its purest form, plastic is durable, chemically inert, insulating, malleable, lightweight and affordable - properties that make it extremely valuable. For example, the use of plastic packaging significantly reduces the carbon emissions associated with shipping and transportation and has improved the safety, shelf-life and therefore availability of food and drink to consumers in even the most remote corners of the planet.
The flipside of the ever-escalating production rates is that plastic pollution in the world's oceans is now ubiquitous. The EU estimates that there are 100,000 tonnes of plastic in our oceans, while a recent study on plastic accumulation in the North Atlantic and Caribbean found the highest concentration of plastic debris to exceed 200,000 pieces per square kilometre. In some cases, this concentration is higher than that of plankton - the most basic form of marine life, which underpins the stability of the oceans and atmospheric climate regulation as a whole.
The watery realm, upon which so much life depends, has quite simply become a plastic soup.
Conventionally, the term marine plastic pollution is used to describe macroplastics - large, visible pieces of debris. Haunting images of injured and entangled marine fauna have flooded the media for many years and huge efforts have been made around the world to curb levels of macroplastic pollution.
However, a less-publicised but equally-serious threat has emerged in recent years: that of microplastic pollution - plastic particles measuring less than 5 mm in diameter.
The issue is now being investigated seriously around the world. Mussels, lugworms, several species of commercial fish, seabirds and seals have all been proven to ingest and accumulate plastics (from the nano-scale to the macro-scale [defined as greater than 5 mm]). It is estimated that 95% of northern fulmars (seabirds) contain microplastics in their stomachs - which can cause physical blockages, choking, false-satiation (a false feeling of fullness), and even death from starvation. Several studies have shown some seabirds also regurgitate microplastics to their young whilst feeding.
Plastics adsorb persistent, bioaccumulating and toxic chemicals (PBTs) from the marine environment. Conversely, toxic additives (used during the production and manufacture of plastic) leach out over time into the surrounding environment as a result of UV exposure and physical breakdown. Many of these PBTs are known endocrine disruptors or carcinogens and the key question on the lips of scientists and policy makers alike is: "To what extent are these toxins being passed along the food chain, and what implications does this have for human health and the labelling of organic fish?"
Warning: plastics inside
So where do these tiny plastic particles come from? Well, the breakdown of larger plastic debris is undoubtedly a significant indirect source of microplastic pollution. But of major concern is the number of direct sources - some of which are likely to catch even the most discerning consumer out.
A recent trend amongst cosmetic producers has been the introduction of abrasive, plastic microbeads into a wide range of personal care products such as facial exfoliators, body scrubs and toothpastes.
These microbeads can make up over 10% of a product - which equates to hundreds and thousands of individual beads which are then washed straight down the drain. And, because they are too small to filter out during the wastewater treatment process, they ultimately end up in our oceans.
Introducing the Good Scrub Guide
As part of its wider marine programme, conservation NGO Fauna & Flora International (FFI) is working to address the direct sources of microplastic pollution, starting with the launch of its new Good Scrub Guide (www.goodscrubguide.org).
Featuring the most common facial exfoliators available on the UK market, the guide offers a clear, non-biased tool to help consumers choose products that do not contain plastic microbeads.
At the same time, FFI is drawing on its extensive experience of working with business leaders to encourage the use of biodegradable alternatives to plastic abrasives in personal care products.
FFI has also joined forces with Dutch organisations - Plastic Soup Foundation and North Sea Foundation (Stichting de Noordzee) - to develop and launch a smartphone app called Beat the Microbead that allows consumers to find out whether or not a product contains plastic microbeads by simply scanning its barcode.
Through initiatives like this, we can each minimise our impact on the marine realm. Ultimately the oceans belong to us all, and we have a collective responsibility to ensure that they remain healthy - not only for the sake of humankind but for the vast array of species that live within them.
Tanya Cox is a Project Officer for Fauna & Flora International
Elizabeth Claire Alberts discovers how a sea captain's chance discovery launched a mission to clear up the Great Pacific Garbage Patch ...
Frontline Online: Plastic not-so-fantastic
Why Pakistan’s recent announcement of a ban of non-biodegradable plastics may not be beneficial for the environment. Lorna Howarth reports.....
Frontline Online: Plastic Fantastic?
The Ecologist's Lorna Howarth reports on news and action from the environmental frontline....
Beyond plastic bags: stopping plastic pollution at source
Plastic Pollution Coalition is a new campaign calling for an outright ban on single-use plastic products. Will you support them?