Pollution, including chemical pollution, has been recognised as one of the five direct drivers of the biodiversity crisis by the IPBES (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services). In England, none of the 4,679 inland water bodies assessed by the Environment Agency in 2019 received good chemical status. All have levels of chemical contaminants related to human activities that exceed environmental standards.
What impact is chemical pollution having on biodiversity in the UK?
CHEM Trust partnered with the Marine Conservation Society to investigate evidence of the impacts of chemical pollution on freshwater and marine wildlife in the UK. Our new joint briefing, “State of play of the impact of chemical pollution on freshwater and marine wildlife in the UK” is the result of our investigation, based on exchanges with 15 UK academics throughout 2020. It will feed into the evidence-based recommendations that we will put forward to UK policy makers in the context of a new UK Chemicals Strategy, to better protect marine and freshwater wildlife and ecosystems from the impact of chemical pollution.
The key message from the academics is that chemical pollution is still impacting the marine and freshwater environments, although to different degrees, despite a significant decrease in pollution from certain contaminants such as heavy metals and ammonia since the last century.
Poisons from the past
Based on the data available, the main chemical pollution threat identified comes from legacy persistent organic pollutants (POPs) such as PCBs. Legacy POPs are human made synthetic substances, which didn’t exist before the 20th century, and have been largely phased out globally in the past decades. There is strong evidence of their, sometimes dramatic, impact on marine mammals, and more subtle evidence of their impact on freshwater ecosystems.
In the marine environment, these legacy chemicals, in particular PCBs, have been found to negatively affect the immune system, reproductive system and lipid metabolism of marine mammals in the UK (e.g. killer whales, harbour porpoises, grey seals). This is a source of concern for the long-term impact of chemical pollution on marine mammal populations, with clear evidence that killer whale populations are in decline.
In freshwater, POPs are thought to be responsible for the fact that specific freshwater species, such as certain fish and invertebrates, have only partially recovered from their decline in the 20th century. This is especially the case in areas with greatest urban cover.
An incomplete picture: data gaps on emerging contaminants
In terms of the impact of chemical pollution on aquatic wildlife, the impact from legacy POPs is also by far the most studied in the UK. Academics mentioned that in several instances, it cannot be ruled out that adverse effects ascribed to specific legacy contaminants studied in the field could, in reality, result from a combination effect of a wider range of legacy and emerging pollutants present in the environment.
Unfortunately, the scarcity of data on emerging contaminants makes it difficult to derive their trends and impacts on marine and freshwater wildlife in the UK. Emerging contaminants of concern include PFAS and new generations of flame retardants, neonicotinoid insecticides, and pharmaceuticals.
The chemical landscape has evolved significantly in the past decades, with thousands of new substances put on the market and a strong diversification of compounds. As a result, a much wider range of synthetic substances are present in the aquatic environment, albeit at lower levels. The combined impact of this myriad of synthetic substances (e.g. cocktail or mixture effect) on aquatic wildlife and ecosystems is one of the big unknowns of our time.
By focussing on persistent pollutants from the past, environmental monitoring in the UK paints a very incomplete picture of the true pollution burden of aquatic wildlife and ecosystems. This brings limitations to our understanding of the impact of cumulative exposure to multiple anthropogenic substances.
Mitigating the impact of chemical pollution: academics’ views
The 15 UK academics provided their views on what needs to be done differently in terms of chemical regulation, research, monitoring and funding, in order to mitigate the impact of chemical pollution on freshwater and marine environments:
- The key message regarding chemical regulation is that a more proactive approach is required. This involves preventing new ‘problem’ chemicals from entering widespread use, including avoiding regrettable substitution.
- Several academics were of the opinion that a practical way to address mixture toxicity is to apply a Mixture Assessment Factor (MAF) in the risk assessment of an individual chemical. They also stressed that effect-based mixture toxicity thresholds and Environmental Quality Standards (EQS) are needed to reflect the full pollutant burden of aquatic wildlife.
- Monitoring is recognised as vital in order to identify unforeseen adverse impacts on wildlife and ecosystems. However, longer-term monitoring, integrating chemical, biological and ecological indicators is needed to better assess the real-world and long-term impact of chemical pollution on wildlife and ecosystems.
- Finally, the academics felt funding for both research and monitoring does not reflect the threat posed by chemical pollution.
Lessons for the management of chemicals: CHEM Trust’s views
Lesson one: The urgent need to stop the emissions of very persistent synthetic chemicals
A significant finding from this investigation is the very strong and clear evidence of the impact of legacy POPs on aquatic wildlife, in particular marine mammals in the UK.
The fact that legacy POPs are still present in UK waters and wildlife at levels exceeding current estimated toxicity thresholds is the result of: 1) their high persistence in the environment, 2) the delays in adopting regulatory control measures.
Thousands of other highly persistent chemicals (such as PFAS and other halogenated chemicals) are still being manufactured, used and emitted, and accumulating in the wider environment. There is an urgent need to stop this continued accumulation of further persistent synthetic substances in the environment.
As expressed in our 12 Key Asks for the UK Chemicals Strategy, two urgent actions should be taken to reduce the pollution burden from very persistent synthetic chemicals:
- Emissions of emerging persistent chemicals in the environment should be drastically reduced by phasing out their uses.
- Remaining diffuse emissions of legacy POPs should be reduced to a minimum by identifying and remediating hot spots of contamination.
Lesson two: Anticipate the full burden of exposure in risk assessment
Despite the severe data gaps regarding the trends and impacts from a wide range of chemicals beyond POPs, we know that all new synthetic substances emitted into the aquatic environment are adding to the existing chemical pollution burden. Real-world chemical exposure is a complex mixture of known and unknown natural and anthropogenic substances.
There is an increasing amount of evidence showing that the toxicity of a mixture of chemicals is not equal to the sum of its parts, and most worryingly that mixture toxicity could happen at levels below the toxicity of the individual single chemicals. This suggests that chemical risk assessments based on single substances could underestimate the effect of ‘real-world’ contaminant exposure.
As outlined in our 12 Key Asks, the real-world exposure to a mixture of chemicals, as well as any gaps in scientific knowledge should be accounted for by:
- Developing legislation that addresses combined exposure to chemicals, including implementing a mixture assessment factor (MAF) in risk assessments.
- Applying the precautionary principle in chemical management as absence of evidence does not equate to evidence of absence of harm, and we must therefore be precautionary to all that we don’t know.
Dr Julie Schneider, CHEM Trust Campaigner said:
“We’re in the midst of an ecological crisis. The IPBES report states that “Nature is declining globally at rates unprecedented in human history – and the rate of species extinctions is accelerating”. This is a result of a combination of factors driven by human activity from climate change and habitat loss to chemical pollution.
Global chemical production is projected to increase in the coming decades, but the flow of human made, synthetic substances in the environment must decline urgently if we are to safeguard our natural world. It is time to stop using the natural environment as a laboratory.
The UK Governments should listen to the concerns raised by the academics. Urgent and ambitious action is needed to ensure wildlife, ecosystems, and humans are protected from chemical pollution.”
Dr Francesca Bevan, MCS policy & advocacy manager for chemicals said:
“Chemical pollution is impacting the functioning of marine ecosystems. It took many decades to get legacy persistent chemicals banned during which time they continued to pollute. They continue to cause harm to marine mammals decades after they were banned. As well, today new emerging contaminants continue to enter the environment. We need the UK Governments to urgently put measures in place to stop these extremely persistent chemicals getting into the environment and accumulating, causing untold damage.”
Full briefing: State of play of the impact of chemical pollution on freshwater and marine wildlife in the UK. Bevan, F. & Schneider, J., 2021.
For more information regarding the impact of chemical pollution on wildlife, see our page Wildlife and the Environment.
Read our joint 12 Key Asks for the UK Chemicals Strategy