Water pipes gushing - getty 

We are a little island with more than 65 million people living on it, and we have been impacting the environment for thousands of years. As a result, there is no place in the UK that is truly pristine any more. But our scientists, industries and governments are continuously seeking to reduce our environmental impact. In that regard, in my field at least, we are no longer the dirty man of Europe.Professor Sean Comber

Over more than 30 years, Sean Comber has seen countless changes around what the planet’s populations put in our rivers and seas. In fact, many of the more high-profile developments affecting the quality of UK and European waters have been informed directly by his work. However, there is one principle that he believes remains as strong as ever – getting both industry and regulators to base their decisions on sound science.

It is something Sean has advocated throughout a career that has seen him working at a number of public and private sector bodies before he joined the University in 2012. However, his interest in the science of water was first sparked during a childhood growing up in North Devon.

As a young boy living in Braunton, he spent most of his formative years fishing, canoeing and generally playing in the local rivers and estuary. And he freely admits the only thing he was passionate about at school was chemistry. The obvious decision was to combine the two elements, with an undergraduate degree in Marine Chemistry being followed by a PhD examining the levels of arsenic in the Solent and the Tamar estuary.

That, in turn, led to a job with the Water Research Centre (WRc) in the Thames Valley. Initially, his work was focused on the implementation of the Dangerous Substances Directive, looking at the chemicals humans were putting into the environment (principally via sewage treatment works) and the impact they had once they got there.

“It was a fabulous place to work,” Sean says. “The place was full of biologists, chemists, modellers and all other types of scientists and policy influencers. And it was everything I liked doing, lab and field work and detailed analysis. Our core focus was on using sound science to support regulation. The interplay between science and policy is crucial as it has such deep repercussions for social-economics – just look at the COVID-19 pandemic as an example.”

It was during his time in the Thames Valley that, in addition to assessing the impact of existing legislation, Sean’s work began to influence new guidance for trace metals in the aquatic environment. His initial work on dangerous substances looked at chemicals’ total dissolved concentrations but not their bioavailability.

To overcome that, he worked as part of a UK and international team – including regulators, the metal industry and consultants – to develop a model that would mimic complicated laboratory analysis to determine the bioavailable (and hence toxic) portion of a metal simply by measuring the hardness of the water, dissolved organic carbon and acidity. By generating appropriate algorithms, a simple spreadsheet-based model could be derived for use by industry and regulators alike to predict the toxic form of the metal and thus set appropriate standards.

The method was peer-reviewed and published, with the metal industry working with regulators and Sean’s team to ensure the Environment Agency could enshrine it in UK river water quality regulation, something which happened in 2012. The same method is now used to govern permitted copper, nickel, zinc and lead concentrations across Europe.

After 16 years with the Water Research Centre, Sean moved to the global consultancy Atkins where he embarked on perhaps the most key piece of work of his career to date.

Identifying the presence of chemicals in rivers or estuaries is one thing, but it has always been a challenge to assess precisely where such pollution is emanating from. To address that, Sean and his team devised a source apportionment process (a tool called SAGIS) which could (at a 1km grid scale) show precisely where a chemical in the environment was coming from. That made it possible to distinguish whether it originated from point sources from industry and sewage works effluents, or diffuse sources such as agriculture or abandoned mines.

Sean Comber

The project was supported with £130 million of water industry research (The Chemical Investigations Programmes CIP1 to CIP3) to determine the concentrations and sources of priority chemicals entering sewage treatment works, the efficiency of their removal and the concentrations and loads discharged to the aquatic environment. Sean project managed CIP1 while at Atkins and he has been the academic lead for technical and review work on CIP2 and CIP3.

“That work focused predominantly on phosphorus,” Sean says “It is a chemical naturally present in our diet, but also added to our water supply, is in food additives and some detergents as well as huge quantities used in agricultural fertilisers. The SAGIS model has been used to inform huge investment to improve water quality. But there is presently no scientifically rigorous test for phosphorus within the regulations, something we continue to highlight through our research. So what has been enshrined within the regulations is not based on sound science.”

What that means in practice is that billions of pounds are being invested in treating phosphorus at sewage works. However, a fraction of that amount is invested in preventing it resulting from agricultural run-off, despite the fact they are equal parts of the problem.

The reason for this, in Sean’s thinking, is obvious – with the water industry, you can implement change at a sewage works and the impact is instant. Implementing measures on farms is a much slower and less certain process. However, he does believe that Brexit and UK government initiatives, such as the Environmental Land Management Scheme (ELMS), could offer the potential for a renewed focus on that legislation, and the potential for subsidised action that farmers can take themselves to upgrade infrastructure and reduce loss of contaminants into the aquatic environment.

In addition to metals and phosphorus, an increasing amount of Sean’s time is now spent examining the impact on our waterways of pharmaceuticals. The human population’s quest to find solutions to our many and varied, local and global health crises is resulting in ever more complex compounds being produced and prescribed. But there is still work to be done to be more holistic in linking prescription to environmental impacts and regulation.

“Sewage works are predominantly designed to deal with paper, urine and faeces,” Sean says. “The removal of chemicals such as pharmaceuticals, and metals for that matter, is happening by chance unless specific treatment is used. Even though many pharmaceuticals are biodegraded to a high degree during treatment, a small concentration – very small in some cases, parts per trillion – will pass into or waterways owing to the volumes we use in our everyday lives. The problem comes when uncertainty around their fate and effects drives high safety factors, leading to proposed river water standards many times lower than the concentrations being discharged, which would require treatment. We have yet to enshrine standards for pharmaceuticals into regulation, but if and when we do, there will potentially be huge costs involved. So it is – once again – essential that the science is right.”

A simple solution, to an outsider at least, would be to identify a way to treat certain chemicals at sewage works to prevent them passing into rivers. However, a few years ago Sean looked at how much it would cost to remove the contraceptive pill alone – the cost was £26billion across the UK, just for that one chemical. In a post-COVID climate where both public and private sectors are looking at saving rather than spending, such a bill could raise eyebrows.

However, Sean does believe the pandemic may also offer a potential means of addressing the issue. During 2020, he and colleagues from the University and Royal Cornwall Hospital Trust published research in the Journal of Antimicrobial Chemotherapy suggesting the use of antibiotics in people with COVID-19 could result in increased resistance to the drugs’ benefits among the wider population. However, they also highlighted that alternative treatments – acknowledged to have less environmental impacts – were available.

Speaking at the time, he said: “By understanding the effects of such treatments, we can potentially inform future decisions on prescribing during pandemics, but also on the location of emergency hospitals and wider drug and waste management.”

A separate piece of work, published early in 2021, showed the increased global use of antiviral and antiretroviral medication – used to treat HIV/AIDS, influenza and COVID-19 in some countries – could have a detrimental impact on crops and potentially heighten resistance to their effects.

Sean says that, as an applied scientist, he fully appreciates that pharmaceutical companies are under huge pressure to develop new drugs at almost breakneck speed. The work on COVID-19 vaccines is a prime example. However, he believes there are always opportunities to continue to develop and improve upon the environmental assessments used in the drug development process.

He also advocates a cradle-to-grave approach from prescription to ultimate fate in the environment and, most importantly, the development of science-based water quality standards that take account of the full fate and impacts of pharmaceuticals (and other organic chemicals) on the receiving water environment. By investing in better understanding the environmental impacts of these chemicals, he says, we could prevent multi-million or billion pound clean-up campaigns down the line at sewage works.

Sean Comber

In some senses at least, Sean has come a long way since those days stood by the sea in North Devon. But his enthusiasm for his subject is as strong as ever. That can be evidenced through the fact that – as well as his own ongoing work – he is passionate about nurturing the next generation of environmental scientists, with several of his former students already working for agencies at the forefront of national and international research and legislation.

“I want all my students to realise that chemicals do have an impact, but that there are a range of factors affecting that,” Sean says. “Put simply, they need to see all sides of the story. That’s why I get all my students out into the field and talking to industry, and I encourage them to think about producing work of a quality that could be peer-reviewed and published. At the end of the day, I am doing my bit now, but it is today’s young people who have the real power to change the world.”


Biogeochemistry Research Centre

Researching the environmental behaviour, fate and impact of nutrients, metals and pharmaceuticals in terrestrial, atmospheric and aquatic systems.
The Biogeochemistry Research Centre comprises expert researchers and instrumentation, with acknowledged international leaders in organic geochemistry and environmental analytical chemistry and a strong focus on marine science and current and past ecosystems and climates.
Scientists working with a University of Plymouth team on sea ice in the Arctic (credit: Simon Belt/University of Plymouth)
Marine Institute

Marine Institute 

The University’s Marine Institute is the first and largest such institute in the UK. 
We provide the external portal to our extensive pool of world-leading experts and state-of-the-art facilities, enabling us to understand the relationship between the way we live, the seas that surround us and the development of sustainable policy solutions. 
We are integrating our multidisciplinary expertise in marine and maritime research, education and innovation to train new scientists, engineers, policy-makers, artists, technicians and business managers of the future. 
Sustainable Earth Institute hero

Sustainable Earth Institute 

The Sustainable Earth Institute is about promoting a new way of thinking about the future of our world. 
We bring researchers together with businesses, community groups and individuals to develop cutting-edge research and innovative approaches that build resilience to global challenges. 
We link diverse research areas across the University including science, engineering, arts, humanities, health and business.