UK Focus v Persistent hormone distortion continues to aff ect fi sh populations


Despite two decades of regulations and infrastructure upgrades, the issue of hormone distortion among fi sh populations in English rivers persists, raising concerns among scientists. While the exposure of wild roach to hormone-altering chemicals has reduced compared to two decades ago, the existing levels still raise alarms.


The phenomenon of endocrine disruption, which triggers male fi sh to develop female proteins and generate eggs in their testes, has been acknowledged since the 1980s. The treated sewage that enters rivers carries a mixture of chemicals linked to the female sex hormone, oestrogen, encompassing naturally occurring substances and those commonly found in everyday items such as plastics, shampoos, and sunscreens. As wild fi sh absorb these chemicals through their gills, they can develop a blend of both male and female biological traits, commonly referred to as being ‘intersex.’


A recent study published in Environmental Science and Technology unveils that despite efforts to enhance sewage treatment facilities and impose stricter regulations, the concern of fi sh hormone disruption persists. Dr. Alice Baynes from Brunel University London emphasises that while the severity of male fi sh displaying female characteristics has diminished in many revisited sites, the impact of endocrine-disrupting chemicals on wild fi sh downstream from wastewater treatment plants in England remains evident.


For the past four decades, researchers have been studying the roach, a resilient and small silvery fi sh prevalent in UK rivers and many parts of Europe. In the 1990s and early 2000s, ecotoxicologists examined over 50 locations along UK rivers, both upstream and downstream from wastewater treatment facilities, for signs of endocrine disruption in fi sh. Some of the most adversely affected fi sh were found in rivers near Leeds, where high levels of alkylphenols—detergents used in textile production—were concentrated. These alkylphenols are closely regulated by the EU’s Water Framework Directive. The study also investigated the factors driving endocrine disruption, including naturally excreted oestrogens from both men and women, as well as pharmaceutical oestrogens used in contraceptives and hormone replacement therapy (HRT).


New European EN 17505 standard for TOC analysis: Elementar’s soli TOC®


Although not mandated by regulations, many wastewater treatment plants have modernised over the past two decades. The Environment Agency commissioned the latest research to determine if endocrine disruption remains a concern. The recent study, conducted by a team from Brunel University London and the University of Exeter, revisited ten of the original river sites. Overall, wastewater treatment facilities now release fewer oestrogens into rivers. However, at 60% of the revisited sites, male roaches displayed intersex traits, with egg cells present in their testes. This irreversible alteration worsens with continuous exposure and negatively impacts breeding. Additionally, 90% of the sites showed male fi sh with elevated concentrations of female egg proteins, a sensitive indicator of estragon exposure, exceeding natural levels.


Various water treatment methods exhibit varying degrees of effi cacy in removing oestrogens from wastewater. Processes like the activated sludge method, involving the infusion of oxygen into sewage tanks, are more effi cient than methods like trickling fi lters, which involve passing sewage over stones. Incorporating tertiary treatments like sand fi lters and reed beds further enhance the removal process. A notable case is the Great Billing facility on the River Nene, which transitioned from trickling fi lters to the activated sludge process around 2001. This change correlated with fewer intersex roaches and reduced levels of female egg proteins in male fi sh. Among the rivers studied, the River Arun exhibited the highest prevalence of sex-reversed fi sh at 10.7%, where fi sh displayed entirely male or female genitalia but had the opposite genetic sex. In contrast, the River Lea and River Nene showed no instances of this phenomenon. Furthermore, the upstream section of the River Arun reported the highest count of intersex male fi sh at 40%. Other studied rivers included the Trent, Lea, Witham, Eye, Avon, Arun, and Bourne.


Dr. Baynes notes an intriguing shift in trends, mentioning that in the past, the extent of the issue was often linked to the size of the sewage treatment facility. However, recent fi ndings indicate that some larger treatment plants, having received more investments and improvements, now exhibit better water quality compared to smaller facilities in towns and villages. This underlines the necessity for smaller sewage treatment plants to enhance their processes signifi cantly to contribute to the health of river ecosystems.


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The new EN 17505 standard was released in November 2023, providing a new European norm for labs using total organic carbon (TOC) analysis. Focusing on soil and waste characterisation, the norm provides guidelines for labs using the temperature-ramping method. It is based on the German norm, DIN 19539.


The new standard is likely to be adopted without alteration in CEN (European Committee for Standardization) member states, which include much of Europe and the UK. It is based on the temperature ramping method, which uses an increasing furnace temperature to separate out the TOC400, ROC, TIC900 peaks.


Accuracy and consistency of TOC analysis results


Elementar, one of the world’s leading manufacturers of high-performance analysis of organic and inorganic elements, contributed data to the development of the standard, along with some of their customers.


Dr Calum Preece, Product Manager at Elementar, said: “The EN17505 standard specifi es requirements to ensure accuracy and consistency of TOC analysis results across different companies, institutions and sectors. We’ve received fantastic feedback from companies using the temperature ramping method, who have shared how it has signifi cantly increased the speed of returning results in their busy labs.”


Standard-compliant TOC analysers are already available


Elementar has also confi rmed that its applicable instruments will be compliant with the new standard, titled ‘Temperature Dependent Differentiation of Total Carbon’, on release. Elementar’s soli TOC®


cube is built for carbon analysis in solid waste, and offers effi cient oxidation,


precise detection and robust calibration routines, ensuring that results align with the standard’s guidelines. As the most sensitive instrument in the market, it offers an unmatched measurement range from 0.001 – 100 % carbon.


For the determination of temperature-dependent carbon fractions, a precise, adjustable temperature is required for reproducible measurements. This is achieved by the dynamic heater in the soli TOC cube, which controls the temperature directly at the crucible.


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