Hormone distortion still widespread in fish

Wild Roach in English Rivers Exposed to Lower Levels of Hormone-Altering Chemicals, but Concerns Remain

A recent study published in Environmental Science and Technology reveals that wild roach swimming in English rivers are exposed to lower levels of hormone-altering chemicals compared to 20 years ago. However, the current amounts are still concerning, according to scientists.

Endocrine Disruption and Its Impact on Fish

Endocrine disruption, a phenomenon that can cause male fish to produce female proteins and develop eggs in their testes, has been known about since the 1980s. Treated sewage that is pumped into rivers carries a mixture of chemicals related to the female sex hormone, oestrogen. These chemicals can come from natural sources as well as everyday items such as plastics, shampoos, and sunscreens. When wild fish absorb these chemicals through their gills, they can become ‘intersex’ and develop a combination of biological sex characteristics.

The Persistence of Fish Hormone Disruption

Despite upgrades in sewage treatment works and tighter restrictions, the study reveals that fish hormone disruption is still a concern. “Although the severity of male fish showing female characteristics is now reduced at many of the re-visited sites, endocrine-disrupting chemicals are still impacting wild fish living downstream of wastewater treatment works in England,” says Dr. Alice Baynes from Brunel University London.

Focus on Roach and the Study’s Findings

Roach, a hardy and small silvery fish found in most UK rivers near populated areas, has been the subject of study in the UK for the past 40 years. In the 1990s and early 2000s, ecotoxicologists measured endocrine disruption in fish at over 50 UK sites both upstream and downstream of wastewater treatment works. Some of the most affected fish were found in rivers around Leeds, where high concentrations of alkylphenols, detergents used in textile making, were present. The European Union’s Water Framework Directive heavily regulates alkylphenols. The study also analyzed other drivers of endocrine disruption, such as oestrogens excreted naturally by both men and women, as well as pharmaceutical oestrogens used in contraceptives and hormone replacement therapy.

Over the past two decades, many sewage treatment works have modernized, even without regulatory requirements. The Environment Agency commissioned this research to determine if endocrine disruption is still an issue.

The Latest Study and its Findings

In the latest study conducted by a team from Brunel University London and the University of Exeter, 10 of the original river sites were revisited. Overall, wastewater treatment works now discharge less oestrogen into rivers. However, at 60% of the re-visited sites, male roaches were found to be intersex, with egg cells present in their testes. This permanent change worsens with constant exposure and affects breeding. Additionally, 90% of sites showed male roaches with concentrations of female egg proteins, which is a sensitive biomarker for estrogen exposure, above natural levels.

Water Treatment Technologies and their Impact

Different water treatment technologies have varying levels of effectiveness in removing oestrogens from wastewater. The activated sludge process, which involves bubbling oxygen through tanks of sewage, is more efficient than trickling filters, which pass sewage over stones. The addition of third treatments like sand filters and reed beds further improves the removal of oestrogens. For example, the Great Billing works on the River Nene switched from a trickling filter to an activated sludge process in 2001, resulting in fewer intersex roach and lower levels of female egg proteins in male fish. The river Arun had the highest percentage (10.7%) of sex-reversed fish, which have completely male or female genitals but are genetically the opposite sex. On the other hand, the River Lea and River Nene showed no sex-reversed fish. The River Arun upstream had the highest count (40%) of intersex male fish. Other rivers studied include the Trent, Lea, Witham, Eye, Avon, Arun, and Bourne.

The Need for Improvement

Dr. Baynes highlights an interesting observation from the study: “In the past, you’d be able to predict which sites would have higher levels [of endocrine disruption], mainly based on the size of the sewage works. If it was a normal sewage works, you’d expect lots of endocrine disruption downstream. Now it seems that some of those bigger sewage works that have had more investment and have done more are actually cleaner than some of the works in smaller towns and villages. So, some of these smaller sewage works still need a lot of improvement to provide healthy rivers.”

SDGs, Targets, and Indicators

1. SDG 6: Clean Water and Sanitation

   • Target 6.3: By 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials.
   • Indicator 6.3.2: Proportion of bodies of water with good ambient water quality.

2. SDG 14: Life Below Water

   • Target 14.1: By 2025, prevent and significantly reduce marine pollution of all kinds, in particular from land-based activities, including marine debris and nutrient pollution.
   • Indicator 14.1.1: Index of coastal eutrophication and floating plastic debris density.

Analysis

The article discusses the issue of endocrine disruption in wild fish living downstream of wastewater treatment works in England. Based on the content of the article, the following SDGs, targets, and indicators can be identified:

1. SDG 6: Clean Water and Sanitation

The issue of endocrine disruption in fish is connected to SDG 6, which focuses on ensuring clean water and sanitation for all. The presence of hormone-altering chemicals in rivers indicates a pollution problem that affects the quality of water.

• Target 6.3: The reduction of pollution and release of hazardous chemicals and materials is relevant to the issue discussed in the article. The target aims to improve water quality, which includes minimizing the presence of hormone-altering chemicals in water bodies.
• Indicator 6.3.2: The proportion of bodies of water with good ambient water quality is an indicator that can be used to measure progress towards reducing the presence of hormone-altering chemicals in rivers.

2. SDG 14: Life Below Water

The issue of endocrine disruption in fish also relates to SDG 14, which focuses on conserving and sustainably using the oceans, seas, and marine resources.

• Target 14.1: The prevention and reduction of marine pollution from land-based activities, including nutrient pollution, are relevant to the issue discussed in the article. The target aims to protect marine ecosystems from harmful substances that can disrupt the natural balance.
• Indicator 14.1.1: The index of coastal eutrophication and floating plastic debris density is an indicator that can be used to measure progress towards reducing the pollution that affects marine ecosystems, including the presence of hormone-altering chemicals.

Table: SDGs, Targets, and Indicators

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Source: brunel.ac.uk

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