27th April 2026

Alarming levels of chemical contaminants found in UK honey


A new study published in the Journal of Agricultural and Food Chemistry reports alarming levels of chemical contaminants in UK honey that may be linked to the use of organic fertilisers such as treated sewage sludge on farmland.

Researchers from the University of Leeds and the Centre for Ecology & Hydrology identified 119 ‘suspect chemicals’ across samples taken from 19 hives located in arable farming landscapes1. Almost two-thirds of all chemicals detected were human pharmaceuticals, including aspirin and flurandrenolide (see Figure 1). On average, each hive contained almost seven different active chemical ingredients, with concentrations of some substances reaching notably high levels (e.g. up to 358 ng/g for aspirin).

 

Nightingale et al (2026) - Contaminants found in honey

Figure 1. Overview of the detection frequency of the suspect organic chemicals in honey. (Nightingale et al., 20261)

Hives surrounded by more intensively farmed land had a greater number of human-origin contaminants present, which strongly suggested that the application of organic fertilisers (such as sewage sludge, manures) could be a key pathway for these chemicals entering the food chain via crops, pollen, and nectar.

Sewage sludge, also known as biosolids, are the by-product of wastewater treatment and are applied to agricultural land as as source of crop nutrients and organic matter. In fact, England, Scotland and Wales are one of Europe’s highest agricultural users of biosolids, with up to 94% of the sewage sludge we produce ending up on agricultural soil2. Despite treatment prior to agricultural use, biosolids contain a cocktail of potentially harmful contaminants including microplastics, pharmaceuticals, PFAS (poly or per fluorinated alkyl substances) and chemical flame retardants. There is currently no requirement to routinely monitor or remove these unregulated pollutants from biosolids. Alarmingly, many of the unregulated persistent contaminants applied to our soils are known to have negative outcomes for human health (e.g. PFOA3) and microplastics have been found to disrupt the reproduction, growth and survival of soil organisms4,5,6.

What does this mean for honeybees and other important pollinators?

For most of the contaminants found in this study, toxicity data for honeybee and other bee and pollinator species does not yet exist, which makes it impossible to fully assess the risks to pollinators, although evidence shows that antibiotics can impact bee health by targeting gut microbiome viability, impairing their immunity7,8.

A similar study in Italy used ‘trace element fingerprinting’ to evidence negative effects on honeybees from regulated toxic metals9 (see Figure 2).  Honeybees were sampled from two different areas: one where sewage sludge had been applied and another where it had not been applied. For honeybees sampled from the area receiving sewage sludge, they noted reduced body size and increased wing fluctuating asymmetry, potentially linked to  lead and mercury derived from sludge.

 

Ferrari et al (2024) - effects of trace elements on honeybees

Figure 2. Effects of trace elements on honeybees (Ferrari et al., 20249)

Honeybees are a cornerstone of the UK’s natural environment, playing a vital role in pollinating both wild plant species and agricultural crops, an ecosystem service estimated to be worth up to £650 million annually to UK food production10, making their health and survival fundamental not only to biodiversity but to national food security.

Tackling the contaminants in sludge

Strengthening sewage sludge regulation is widely recognised as a critical and overdue step. Fidra’s Sewage Free Soils project calls for robust regulatory reform across the UK, including stricter contaminant monitoring, the setting of thresholds for all known harmful substances currently unregulated in sludge, and upstream source control to prevent pollutants such as PFAS and microplastics from entering the wastewater system in the first place. Where source control is not immediately feasible, Extended Producer Responsibility (EPR) schemes, such as those enforced in the EU to tackle micropollutants such as pharmaceutical residues, should be enforced in the UK to ensure that those responsible for introducing harmful substances bear the cost of their removal from wastewater.

The Nightingale et al. (2026) study1 showed that pollinators located in areas with greater arable land cover are at a higher risk of chemical exposure and honeybees are just one species within the broader interrelated ecosystems at risk. Terrestrial and aquatic organisms from invertebrates, plants and microbial communities, through to birds and mammals are all potentially exposed to the complex mixture of pharmaceuticals, microplastics, PFAS and other contaminants that sludge and other waste materials applied to land can introduce into the environment. Until regulations are reformed to reflect the full range of substances of concern known to contaminate sewage sludge, agricultural land will continue to serve as an uncontrolled pathway for harmful chemicals to enter and build up in ecosystems and through food webs. Further research is required to strengthen our understanding of these contaminant pathways.

 

References

  1. Nightingale, J., Woodcock, B. A., Garazade, N., Pywell, R. F., & Carter, L. J. (2026). Presence of Emerging Contaminants in UK Honey─Human Pharmaceuticals a Concern for Honeybees? Journal of Agricultural and Food Chemistry. https://doi.org/10.1021/acs.jafc.5c10414
  2. Defra. 2026. Consultation on the Regulatory Framework for Sludge Applied to Agriculture. https://consult.defra.gov.uk/the-sewage-sludge-team/consultation-on-reform-of-the-regulatory-framework/.
  3. Li, K., Gao, P., Xiang, P., Zhang, X., Cui, X., & Ma, L. Q. (2017). Molecular mechanisms of PFOA-induced toxicity in animals and humans: Implications for health risks. Environment International, 99, 43–54. https://doi.org/10.1016/j.envint.2016.11.014

  4. Lahive, E., Walton, A., Horton, A. A., Spurgeon, D. J., & Svendsen, C. (2019). Microplastic particles reduce reproduction in the terrestrial worm Enchytraeus crypticus in a soil exposure. Environmental Pollution, 255, 113174. https://doi.org/10.1016/j.envpol.2019.113174
  5. Cao, D., Wang, X., Luo, X., Liu, G., & Zheng, H. (2017). Effects of polystyrene microplastics on the fitness of earthworms in an agricultural soil. IOP Conference Series: Earth and Environmental Science, 61, 012148. https://doi.org/10.1088/1755-1315/61/1/012148

  6. Boisseaux, P., Delignette-Muller, M. L., & Galloway, T. (2025). A Quantitative Environmental Risk Assessment for Microplastics in Sewage Sludge Applied to Land. Environmental Science & Technology, 59(49), 26526–26538. https://doi.org/10.1021/acs.est.5c08026

  7. Raymann, K. & Moran, N. A. (2018). The role of the gut microbiome in health and disease of adult honey bee workers. Curr. Opin. Insect Sci, 26, 97−104.

  8. Hariprasath, K., Mohankumar, S., Sudha, M., Saranya, N., Saminathan, V. R. (2025). The Role of Honeybee Gut and Honey Microbiome in Sustainable Bee and Human Health. J. Pure Appl. Microbiol, 19, 19−33.

  9. Ferrari, A., Sturini, M., de Felice, B., Bonasoro, F., Trisoglio, C. F., Parolini, M., Ambrosini, R., Canova, L., Profumo, A., Maraschi, F., Polidori, C., & Costanzo, A. (2024). From molecules to organisms: A multi-level approach shows negative effects of trace elements from sewage sludge used as soil improver on honeybees. Journal of Hazardous Materials, 478, 135497. https://doi.org/10.1016/j.jhazmat.2024.135497
  10. UK Centre for Ecology and Hydrology. Building a buzz about citizen science | UK Centre for Ecology & Hydrology. [online] Available at: https://www.ceh.ac.uk/our-science/case-studies/building-buzz-about-citizen-science.‌