New data for assessing environmental risks associated with chemical weapons dumped in seas and oceans

16 07 2026

In the 20th century, more than one million tonnes of chemical weapons were dumped into seas and oceans worldwide. As corrosion progresses, the submerged munitions gradually lose their integrity, releasing chemical warfare agents that may pose a threat to the aquatic environment. Although this issue was largely overlooked for decades, more attention has been paid in recent years to the assessment of risks posed by these compounds to aquatic ecosystems. A major research gap hindering such risk assessments is the lack of knowledge regarding the toxicity thresholds of chemical warfare agents and their degradation products in aquatic organisms. For many years, researchers from the Department of Hydrobiology, Faculty of Biology, University of Warsaw have been working to provide these crucial data in collaboration with, among others, the Institute of Oceanology of the Polish Academy of Sciences and the Military University of Technology.

In June 2026, two new articles featuring leading contributions from researchers at the Faculty of Biology, University of Warsaw, were published:

1. “Acute toxicity of sulfur mustard and its degradation products to Danio rerio embryos” in Aquatic Toxicology
2. “Chronic effects of the organoarsenicals adamsite and triphenylarsine on the intestinal microbiota of Danio rerio” in Environmental Toxicology and Pharmacology

Both studies provide important data for the assessment of environmental risks associated with chemical weapons historically dumped in the seas and oceans.

The first study focuses on the acute toxicity of sulfur mustard (mustard gas) and its seven major degradation products in fish embryos (Danio rerio). The results show that sulfur mustard is significantly more toxic than model predictions suggested. In addition, both the parent compound and several of its degradation products exhibit strong teratogenic effects, potentially affecting the development and survival of eggs and larvae of fish in areas where chemical weapons were dumped.

The second study examines the role of the gut microbiota as a sensitive ecotoxicological indicator during sublethal exposure to organoarsenical chemical warfare agents in juvenile fish (Danio rerio). The results indicate that the microbiota is both a target and a mediator of toxicity and may serve as a complementary biomarker alongside organism- and molecular-level endpoints, enhancing the environmental risk assessment.

The article published in Aquatic Toxicology was prepared in collaboration by Wojciech Wilczyński, MSc (first author and corresponding author), and Dr Tomasz Brzeziński from the Faculty of Biology, University of Warsaw; Dr Michał Czub (last author) from the Faculty of Biology, University of Warsaw, and the Institute of Oceanology of the Polish Academy of Sciences; as well as researchers from the Military University of Technology. The authors of the article published in Environmental Toxicology and Pharmacology are Wojciech Wilczyński, MSc (first author and corresponding author), and Marcin Musiałowski, MSc, both from the Faculty of Biology, University of Warsaw.

Congratulations! Links to the articles:

1. Aquatic Toxicology:
   https://www.sciencedirect.com/science/article/pii/S0166445X26002080
2. Environmental Toxicology and Pharmacology:
   https://www.sciencedirect.com/science/article/abs/pii/S1382668926001298