Computational tools reveal ecological effects of pervasive pollutants
March 26, 2025 | Bharti Dharapuram
Using public databases, researchers built networks to link petroleum hydrocarbons (PH) with the biological events they perturb (left) and connected these stressors with aquatic species where they are toxic (centre). Using species sensitivity distributions for each pollutant (right), they prioritized those inducing toxicity across many species even at low concentrations (HC05 - hazard concentration influencing 5% of species in an ecosystem).
Many of the products that we routinely use at home, and in agriculture and industry contain chemicals that are derived from crude petroleum. These are composed of different molecular arrangements of carbon and hydrogen and are called petroleum hydrocarbons. They have become an integral part of our lives, present in everyday cleaning agents, pesticides sprayed on crops and fuels that power our vehicles. However, these ubiquitous chemicals can be toxic to living organisms and can cause a cascade of detrimental and long-term effects when released into the environment.
A recent study used public databases to identify hazardous petroleum hydrocarbons, trace mechanisms of toxicity, identify species-specific effects and quantify thresholds of toxicity. It also performed a risk assessment for aquatic habitats in India with respect to petroleum hydrocarbons. The interdisciplinary study was led by PhD students Ajaya Kumar Sahoo and Shreyes Rajan Madgaonkar along with colleagues in Areejit Samal's research group at The Institute of Mathematical Sciences, Chennai in collaboration with the National Centre for Coastal Research, Chennai.
The research team curated a list of 320 petroleum hydrocarbons, 16 of which with multiple carbon rings have been prioritized as hazardous pollutants. They mapped the adverse effects of 75 of these chemicals on biological pathways using the data collated in multiple public databases. Using network tools, they identified stressors that negatively affect many pathways.
“Crude oil can have thousands of different petroleum hydrocarbons and scaling up can be difficult,” Shreyes says. That is why a framework of connecting stressors to biological mechanisms and eventually ecologically relevant adverse effects is helpful, he adds. Zooming into one such compound called benzo(a)pyrene, the team discovered that it disrupts multiple biological pathways, with detrimental effects spilling over to subsequent generations.
To look at impacts on the ecosystem, they linked petroleum hydrocarbons to vulnerable species and quantified a chemical’s species-specific sensitivity. Their findings showed that crustaceans, fish and molluscs are most vulnerable to the toxic effects of many of the priority pollutants.
Finally, the team derived risk quotients for coastal waters and rivers in India where petroleum hydrocarbons have been measured. They found that four of the eight aquatic sites assessed were at high ecological risk related to at least one of the four priority petroleum hydrocarbons analyzed.
Since the study analyzes data from various sources, missing or incomplete information can influence the results. For example, missing data on taxa-specific adverse effects gives us only a partial understanding of the biological effects of petroleum hydrocarbons. Also, the lack of toxicological experiments across species limits quantitative analysis of species sensitivity. “Though there may be overlap between broad taxonomic groups across geographic locations, one would ideally want to perform risk assessment using the species present at a given site,” Shreyes adds.
This study advances our understanding of the mechanisms by which petroleum hydrocarbons induce toxicity in living organisms. It allows us to monitor environmental quality and perform ecological risk assessments in case of accidental oil spills. “We would like to quantify the mechanisms of toxicity, modeling the concentrations at which chemicals influence biological pathways,” Shreyes says about the group’s plans. They are also interested in dilution effects and seasonal changes that influence the transport of chemicals in aquatic habitats. Other plans include studying the toxicity of a mixture of petroleum hydrocarbons, and the cascading effects of toxin accumulation and transfer along the food chain.
Reference: Sahoo, A. K., Madgaonkar, S. R., Chivukula, N., Karthikeyan, P., Ramesh, K., Marigoudar, S. R., Sharma, K. V., & Samal, A. (2024). Network-based investigation of petroleum hydrocarbons-induced ecotoxicological effects and their risk assessment. Environment International, 194, 109163. https://doi.org/https://doi.org/10.1016/j.envint.2024.109163
