Environmental toxicology is the scientific study of the effects and fate of chemicals in the environment. While human toxicology asks “Is this chemical safe for people?”, environmental toxicology asks “What happens when this chemical enters soil, water, air or ecosystems, and what effects does it have on plants, animals and ecological processes?”. Environmental toxicology combines several disciplines including toxicology, ecology, chemistry environmental fate modelling and exposure science.
Environmental toxicology seeks to answer questions like:
• Is the substance toxic to aquatic or terrestrial organisms?
• Does it bioaccumulate in fish or wildlife?
• Does the substance persist in the environment?
• Does it degrade easily or into more toxic products?
• What concentrations might reach rivers, groundwater or soil?
• Could those concentrations result in unacceptable environmental risks?
Every product placed on the market has the potential to interact with the environment. Whether through manufacturing, transport, consumer use or disposal, chemicals and materials can enter air, water, and soil, where they may affect wildlife, ecosystems, and ultimately human health. Environmental toxicology provides the scientific evidence needed to identify, assess, and mitigate these risks. By evaluating these risks, companies can make informed decisions during product development, regulatory submission, and post-market stewardship. The table below highlights how these principles are applied across different sectors.
While the principles of environmental toxicology apply across many sectors, their practical application depends on the product type and the relevant regulatory framework. Nicotine products provide a useful example of how environmental considerations are evaluated in practice.
An environmental assessment is a regulatory evaluation that uses environmental toxicology and exposure data to determine if a nicotine product is likely to have significant environmental impacts throughout its life cycle. i.e. from manufacture and consumer use to disposal. With the growth of electronic nicotine delivery systems (ENDS), particularly disposable devices, regulators are considering not only chemical emissions but also the environmental impacts of batteries, plastics, electronic waste, and product litter. As environmental assessments have become increasingly important for nicotine products, environmental assessment plays a key role in supporting regulatory decision making.
Regulatory authorisation applies the principles of environmental assessment to determine if a product or chemical can be marketed while protecting human health and the environment. Environmental toxicity data generated through laboratory testing, exposure modelling, and risk assessment are compiled into regulatory submissions to demonstrate that potential environmental impacts of a product or chemical have been adequately characterised and managed. Regulatory authorities use this information to assess compliance with applicable legislation, evaluate environmental risks, and determine any risk management measures needed to support product authorisation. Although the scientific principles are broadly consistent worldwide, regulatory requirements and review processes vary across regions, including the United States (US), the United Kingdom (UK), and the European Union (EU) to mention a few.
Environmental assessments differ across jurisdictions primarily because each regulatory authority has its own legislation, guidance documents, and expectations for demonstrating environmental safety. Furthermore, the scope, level of detail, submission requirements, and regulatory review process vary. For example, the US has the most formal environmental review for nicotine products. For US Food and Drug Administration (FDA) Premarket Tobacco Product Applications (PMTAs), applicants generally must comply with the National Environmental Policy Act (NEPA). FDA regulations (21 CFR Part 25) require either:
• an Environmental Assessment (EA), or
• a claim for a categorical exclusion (for products expected not to significantly affect the environment).
The EU/UK do not require a standalone environmental assessment for nicotine products under the Tobacco Products Directive (TPD). Environmental considerations are spread across several frameworks such as REACH for chemicals, CLP for hazard classification, Waste Framework Directive, single-use plastics directive and national producer responsibility schemes to mention a few.
Medicines are one of the sectors where environmental toxicology is most mature and highly regulated. It is mandatory for a marketing authorisation application (MAA) for a medicinal product (which may include nicotine) for human use to include an environmental risk assessment under the European Medicines Agency (EMA) framework. Whilst the UK is regulated by the Medicines and Healthcare products Regulatory Agency (MHRA), the UK MHRA has largely retained the same scientific approach as the EU for pharmaceutical environmental risk assessments. Even after use by a patient, an active pharmaceutical ingredient may be excreted unchanged or as an active metabolite. These substances can enter sewage treatment plants, where they may not be completely removed before being discharged into rivers, lakes, and coastal waters. As a result, biologically active compounds can reach aquatic environments and may affect wildlife, even at very low concentrations. Because of this, environmental exposure is considered an intrinsic part of the benefit-risk evaluation for medicines, and requires a two-part assessment, phase I, the exposure assessment where the predicted environmental concentration (PEC) is determined, and phase II, the hazard and risk assessment, where depending on the PEC, a series of studies may be conducted to assess environmental fate, ecotoxicity and bioaccumulation; the outcomes being included in the Environmental Risk Assessment Report.
Understanding an ingredient’s environmental profile at an early stage including its persistence, mobility, bioaccumulation potential, and ecotoxicity helps identify potential concerns while there is still flexibility to make changes. This allows alternative ingredients or approaches to be considered before substantial time and resources have been invested. For example, if a non-natural peptide is included in a medicinal product, an assessment is required to demonstrate efficient break down during sewage treatment making it unlikely to reach the environment at levels that could cause harm. Early assessment also leads to a smoother regulatory pathway.
Environmental toxicological assessment is not simply about meeting regulatory requirements. It is about understanding environmental consequences before they occur, making better decisions from the onset, and ensuring that innovation and environmental protection advance together. Altogether, the value of environmental toxicological assessment lies in its ability to turn scientific evidence into informed decision. We at Broughton understand the science, the data, and the expert judgement that support those decisions.