Separating scientific risk assessment & consumer perception
As scientific concepts become more visible to wider audiences, the distinction between perceived and evidence-based safety has become increasingly important in pharmaceutical development. While simplified narratives continue to circulate, the decisions that underpin drug development rely on laboratory-generated evidence, not isolated hazard signals.
This article examines how toxicology supports robust, evidence-led decision-making across the development lifecycle.
Determination of safety in pharmaceutical development
Consumer-facing ingredient-scanning apps and simplified toxicity scores continue to reach large audiences, presenting outputs in formats that resemble regulatory judgement. These tools use simple scoring systems or colour codes that suggest definitive safety conclusions. However, this contrasts with how safety is determined in pharmaceutical development, where conclusions are built on structured laboratory investigations and reproducible data, rather than simplified classification.
In reality, risk assessment is a structured scientific process that considers multiple factors together: how a substance behaves in a formulation, how it is used, how often exposure occurs, and how the body responds. Two compounds with similar hazard profiles can present very different outcomes depending on these variables.
In drug development, these factors are evaluated through integrated datasets that combine toxicology, pharmacokinetics, and exposure modelling to characterise clinical risk. This approach ensures that safety assessment reflects real-world use and therapeutic context, rather than isolated properties.
In regulated markets such as the UK and EU, safety is assessed based on the complete product and its intended use. This process draws on a weight of evidence, including study design, data quality, and real-world exposure scenarios, to reach a scientifically robust conclusion.
For pharmaceuticals, this evidence directly informs candidate progression, first-in-human studies, and regulatory submissions, making the integrity of laboratory data critical to development success.
Hazard does not equal risk
In toxicology, hazard identification represents an early step in a broader scientific process. A substance may possess hazardous properties under certain conditions, yet, pose minimal or no risk from the route of exposure or at realistic exposure levels.
In pharmaceutical development, this distinction is addressed through controlled laboratory studies that establish dose-response relationships, identify target organ effects, and define safe exposure thresholds. These outputs are integrated with pharmacokinetic data to determine the therapeutic window.
Expert toxicological assessments determine the level of exposure, how often it occurs, the route of exposure, and how the body responds under those conditions, resulting in a contextual assessment of risk.
This is particularly important in drug development, where many compounds exhibit some degree of toxicity. The objective is not to eliminate the hazard entirely, but to understand and manage it within clinically acceptable limits.
Simplified scoring systems can therefore be misleading. A toxicological review may begin with a high-level classification to support early decision-making, but must be followed by a comprehensive evaluation incorporating dose, exposure, and margin of safety.
In practice, this relies on reproducible study design, validated analytical methods, and cross-study comparison to ensure conclusions are robust and translatable to clinical settings.
This principle underpins international regulatory frameworks, such as the EU’s REACH Regulation (EC) No 1907/2006, which requires chemicals to be assessed in relation to their intended uses and exposure scenarios.
In pharmaceuticals, comparable principles are applied through regulatory guidance to ensure that safety data are sufficient to support human exposure.
Reformulation and development implications
Public pressure to remove certain ingredients has increased across sectors. In pharmaceuticals, changes to formulation are driven by optimisation of efficacy, stability, and patient acceptability. In pharmaceuticals, changes to formulation are driven by optimisation of efficacy, stability, and patient acceptability. However, reformulation is not automatically synonymous with improved safety.
Substitutes may have less extensive toxicological datasets or different impurity profiles. Altering a formulation can change absorption, metabolism, or exposure patterns in ways that are not immediately apparent.
From a laboratory perspective, even minor changes can require renewed analytical characterisation, method validation, and stability testing to confirm that safety and quality are maintained. Removing or replacing a component without structured evaluation may introduce new uncertainties, rather than reduce risk.
This highlights the importance of maintaining a consistent evidence base throughout development, where safety is continually reassessed as part of an integrated scientific process.
Toxicology does not end at approval
Post-marketing toxicology has become increasingly important as scientific understanding evolves. For pharmaceuticals, this extends into pharmacovigilance and post-market surveillance, where new data from clinical use, real-world evidence, and ongoing laboratory analysis contribute to continuous safety assessment.
External narratives can evolve quickly, sometimes outpacing formal review cycles. While such pressures may influence development or lifecycle decisions, safety conclusions must remain grounded in validated evidence, rather than reactive interpretation.
Clearly, when simplified outputs are treated as final judgements, rather than starting points for inquiry, they risk amplifying concern where evidence indicates low risk, while weakening trust in regulatory science.
Maintaining scientific rigour is therefore essential, particularly as new data sources and technologies continue to shape how safety information is generated and interpreted.
Integrated evidence, not isolated signals
Ultimately, pharmaceutical safety is not determined by individual hazard signals, but by the integration of diverse datasets generated through laboratory science. Study design, reproducibility, analytical precision, and exposure modelling all contribute to building the evidence required to support regulatory decisions.
As drug development becomes increasingly complex, the role of toxicology continues to evolve – not only in identifying risk, but in enabling informed, evidence-based progression of candidates from discovery through to post-market use.
About the author
Dean Hatt is senior toxicology consultant and toxicology manager at Broughton, a contract research organisation specialising in analytical testing, toxicology, and regulatory consultancy. With more than 30 years' experience in the pharmaceutical and healthcare sectors, Hatt has held a range of toxicology, project leadership, and study management roles across the product development lifecycle, from discovery through to market readiness. His expertise spans off-target toxicology, worker safety, medical devices, novel delivery technologies, and regulatory compliance within GLP and GMP environments.
