A drug can be clinically successful, commercially promising, and still carry an environmental problem nobody planned for.

That usually does not show up in the first investor deck.
It does not get much airtime in early product meetings.
And it definitely does not sound exciting at kickoff.

Until it becomes a filing issue.

Or a data gap.
Or a delay.
Or a question from regulators that sends the team back to generate work they should have scoped earlier.

That is why environmental risk assessment, or ERA, matters in drug development.

Not as a side exercise.
As part of regulatory strategy.

Executive Summary

Environmental risk assessment in drug development evaluates whether a medicinal product could pose a risk to the environment, based on factors such as expected exposure, environmental fate, and ecotoxicity. In the EU, an ERA is mandatory in marketing authorization applications for human medicinal products, and the EMA’s revised guideline came into force in September 2024. In the US, FDA reviews environmental impacts under NEPA and provides pathways for either categorical exclusions or submission of an environmental assessment, depending on the application and circumstances.

What Is Environmental Risk Assessment in Drug Development?

Environmental risk assessment is the process used to evaluate whether the active substance in a drug could harm the environment after patient use, disposal, or release into water and soil systems.

In plain terms, regulators want to know:

• Will this drug end up in the environment?
• How much exposure is likely?
• Does it persist?
• Does it bioaccumulate?
• Could it harm aquatic or terrestrial organisms?

For human medicines in the EU, the ERA is based on the use of the product and the physicochemical, fate, and ecotoxicological properties of the active substance. The EMA guideline is explicit that the ERA is intended to evaluate potential environmental risks and consider risk mitigation measures where appropriate.

Why Environmental Risk Assessment Matters

Many teams treat ERA as a late regulatory document. That is a mistake.

A weak or late ERA strategy can create:

• data gaps close to submission
• extra cost from unplanned studies
• regulatory questions that slow review
• avoidable tension between CMC, nonclinical, and regulatory teams

It also matters because environmental scrutiny is not static. The EMA revised its human medicinal products ERA guideline, and that revised guideline came into force in September 2024, with stakeholder follow-up continuing into 2026. That tells you this is not a dusty compliance topic sitting quietly in a drawer.

When Should ERA Start in Drug Development?

Earlier than most teams think.

Not because every program needs immediate full ecotoxicology work, but because ERA strategy should start early enough to prevent late surprises.

The smart time to raise ERA is when the team is already making decisions about:

• dosage and route of administration
• expected patient population
• formulation and API profile
• global filing strategy
• data generation plans

That is especially important in the EU, where the ERA is a required part of the MAA for human medicinal products. Waiting until submission planning is like discovering you need brakes after buying the car. Technically educational. Commercially irritating.

How ERA Fits Into the Drug Development Process

A practical ERA workflow usually follows the broader logic below.

1. Define expected environmental exposure

Start with the expected use of the product:

• indication
• dose
• treatment duration
• target population
• geographic market assumptions

This helps estimate predicted environmental concentrations and frames whether further assessment is likely needed under the applicable regulatory framework. The EMA guideline uses a stepwise approach built around exposure and effects assessment.

2. Assess environmental fate and behavior

The next question is what happens once the active substance reaches the environment.

Key considerations include:

• degradation
• persistence
• adsorption
• mobility
• bioaccumulation potential

These properties shape whether the substance remains in the environment long enough, or at high enough levels, to matter. The EMA guideline specifically points to fate properties as part of the ERA basis.

3. Evaluate ecotoxicity

If exposure and fate suggest concern, the sponsor may need ecotoxicity data to assess potential effects on organisms such as algae, daphnia, fish, or other species relevant to the assessment framework.

This is where late planning gets expensive. If you discover close to filing that your ERA requires additional studies, your regulatory timeline may suddenly become more “aspirational” than real.

4. Characterize risk and consider mitigation

The final step is not just asking whether a hazard exists, but whether the expected exposure creates meaningful environmental risk.

Where needed, regulators may consider mitigation measures to limit impact. The EMA guideline expressly includes consideration of risk mitigation measures.

EU vs US: The Regulatory Picture Is Not the Same

This is where teams can get tripped up.

In the EU

For human medicinal products, an ERA is mandatory in the marketing authorization application. The EMA’s revised guideline provides the current framework for how to perform the ERA and evaluate risks arising from the use of the medicinal product.

In the US

FDA considers environmental impacts under the National Environmental Policy Act. Depending on the application and the circumstances, a sponsor may submit a claim of categorical exclusion or an environmental assessment. FDA’s guidance on environmental assessment for human drug and biologics applications explains when categorical exclusions apply, when an EA is needed, and what an EA should contain.

That means a company developing a global regulatory strategy cannot assume one jurisdiction’s approach will neatly cover the other.

Why ERA Often Becomes a Late-Stage Problem

Because it tends to fall into the gap between functions.

Nonclinical may think it is regulatory’s problem.
Regulatory may assume nonclinical has it covered.
CMC may not see it as part of core development risk.
Program leadership may not realize it can affect submission readiness.

Then late in development, somebody asks a simple but annoying question:

“Do we actually have an ERA strategy for the EU filing?”

That is when teams discover that environmental planning was not ignored maliciously. It was ignored structurally.

Common ERA Mistakes in Drug Development

Treating ERA as a submission appendix

ERA is not just a document to assemble at the end. It is a data and strategy question.

Assuming US and EU expectations are interchangeable

They are not. FDA’s NEPA-based framework and the EU MAA requirement are related in theme, but not identical in operation.

Starting too late

If studies are needed, late discovery means late cost and late timing pressure.

Ignoring product use assumptions

Exposure estimates depend on real-world use assumptions. Weak assumptions create weak assessments.

Failing to connect ERA to global filing strategy

If the EU is part of the plan, ERA should be part of development planning long before dossier assembly.

What Good ERA Planning Looks Like

A strong approach is not glamorous. It is just disciplined.

Good ERA planning means:

• identifying whether ERA is likely to be material early
• aligning regulatory, nonclinical, and development teams
• understanding jurisdiction-specific expectations
• mapping likely data needs before submission crunch time
• integrating environmental questions into broader risk planning

That is how ERA stops being a late filing problem and starts becoming a manageable part of development strategy.

Takeaways for Founders, Sponsors, and Regulatory Teams

If somebody asks, “What is environmental risk assessment in drug development?”, the clearest answer is this:

Environmental risk assessment is the regulatory evaluation of whether a drug’s active substance could harm the environment after use, based on expected exposure, environmental fate, and ecotoxicity.

If somebody asks, “Why is environmental risk assessment important for pharmaceuticals?”, the answer is:

Because it can affect regulatory submissions, data requirements, development timelines, and market access planning, especially in the EU where ERA is mandatory for human medicinal product applications.

Frequently Asked Questions

What is environmental risk assessment for pharmaceuticals?

Environmental risk assessment for pharmaceuticals evaluates whether a medicinal product, particularly its active substance, could pose a risk to the environment after patient use and environmental release. It typically considers exposure, fate, persistence, bioaccumulation, and ecotoxicity.

Is ERA mandatory for drug approval?

In the EU, an ERA is mandatory in the marketing authorization application for human medicinal products. In the US, FDA evaluates environmental impacts under NEPA, and depending on the case, sponsors may rely on categorical exclusions or may need to submit an environmental assessment.

When should ERA begin in drug development?

ERA strategy should begin early enough to shape development planning, especially for global programs that include the EU. Leaving it too late can create unplanned study needs and submission risk. This timing logic follows from the mandatory role of ERA in EU MAAs and FDA’s defined submission expectations where environmental review is relevant.

What data are used in an ERA?

Typical inputs include expected use and exposure, physicochemical properties, environmental fate data, and ecotoxicology information relevant to the risk assessment framework.

Final Thought

Drug development teams spend a lot of time managing clinical risk, CMC risk, and regulatory risk.

ERA sits at the intersection of all three more often than people admit.

Handled early, it is manageable.
Handled late, it becomes another expensive surprise dressed up as “additional information needed.”

That is not a great ending for any development plan.

References

• EMA: Guideline on Environmental Risk Assessment of Medicinal Products for Human Use (Revision 1, effective September 2024)
• EMA: Environmental Risk Assessment of Medicinal Products for Human Use
• EMA: Questions and Answers on the Guideline on the Environmental Risk Assessment of Medicinal Products for Human Use
• EMA: Industry Stakeholder Webinar on Revised Environmental Risk Assessment Guideline for Medicinal Products for Human Use
• FDA: Environmental Assessment of Human Drug and Biologics Applications
• FDA: Environmental Assessment of Human Drug and Biologics Applications (PDF Guidance)
• FDA: Environmental Assessments and Claims of Categorical Exclusion for NDAs, BLAs, ANDAs, and INDs