Research and analysis

Passive sampling biota replacement feasibility study: summary

Published 9 October 2026

Applies to England

1. Chief Scientist’s Group report summary

This project reviewed scientific literature to understand if passive sampling devices (PSDs) could provide a practical alternative to monitoring chemicals through sampling fish and shellfish. The knowledge gaps identified in this report will inform the design of field studies to test the operational use of PSDs for chemical monitoring.

1.1 Background

The Environment Agency routinely analyses fish and shellfish samples to monitor chemicals that can accumulate in biota. The data are used for trend analysis and to determine the Water Framework Directive chemicals status of waterbodies. Monitoring biota can be challenging and is restricted to a limited number of locations where suitable species are present. PSDs can be used as a surrogate for biota samples and deployed at greater scale, including to locations where biota are not present.   

1.2 Approach

The project carried out a systematic review of the scientific literature where both PSDs and biota had been monitored for chemicals of interest. Reviewed studies had been carried out in rivers, lakes and estuaries, and using a range of biota species and multiple PSD types. Analytical instruments, environmental variables and practical deployment considerations, were also reviewed.

1.3 Results

The literature review indicated PSDs show promise as a reasonable proxy for biota in monitoring certain chemical groups such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and metals. Data on the suitability of PSDs was not available for some chemical groups, e.g. rodenticides. Biological processes such as metabolism and excretion, which PSDs cannot replicate, pose significant challenges. For example, per- and polyfluoroalkyl substances (PFAS) which can undergo transformation following uptake might not be fully represented. PSDs may be less representative for contaminants taken up via dietary or particulate-bound pathways.

The project has recommended three PSD configurations across a range of device types, deployment duration and costs for monitoring chemicals of interest in future field trials.

Using evidence from the scientific literature, a data processing workflow was designed to estimate the concentration of a chemical in an aquatic organism using the concentration measured from a PSD. The workflow centres around ease of use and applicability to most tested chemicals. However, uncertainties with chemical concentration calculations remain, such as assumptions of equilibrium, suitability of partition coefficients from the literature, biological processes (e.g. bioaccumulation, bioconcentration, and biotransformation), and limitations in its application to some compounds. Mitigation strategies are suggested to partially address the limitations.

1.4 Conclusions

PSDs can reliably estimate exposure in many scenarios and have the potential to be used as a first-tier screening tool to identify exceedances of environmental quality standards, triggering targeted biota sampling where needed. While PSDs presently cannot fully replace biota monitoring, they offer a valuable means to reduce reliance on it. The project outputs, such as the PSD recommendations and data processing workflow, will be of interest to the wider scientific community who are exploring the potential of PSDs for chemical monitoring and can support environmental regulators in expanding the knowledge base for biota replacement approaches.  

1.5 Publication details

This summary relates to information from project ENV0007752C - EA002, reported in detail in the following output:

• Title: Passive sampling biota replacement feasibility study
• Science manager: Sam Rose, Chemicals Programme
• Research Contractor: United Kingdom Centre for Ecology & Hydrology (UKCEH)

This project was commissioned by the Environment Agency’s Chemicals Programme and published by the Chief Scientist’s Group which provides scientific knowledge, tools and techniques to enable us to protect and manage the environment as effectively as possible.

Enquiries: research@environment-agency.gov.uk.

© Environment Agency