Non-Target Screening Is Shaping Environmental Monitoring Strategies
Dr. Emmelianna Kumar discusses how non-target screening workflows permit a more holistic view of environmental quality.
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“With the multitude of chemicals in our environment ever increasing, selecting emerging chemicals to focus monitoring, research and regulatory efforts on requires prioritization of those expected to pose the greatest risk,” Dr. Emmelianna Kumar, specialist policy advisor at the Environment Agency, told Technology Networks at the 2024 International Symposium on Chromatography.
But how do we prioritize the chemicals with which to concentrate our efforts? Kumar suggests approaches should capitalize on targeted analytical methods and non-target and suspect screening (NT/SS).
Targeted methods involve the analysis of target chemical compounds using quantitative and trace analytical methods. “Targeted analytical methods support chemical risk assessments by providing exposure information, which is subsequently integrated with hazard and dose-response information,” explained Kumar. “However, it is impractical to optimize targeted methods for quantifying all possible chemicals.”
Advances in sample preparation, high-resolution mass spectrometry, data processing and chemometrics, have led to the development of NT/SS methods as holistic approaches for characterizing contaminants.
“A major advantage of these approaches is that previously unexpected or unknown compounds may be detected,” said Kumar. “Importantly, and in contrast to targeted analysis, this approach also facilitates the mining of the data retrospectively to search for chemicals that were not included at the outset, without the need to re-analyze the samples.”
The data generated from NT/SS can contribute to prioritization strategies and can lead to the development of targeted methods for new chemicals, highlighting the complementary nature of these approaches for effectively managing chemical risks in the environment.
In this article, Kumar provides examples of projects that have utilized NT/SS to help monitor environmental contaminants and explains how data from these projects are being used to assign priority to emerging environmental contaminants.
Environmental monitoring projects embracing NT/SS
“Monitoring data is vital in response to existing and emerging chemical risks,” stated Kumar. “The results of all the environmental chemical monitoring programs at the Environment Agency, including those that utilize NT/SS approaches, are used to inform decisions and provide solutions to support chemical and pesticide policy development.”
Otters as an indicator of environmental exposure
One such project underway is the H4 Otter Project. This project comes under the H4 Indicator “Exposure and adverse effects of chemicals on wildlife in the environment”, which forms part of the UK Government’s 25-Year Environment Plan. Published in 2018, the plan sets out goals for improving the environment, including reducing the harmful impacts of pollution on human health and the environment.
One of the freshwater indicators used to measure whether we are moving towards the goal of managing environmental exposure is the otter. When asked why otters were chosen as an indicator, Kumar explained: “Otters are semi-aquatic, apex predators and therefore present an ideal opportunity for investigating potential exposure, bioaccumulation and biomagnification of chemicals. Like all free-living organisms, otters are exposed to highly dynamic, complex mixtures of chemicals.”
Using tissues from dead otters found in England, the Environment Agency has been monitoring a suite of chemicals for the last few years. “These include metals, polychlorinated biphenyls, polybrominated diphenyl ethers and, more recently, per- and polyfluoroalkyl substances (PFAS),” said Kumar.
Non-targeted screening has been applied to a subset of otters to find out if other chemicals are present in these samples.
Environmental monitoring influences new policies on pet parasite treatments
Kumar explained how environmental monitoring has revealed the widespread occurrence of fipronil and imidacloprid in rivers throughout England, frequently at concentrations expected to exert effects on biological organisms.
These chemicals are banned for agricultural use due to adverse environmental effects but are still widely used as parasiticides in companion animals, such as cats and dogs. They are highly toxic and associated with declines in the abundance of aquatic invertebrate communities.
“As it is important to maintain the health of pets and humans whilst minimizing harm to wildlife and the environment, a One Health approach is needed, and this involves engagement with many different stakeholders,” Kumar said.
Kumar works closely with pharmaceutical companies, regulators and veterinarians among others to develop methods to mitigate the environmental impact of these chemicals.
“I used the Environment Agency’s monitoring data to persuade the Royal Veterinary College, University of London, to incorporate lectures on the environmental impacts of veterinary medicines in their MSc courses, and subsequently deliver an annual lecture to inform the next generation of veterinarians and biologists of this important issue,” Kumar said.
NT/SS plays an important role in monitoring fipronil and imidacloprid levels in the environment and is used to evaluate the success of these interventions. “Some pet owners are choosing oral parasiticides for their pets in favor of topical spot-on treatments, partly because their environmental impact is assumed to be lower,” said Kumar.
“However, these products contain different chemicals, such as isoxazolines, and less is known about the potential environmental impacts of these chemicals. Monitoring various matrices using suspect screening provides a relatively quick and cost-effective method for identifying where these chemicals end up.”
Pre-empting emerging pollutants in wastewater
Other projects embracing NT/SS include the Chemicals Investigation Programme (CIP) – A collaborative effort between key stakeholders, including regulators (the Environment Agency, Defra and Natural Resources Wales), the UK Water Industry Research (UKWIR) and ten large water and sewerage companies in England and Wales.
The CIP is investigating how chemicals enter the sewage system and how effective current wastewater treatment processes are in removing them. Kumar explained: “CIP provides essential data on effluent quality, helping to track changes in chemical concentrations over time, enabling the evaluation of the effectiveness of regulatory interventions and changes to wastewater treatment processes.”
The fourth round of the project, which is currently in the planning stages, includes details for a suspect screening investigation. The hope is that this could provide insights into which chemicals, in addition to those historically monitored, are present in wastewater treatment samples throughout the UK.
“This enhances the capacity of CIP to not only monitor known chemicals but also to anticipate and respond to emerging contaminants,” suggested Kumar. “This will contribute to a more dynamic and proactive approach to managing chemical pollution in the water environment.”
NT/SS data helps prioritize emerging contaminants
The Environment Agency has established the Prioritisation and Early Warning System (PEWS) to ensure appropriate regulatory focus on substances of emerging concern.
“The Environment Agency is working towards integrating data generated through novel analytical techniques like NT/SS into the PEWS process. For example, chemicals identified via the H4 Otter Project or the CIP suspect screening project may be nominated to enter the PEWS process, so that the Agency can focus PEWS resources on chemicals that are most likely to occur in the UK environment,” explained Kumar.
Once chemicals have been nominated, PEWS screen them based on their occurrence in the UK and their known hazard and exposure information to assign them a priority level.
Chemicals are assigned the highest priority level (1) if it is certain they are present in the UK environment, and it is certain they are hazardous and hence pose a high risk to health or the environment. “These chemicals are given the highest level of attention, and the Environment Agency may consider targeted interventions or the development of regulatory strategies via the Chemical REgulatory Strategies Tool (CREST), to mitigate their impact,” added Kumar.
“In some cases, this may lead to the development or optimization of targeted analytical methods to quantify those chemicals in particular matrices. Particular chemicals may also be added to the Environment Agency’s bespoke library databases, to enable subsequent samples that are analyzed using non-targeted approaches to be screened for these high-priority compounds.”
Data collected from the NT/SS projects described above not only feed into the PEWS process but are also vital in supporting broader efforts to identify, prioritize and regulate emerging pollutants.
Kumar now chairs a cross-government working group for NT/SS. The aim of the group is to coordinate these approaches and reduce duplicate efforts across different organizations.
Kumar concluded: “The group provides a forum for exchanging knowledge, developing best practices and setting priorities for chemicals on a national scale. The group has members from ten organizations across the UK that are working together to progress the use of NT/SS approaches to support the monitoring and regulation of emerging chemicals in the environment.”
