Analysis of Pharmaceuticals, Pesticides and Other Chemicals in Environmental Matrices

Nicole M. Dennis, University of California Riverside; Yu Ye and Wesley S. Hunter, US Food and Drug Administration, Center for Veterinary Medicine

The “Analysis of Pharmaceuticals, Pesticides and Other Chemicals in Environmental Matrices” session at the SETAC North America 43rd Annual Meeting, organized by the SETAC Pharmaceuticals Interest Group, was a highly attended, full-day session that was clearly of interest and necessity to many individuals in the fields of chemistry and toxicology. The inclusion of this session to the program was important because numerous challenges exist in analyzing chemicals that are poorly water-soluble, volatile, rapidly degraded, ionizable, and/or highly adsorptive or hydrophobic, as well as those that form complexes and/or occur in complex mixtures. Those challenges include but are not limited to proper:

• dosing
• sampling
• processing
• identification
• quantification of the analytes

All challenges, if not overcome, can lead to uncertainties in exposure determination and risk assessment.

Sparse availability of comprehensive methods of analysis leads to ambiguous identification and inaccurate quantification of chemicals, which in turn ultimately results in uncertainty in exposure outcomes and overly simplified modeling and risk assessments.

At the session, continuing analytical challenges were identified, and three basic challenges or concerns emerged:

• There are a large number of chemicals detected in the environment that do not have proper analytics or data to determine environmental risk.
• Chemicals are present in the environment in complex mixtures that are nearly impossible to holistically analyze with regards to health risk due to chemical reactions and interactions, and differing inputs across and within environmental matrices.
• There is a need for best practices for analytical methods of chemicals in complex mixtures and matrices.

There were three platform contributions that either examined or were currently examining complex chemical mixtures in the environment:

Coining the phrase “biosolids-agrosoil-biotissue continuum,” Nicole Dennis, University of California, Riverside, presented two instrumental analytical methods for examining a complex mixture of 50 unregulated organic chemicals found in biosolids. She described laboratory and field studies aimed at developing and validating a rapid biomimetic assay that can be used to estimate the bioavailability of this mixture in soil and further predict its accumulation in biological tissues. Field validation data will be collected as the studies continue from passive samplers, earthworms, vegetables and fruits, and results will contribute to a holistic human health and ecological risk assessment.

Anna Robuck, Icahn School of Medicine at Mount Sinai, showed results from her study where concentrations of chemicals in a complex mixture changed in response to water stratification and the season in which the sample was collected. The study demonstrated that the mediated occurrence of chemicals of emerging concern due to seasonal hydrodynamics could affect chemical persistence. Therefore, they concluded that the possibility of effects to marine biota chronically exposed to low levels of a 19-chemical mixture should be considered in future research.

Flannery McLamb, Boz Life Science Research and Teaching Institute, presented the results of a study that examined more than 150 organic chemicals using novel passive-sampling films called the Composite Integrative Passive Sampler (CIPS). This study showed that CIPSs could be used to quantitatively monitor a suite of chemicals, from polar to non-polar, in environmental water bodies. In application, the CIPSs in this study were able to provide chemical concentration data and geographically narrow pollutant origins that were present in the river water.

There were several presenters that assessed environmental exposures or developed analytical methods to assess environmental exposures:

Lantis I. Osemwengie, U.S. Environmental Protection Agency, developed a method to analyze synthetic musk compounds present in fish tissue. This study quantified the concentrations of 11 synthetic musk compounds in fish tissue from across 182 urban river sites and found that two of them consistently bioconcentrate in fish.

Farzana Hossain, Texas Tech University, discussed a method to quantify several constituents in non-fluorinated firefighting foams in order to chemically verify dosing solutions, exposure concentrations, and whole body and tissue burdens in support of ongoing avian chronic toxicity tests conducted to evaluate potential ecotoxicity. This study is expected to provide analytical support to determine average daily intakes and derive toxicity reference values for birds.

A unique approach to studying human environmental exposure to neonicotinoid (NNI) pesticides was presented by Collins Nimako, Hokkaido University. This study showed that tea leaves grown by Japanese organic farming practices contained significantly less NNI residue than traditionally grown tea leaves. Going a step further, this study solicited 103 volunteers and found that adopting a strictly organic diet provided only by Japanese organic farmers reduced NNI residues in urine. The results showed that one might reduce their exposure risk to NNIs by adopting a strictly organic diet.

Carolin Riegraf, Swiss Center for Applied Ecotoxicology, presented on a method to detect anticoagulant rodenticides (ARs) in liver tissue for use in quantifying exposure to non-target organisms such as foxes, birds, hedgehogs and fish. The results from opportunistically sampled animal livers suggested that AR burdens in non-target organisms in the Swiss environment might be a cause to propose risk management.

Voke Tonia Aminone, University of Mississippi, discussed a method to extract fine particulate matter (PM_2.5) from donated filters for use in ongoing zebrafish exposure studies. Preliminary data showed positive correlation between oxidative potential and both PM_2.5 and black carbon concentrations in both months but developmental toxicity in only one. Further study analysis is underway.

There were several contributions that either monitored or developed analytical methods to monitor the occurrence of specific chemical classes detected in the environment:

Michael Gross, U.S. Geological Survey, presented a method to analyze wastewater treatment plant (WWTP) effluent samples for quaternary ammonium compounds (QACs) due to increased use of QACs during the SARS-CoV-2 (COVID-19) pandemic. The study found no correlation between QAC concentrations in WWTP effluents and the heightening of the pandemic.

Carl Fisher, Thermo Fisher Scientific, presented a new method of sample preparation to overcome the challenge of analyzing cationic polar pesticides. This study showed how to fully resolve four quaternary amine compounds using IC-MS/MS for inclusion in regulatory pesticide monitoring programs.

Presenting on spatial and temporal trends of perfluoroalkyl acids (PFAAs), Amila DeSilva, Environment and Climate Change Canada, showed us that PFAA concentrations are declining in arctic seawater, but their persistence and mobility continue to contribute to their ubiquitous Arctic presence.

The final contribution in this group was presented by Alanna Sparagna, Northeastern University, who developed a method for using passive samplers to determine polychlorinated biphenyl (PCB) advective flow rate and the related contaminant transport in column experiments for a better understanding of PCB contaminated sediments. This study found that contaminant fluxes determined using polyethylene (PE) passive samplers were consistent with those determined by extracting overflow water.

One new technology was presented by Amanda McQuay, Agilent Technologies, Inc. This study showed us a new way to analyze 119 chemicals and surrogates from similar classes using hydrogen versus helium as a carrier gas for GC-MS analyses. This technology could potentially save researchers who utilize gas chromatography a considerable amount of time and money.

The session included a 30-minute discussion regarding instrumental and other best practices not typically published but that are nonetheless extremely important for study reproducibility. The wide range of perspectives among the session participants contributed to the kind of fruitful session discussions at the end of the day that we hope to continue to facilitate in future annual meetings.

In addition, this session showcased a total of 22 virtual and in-person poster presentations. All of these session contributions were of high caliber. However, due to word constraints here, it is not possible to completely detail all of the extensive work. Accordingly, the session chairs highly encourage you to view them online before 17 February (meeting registration required), when they are no longer available to view.

Visit the SETAC website to join or learn more about the activities of the SETAC Pharmaceuticals Interest Group.

Authors’ contact information: Nicole Dennis, [email protected]; Yu Ye, [email protected]; and Wesley Hunter, [email protected]

Acknowledgment: Nicole Dennis was supported in part by an NIEHS T32 training grant (T32 ES018827).

Disclaimers: This article reflects the views of the authors and should not be construed to represent USFDA’s views or policies.

Some of the research summarized in this article was conducted in part, under Assistance Agreement No.84024501 awarded by the USEPA to the Water Research Foundation. This article has not been formally reviewed by the USEPA.