Environmental Science: Processes & Impacts blog

Greg LeFevre is an assistant professor of environmental engineering and science in the Department of Civil & Environmental Engineering and IIHR—Hydroscience & Engineering at the University of Iowa where he started in 2016. He did his BS at Michigan Tech, MS and PhD at University of Minnesota, and Postdoc at Stanford University all in environmental engineering. The LeFevreLab focuses on elucidating biotransformation products and pathways of emerging organic contaminants with the goal of informing improved design of ‘engineered-natural’ treatment systems for non-point pollutants, like urban stormwater and agricultural drainage, and transform wastes into resources, protecting people and ecosystems. Greg has received multiple sources of recognition for his work, including the National Science Foundation CAREER Award, the University of Iowa Early Career Scholar of the Year award, the American Chemical Society Editor’s Choice award and ACS Best Paper award, the Royal Society of Chemistry Environmental Sciences ‘Best Paper’ and multiple ‘HOT’ articles, National Academy of Engineering Frontiers of Engineering fellow, the AEESP Best Dissertation, amongst others.

Read Gregory LeFevre’s Emerging Investigator Series article “municipal wastewater as a year-round point source of neonicotinoid insecticides that persist in an effluent-dominated stream” and read more about him in the interview below:

Your recent Emerging Investigator Series paper focuses on Municipal Wastewater as a Year-Round Point Source of Neonicotinoid Insecticides that Persist in an Effluent-Dominated Stream. How has your research evolved from your first article to this most recent article? 

In some ways, my work has changed greatly through time, and in others it is very consistent. I did my PhD at the University of Minnesota focused on the fate and biotransformation of organic contaminants from stormwater in bioretention cells, and my postdoc was at Stanford focused on emerging contaminants in stormwater as well as plant metabolism of emerging contaminants during water recycling. Since starting at University of Iowa as a faculty member, we’ve been continuing in these areas and are also very interested in the fate and transformation of so-called ‘target-specific’ pesticides like the neonicotinoids. These compounds are so interesting and important because, although the parent compounds are explicitly designed to be less toxic to many non-target organisms, only very slight alterations to the chemical structure can dramatically alter the toxicity, reactivity, and fate of the transformation products.

What aspect of your work are you most excited about at the moment?

I am really interested in how complex chemical exposure mixtures occur and change in the environment and could lead to unanticipated effects to biota. Complex mixtures are important because of the potential for interactive effects on organisms (e.g., drug-drug interactions); when mixtures change in space and time, so can the risk profile. New collaborative work that we’ve been doing at the field study site featured in this paper has been probing some of the spatiotemporal drivers of complex mixture evolution, as well risk patterns. Mixtures are how chemicals occur in the real environment.

In your opinion, what are the most important questions to be asked/answered in this field of research?

I believe that we are standing at the verge of multiple big-data “omics” revolutions, with a huge opportunity to converge high res mass spec with biological applications (transcriptomics, genomics) to link chemical exposures with effects to biota—which is ultimately why we care. This will be critical to being able to evaluate complex chemical mixture effects on organisms, which is very much a grant challenge—and difficult.

What do you find most challenging about your research?

I think that there is always a push-pull struggle between working at the interface between the fundamental but realistic and the more applied but less controlled. Navigating that is always a challenge, and I think that it’s important to be able to—and for journals to value—work across that spectrum. Field studies can be more ‘messy’, but are so important!

In which upcoming conferences or events may our readers meet you?

I usually am at ACS once a year, often at SETAC, AEESP, EmCon, and Gordon Env Sci Water. Of course, during the pandemic, that has been really disrupted.

How do you spend your spare time?

I have two little kids (4 and 2 years old), so not much spare time, but I like to do outdoors activities as much as possible. Fortunately, my girls love fishing (at least when we are catching fish), catching bugs, and exploring in the woods. A new creek is an all-day itinerary.

Which profession would you choose if you were not a scientist?

I honestly never really considered doing something that was not “a scientist” at least of some sort. My dad’s influence was really big on me; he was a woodworker by trade and taught me angles, planning, and precession—but his passion (and now retirement occupation) has always been ecological restoration. He took me with him to weekly volunteer workdays since I was four, and all of my jobs, internships, and education have been around the environmental sciences.

Can you share one piece of career-related advice or wisdom with other early career scientists?

This might be both the worse and best advice to early career researchers during the pandemic: Make friends before you need them. By that, I mean reach out to folks across your university who might be of potential connection or collaboration before you ask them for something or want them to join on a collaboration or proposal. The first year I was at UIowa, I met with someone new every or every other week, from Public Health to Chemistry to Education to Water Resources, etc. and mostly listened, but also got to share a little of what I do and my interests. Totally pull the ‘new person’ card, people will give you an hour. It totally makes coming back to people later with an idea less awkward, and some have resulted in great collaborations—and it’s much better than people only coming together to rally around a proposal (assuming they even know who you are). Getting to know folks is even more important during COVID, but harder.

Li Li is an Assistant Professor leading the Health & Environment Assessment Team (HEAT) at the University of Nevada, Reno since 2019. He obtained his BSc and PhD degrees from Nankai University in 2012 and Peking University in 2017, respectively, and received postdoctoral training at the University of Toronto Scarborough between 2017 and 2019. His research seeks to understand the accumulation, transport, transformation of synthetic chemicals (e.g., flame retardants, plasticizers, pesticides, and surfactants) and materials (e.g., nanomaterials and microplastics) in a nexus comprising the human socioeconomic system, environment, and food webs, as well as the resulting adverse environmental and health effects. He strives to establish, foster, maintain, and promote a variety of mechanistically sound and computationally effective models, to advance our thinking and understanding of the behavior and processes of synthetic chemicals and materials and meanwhile to inform decision making.

Read Li Li’s Emerging Investigator Series article “the role of chemical properties in human exposure to environmental chemicals” and read more about her in the interview below:

Your recent Emerging Investigator Series paper reviewing the role of chemical properties in human exposure to environmental chemicals. How has your research evolved from your first article to this most recent article?

I research various chemical substances manufactured and commercialized by humans and but found to be hazardous to humans and other organisms. For the past years, I have been striving to develop a holistic, mechanistic modeling framework to describe the complete continuum from the production of these chemical substances to their occurrence within the human body. This modeling framework integrates various components such as production, environmental releases, environmental concentrations, exposure, and risks. It allows exploring how human exposure to chemical substances responds to industrial and consumption activities, physicochemical properties of chemicals, features of the environment of interest, and human behavior. I first managed to bridge chemical production, environmental releases throughout the lifecycle, and multimedia environmental concentrations through my doctoral work (compiled as a book entitled “Modeling the Fate of Chemicals in Products” published by Springer). This work was then expanded, during my post-doctoral training, to include the exposure of humans and various ecological receptors, leading to the birth of a comprehensive exposure model named “PROduction-To-EXposure (PROTEX)”. During the most recent year, I continued to extend the chain of models to include toxicity and health outcomes to support assessments of health risks and impacts. This ambitious modeling framework now enables scientists, industrial users, and policymakers to predict what would happen to our environment and health if we decide to manufacture a certain amount of a certain chemical substance; it also allows linking the adverse environmental and health impacts at the current moment back to the regrettable decisions decades ago.

What aspect of your work are you most excited about at the moment?

The interdisciplinarity of my work is the most fascinating. The quantitative characterization of the continuum from chemical production to environmental and health impacts, requires synergistic leveraging of the knowledge and successful experience in environmental chemistry, exposure and health sciences, and industrial ecology. We need systematic understandings of how chemicals move, change, and accumulate in the human socioeconomic system, the physical environment, and the bodies of humans and other organisms. An example is this Emerging Investigators article, which discusses how properties of partitioning, dissociation, reaction, and mass transfer (concepts in environmental chemistry) govern and impact external and internal exposure to various chemical substances (concepts in exposure science). Both environmental chemists and exposure scientists can benefit from reading this paper. I am proud that I am one of the pioneers seeking to fuse these independent research areas and make them interdependent and interconnected.

In your opinion, what are the most important questions to be asked/answered in this field of research?

I think the most important question is to understand how human activities (manufacturing and consumption of chemical substances, behaviors related to chemical intake, measures for mitigating health risks or impacts, etc.) and chemical properties (tonnage, partitioning, reaction, dissociation, mass transfer, etc.) interactively determine human exposure to chemicals and associated health outcomes. Especially, we need a better understanding and characterization of how variabilities in these two aspects (e.g., interindividual variabilities in toxicokinetics, behavior, and toxicological susceptibility, as well as inter-chemical variabilities in partition ratios, half-lives, and mass transfer coefficients) shape the varied human exposure and health outcomes.

Such a systematic understanding is of vital importance because we are exposed to a myriad of chemical substances present in the multimedia environment, released from multiple lifecycle sources, through multiple exposure routes – it is close to impossible to investigate every single chemical case by case. And we also need to identify the most vulnerable and susceptible subgroups of people with disproportionate chemical exposure if we want to protect every single person in our community for environmental justice and fairness.

What do you find most challenging about your research?

The interdisciplinarity also brings about challenges. There has long been a lack of communication and dialog between scientists from these different disciplines. Knowledge and experience are largely compartmentalized and fragmented. For instance, while environmental releases “remain the least understood part of the research” to environmental chemists, industrial ecologists already have a wide range of well-established, mature methodologies on hand for estimating the lifecycle releases of chemical substances. However, since data of environmental releases are not directly measurable or observable, they cannot be evaluated or validated without being converted to concentrations in environmental compartments, which often plagues industrial ecologists due to the lack of fate and transport modeling techniques in industrial ecology. In addition, a common language or knowledge is also missing in many cases. An example is the biotransformation of chemical substances inside the organism body: while its important role in determining bioaccumulation and human dietary ingestion of chemical substances has been very well recognized and characterized by environmental chemists, as reviewed in this Emerging Investigators article, it has yet to be widely accepted by most exposure scientists and/or toxicologists. Also, terminologies and nomenclatures vary among these different disciplines, which adds difficulties to communication and dialog between these research areas. For example, just ask ourselves: what are we talking about when saying “bioavailability”? When using this word, are we really referring to the same thing as an environmental chemist, a toxicologist, an exposure scientist, or a pharmaceutical scientist does?

In which upcoming conferences or events may our readers meet you?

I usually attend the annual meetings of the Society of Environmental Toxicology and Chemistry in North America and Europe. I am also a frequent attendee of the annual meetings of the International Society of Exposure Science.

How do you spend your spare time?

I spend my spare time with my wife, hanging out, watching films and variety shows, and exploring various food and fun. I am also a nice photographer!

Which profession would you choose if you were not a scientist?

I may choose to become a journalist, as I love to investigate the truths beneath the surface and share intriguing stories with others. To me, a scientist is quite similar to a journalist, as they both relay something unknown to the audience through their efforts of exploration.

Can you share one piece of career-related advice or wisdom with other early-career scientists?

It is important to understand both the big picture of the research area and the detailed, fundamental technical skills (e.g., laboratory, modeling, fieldwork, observational methodologies) required in the research area. Vision is crucial to success, but bringing vision into reality is more important. After all, “talk is cheap, show me the data”.

Rachel received her Ph.D. from UC Berkeley in Allen Goldstein’s group and then carried out two postdocs, one at Lawrence Berkeley National Lab and the other at MIT. She started a faculty position in the Chemistry department at William & Mary in 2017 where she is now entering her fifth year. Her research focuses on complex organic mixtures found in aerosol particles and on indoor and outdoor surfaces. With a team of undergraduates and masters’ students, she probes details on the chemical composition and investigates how the mixtures change as they age under natural conditions. Collaborations are a key component of her research, and she is so happy to have had the opportunity to take part in the HOMEChem field campaign to investigate questions in indoor chemistry.

Read Rachel O’Brien’s Emerging Investigator Series article “Chemical and Physical Properties of Organic Mixtures on Indoor Surfaces During HOMEChem” and read more about her in the interview below:

Your recent EmergingInvestigator Series paper focuses on Chemical and Physical Properties of Organic Mixtures on Indoor Surfaces During HOMEChem. How has your research evolved from your first article to this most recent article? 

During my PhD, I explored the chemical composition of aerosol particles using soft ionization and ultra-high resolution mass spectrometry. In my first postdoc I worked on imaging individual aerosol particles using microspectroscopic techniques. During my second postdoc, I helped develop a method to atomize very small sample volumes into an Aerosol Mass Spectrometer. This most recent article is built on all these research skill sets. To fully understand the chemical composition and physical properties of complex mixtures like the ones we look at here, you need a range of different techniques. I’m so fortunate to have had the opportunity to combine my group’s main skill set (chemical analysis) with work from our collaborators to build a full picture of the chemical and physical properties of these indoor films.

What aspect of your work are you most excited about at the moment?

I’m really excited about the aging work that we are doing for complex organic mixtures from biomass burning, secondary organic aerosol, and indoor surface films. Our ability to track chemical changes over longer periods of time is providing some really interesting data sets.

In your opinion, what are the most important questions to be asked/answered in this field of research?

In indoor chemistry I think we really need to understand the chemical mixtures we have both in the surface films, but also in the air. In addition to that, we need to understand the variability that is present since no two houses or workplaces will be the same. With the Pandemic, many of us are spending more time indoors and this begs the questions: what are we breathing and what are we exposed to in these environments? Once we understand all this, we can better design aspects of the built environment, like ventilation and building materials, to improve our health and the quality of our daily life.

What do you find most challenging about your research?

The data sets we generate are complicated and can take long periods of time to analyze. As a pre-tenure faculty member, the slower pace for this can be a bit stressful. But the time we spend pays off in the detailed information we can generate.

In which upcoming conferences or events may our readers meet you?

I will be at AAAR this fall, and I’ll be attending AGU remotely.

How do you spend your spare time?

I don’t find that I have a lot of spare time, but what I do have I spend with my husband Jeremy.  I hope to get back into swimming again once things open back up after the Pandemic.

Which profession would you choose if you were not a scientist?

If I weren’t a scientist, I would want to run a ranch focusing on beekeeping with lots of fields of different native flowers combined with wine fields.

Can you share one piece of career-related advice or wisdom with other early career scientists?

Find good people to work with: people who both encourage you and provide good feedback. Science is a great field to work in when you have a community of fantastic collaborators and mentors to share your journey.