All posts by SETAC Student Outreach

Alexandra Folcik

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Who is Allie? I’m a PhD student in Toxicology at Texas A&M University, Go Aggies!

What’s her research on? My project focuses on the use of electron beam (eBeam) irradiation technology to remediate algal toxins in drinking water.

Why is it important? Rising temperatures and nutrient pollution are increasing the occurrence of harmful algal blooms around the world. When people or animals drink water that comes from a water source containing an algal bloom, they have the potential to ingest toxins, many of which can damage your brain or your liver. Therefore, it is important to find effective ways to get rid of these toxins and organisms from drinking water plants to prevent exposure.

What’s the most fun/rewarding part? The most rewarding part of my research is being able to bridge the gap between so many different disciplines such as engineering, chemistry, and toxicology. The work I am doing has direct applicability to real world problems and could someday be implemented into treatment processes to make the world a healthier place.

Allie has a science highlight on Instagram to talk about her experiments (follow her @ayohkay12)! She is also active on LinkedIn.

Niranjana Krishnan

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Who is Niranjana? I’m a PhD candidate at Iowa State University, which is located in a small but beautiful city called Ames.

What’s her research on? I am studying how agricultural insecticides affect monarch butterflies.

Why is it important? Monarch butterfly populations have been declining and studies have shown that to sustain the eastern monarch population in North America, it is essential to plant milkweed (which is the only plant the monarch caterpillars eat) in agricultural areas in the Midwest. Hence it is important to know how insecticides used in fields harm monarchs so we can plant milkweed in the right locations!

What’s the most fun/rewarding part? I am lucky enough to be one of the few labs which has year-round monarch rearing capabilities — not many people can work on the project I am working on! This makes the data I collect novel. It also helps that federal regulatory agencies, environmental groups, and agrochemical companies are interested in my work.

More details on her research can be found here!

Leah M. Thornton Hampton

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Who is Leah? I’m a PhD candidate at the University of North Texas, though I spend the majority of my time at Texas Christian University!

What’s her research on? My dissertation project is focused on the role of thyroid hormones during the development of the immune system. I’m particularly interested in the potential effects of early life stage thyroid suppression (too little thyroid hormone) on an organism’s ability to defend itself against infections when it is an adult!

Why is it important? It’s important for us to understand how thyroid hormones may impact the immune system because most systems are constantly influencing one another. In other words, we have to understand basic physiology before we can add layers of complexity like how environmental thyroid disruptors may negatively impact the immune system.

What’s the most fun/rewarding part? One of the most challenging/most rewarding parts of my dissertation so far has been tailoring cellular assays to work in my model organism (the fathead minnow). Here you can see me at the microscope counting hundreds of cells as part of this process – tedious, but totally worth it to get the data!

Here are results from her ‘preliminary work’ that inspired this research!

Simplifying ecotoxicology studies with model species: Are organisms in the North hemisphere the same as the organisms from the South?

By Fernando Gastón, Iturburu* and Lidwina, Bertrand*.

Endings are a great opportunity to reflect on past decisions. As both of us wrap up our PhDs in Ecotoxicology (Fernando at the National University of Mar del Plata and Lidwina at the National University of Córdoba, both in Argentina), we keep thinking of the questions we struggled with as students and the conclusions we reached. One of the biggest questions in our research was: is it better to work with native species or model organisms to examine research questions pertaining to aquatic environments in South America?

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Model organisms are simple organisms expected to behave similarly to other organisms when exposed to potentially harmful chemicals. Traditional model species include zebrafish (Danio rerio), aquatic macrophytes of the Myriophyllum and Lemna genera and planktonic crustacean as Daphnia magna among others (Häder and Erzinger, 2018). Model species are well studied, so a lot is known about how to keep them happy and healthy in a laboratory setting. But, most benchmark testing for model organisms was developed in the northern hemisphere, particularly more socio-economically developed countries like the USA, China, Germany, UK, and Canada. Since different species are known to have different sensitivities to toxic compounds (Van der Oost et al., 2003), it is questionable whether or not model organisms can act as representative samples for environmental studies concerning environments in the southern hemisphere.

Our research was concerned with conducting experiments to understand the potential negative impacts of metals and pesticides on South American, particularly Argentinian, aquatic ecosystems. These chemicals can enter the environment from industrial activities such as metalworking, tanneries, litter bins, open sky mega-mining with tons of rocks extracted each year, and large- scale agricultural production which are all common throughout South America. We had several questions while designing our research experiments:

1- Are native species useful (like model ones) to assess environmental degradation through biomonitoring programs?

2- Are studies carried out using species from European or North American countries representative of the sensitivity of species present in ecosystems from others regions of the world?

3- Are the established guidelines developed with model organisms “good” enough to protect species from South American ecosystems?

4- Could we develop our own guidelines with native species?

We were ultimately swayed to using multiple local species (shown in Figures 1 and 2) because we believe, along with the experts of the OECD (Organization for Economic Co-operation and Development, 2002), that multiple indigenous test species provide more robust results for resolving regional environmental concerns.  But this decision came with several advantages and disadvantages. Let’s start with the “worst” part of the story, the disadvantages of working with native species:

– The first problem is the absence or low availability of basic information about your object of study. Since no one else is studying them, there’s a lot more uncertainty in understanding how chemicals affect them. There is also little information about how to keep them healthy in a laboratory setting so it is hard to say if observations are caused by chemicals or just abnormal living conditions. Resolving this concern involves a lot of time, money, and resources (which are sparse when you’re a PhD student!) which can limit your experimental design and, sometimes, lead to make mistakes or to obtain non “suitable” results.

– Other problem arise when you try to publish your first paper and reviewer’s comments arrive in your inbox. Comments reflect great distrust in your results, even if standardized protocols were applied, because you are not using a model species. This leads some reviewers to doubt the usefulness of your research because is not a world recognized model and concern.

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Figure 1- Australoheros facetus is a cichlid fish which inhabits the Parana’s basin in Brazil, Paraguay, Argentina, and Uruguay. It is a suitable and sensitive fish species to assess pesticides pollution in South American ecosystems. Ph: Fernando G. Iturburu.

But not everything is negative when you chose a native species to join you and your Ph.D. thesis for three or five years. Several advantages to using native species are:

– Usually, the “native” characteristic allows for better availability and accessibility to organisms for experimental tests. They don’t have to be shipped too far, and could even be collected close to your lab!

– You can avoid the introduction of exotic organisms into local waters when conducting field studies with foreign model organisms, which has the potential to cause serious ecosystems disorders.

– The lack of information about native species can also be considered a positive: ALL is new and the obtained information will improve the understanding of the sensitivity of these species and related ones, and how regional ecosystems would be affected in presence of pollutants. New biological mechanisms and responses can be found and published but, again, tips about how to communicate your research work are crucial! You must convince reviewers that non-model species results represent a novelty important for advancing global ecotoxicological knowledge.

– Results from native species studies would be considered for the selection of new, region-specific model species to use in the establishment of environmental guidelines of studied region, which could improve the protection of aquatic ecosystems.

When comparing results from our research to the existing body of literature, we found the advantages to outweigh the disadvantages. The literature describes that the LC50 (concentration at which 50 percent of organisms in a study exposed to a compound die) for the neonicotinoid insecticide imidacloprid in model fish is around 200 mg L-1 (IUPAC PPDB, 2018). Nevertheless, for the South American cichlid fish Australoheros facetus (Figure 1), we found that the LC50 value was much less: below of 10 mg L-1 (Iturburu et al., 2017)! Even more, this compound causes DNA damage from concentrations of 1 μg L-1 (Iturburu et al., 2018, remember that 1 microgram (μg) is a millionth part of 1 gram).

Figure 2- Palaemonetes argentinus represents a small decapod from water ecosystems of South America. Its sensitivity to pollutants exposure as well as its ecological relevance in trophic chains and, ecosystems, led to it being proposed as a possible bioindicator of environmental quality. Ph: Lidwina Bertrand.

We also found interesting results with respect to variability in sensitivity across organisms. For example, the Argentinean Environmental Water Quality Guidelines (AEWQG, 2003) recommends concentrations of the widely used insecticide chlorpyrifos (CPF) should not exceed 6 ng L−1 (being 1 nanogram, ng, a billionth part of one gram) for the protection of aquatic biota. This limit comes from experimental results with model species from others world regions. Nevertheless, the shrimp Palaemonetes argentinus (Figure 2) and the macrophyte Potamogeton pusillus showed significant response of studied biomarkers after 96hs of exposure at 3.5 ng L−1! In the case of the shrimp, several biomarkers responded significantly at 3.5 ng L−1 CPF, including metallothionein concentration (decreased), acetylcholinesterase (inhibited) and antioxidants enzymes (induced) activities; while in the macrophyte chlorophylls contents dropped in described conditions (Bertrand et al., 2016 and 2017). Usefulness of native species as bioindicators of water pollution was evidenced using them in river monitoring campaigns (Bertrand et al., 2018 a, b).  So, all these results (and many others) which show that different species can still be affected at different concentrations of a chemical, even below an accepted limit, telling us that species selection in ecotoxicology testing is very important.

Thus, the native species have a lot of information to bring us, and from our place (and with all necessary considerations) we will continue to promote the use of these organisms to understand the possible effects of pollution in South American and others ecosystems. And maybe one day (who knows!), we will be able to have our own model species and guidelines.

 

 

Blogpic-5Iturburu, Fernando Gastón obtained his Ph.D. in Biological Sciences at the National University of Mar del Plata, Argentina. His research focused on the effects of current use pesticides on two South American freshwater species: a cichlid fish (Australoheros facetus) and a macrophyte (Myriophyllum quitense). The thesis aimed to study different biomarkers of these organisms experimentally exposed to pesticides, as well as study factors which could modify the interpretation of these responses. As an ultimate goal, the project aimed to establish these organisms as freshwater bioindicators in South American aquatic ecosystems. Publications from PhD thesis can be found in:

https://www.researchgate.net/profile/Fernando_Iturburu

E-mail: fernando.g.iturburu@gmail.com

 

Blogpic-6Bertrand, Lidwina obtained her Ph.D. in Biological Sciences at the National University of Córdoba, Argentina. Her research focused on the usefulness of two South American native species, a small shrimp (Palaemonetes argentinus) and a rooted macrophyte (Potamogeton pusillus), as freshwater bioindicators. The thesis involved firstly the study of biomarkers responses in mentioned organisms exposed to environmentally relevant concentrations of pollutants (metal and pesticide) laboratory conditions. Experiments involved exposure concentrations lower than those suggested by Argentinean environmental guidelines. Finally, organisms were used in an active monitoring with the aim to analyze their sensitivity in sites with complex mixture of pollutants associated with different land uses in the Ctalamochita River Basin as a case of study.  Publications from PhD thesis can be found in:

https://www.researchgate.net/profile/Lidwina_Bertrand

E-mail: lidwinabertrand@gmail.com

 

References

– AEWQG (Argentinean Environmental Water Quality Guidelines), 2003. Subsecretaria de Recursos Hídricos de la Nación, República Argentina.

– Bertrand, L., Monferrán, M.V., Mouneyrac, C., Bonansea, R.I., Asis, R., Amé, M.V., 2016. Aquat. Toxicol. 179, 72–81. http://dx.doi.org/10.1016/j.aquatox.2016.08.014

– Bertrand, L., Marino, D.J., Monferrán, M.V., Amé, M.V., 2017. Environ. Exp. Bot. 138, 139–147. https://doi.org/10.1016/j.envexpbot.2017.03.006

– Bertrand, L., Monferrán, M.V., Mouneyrac, C., Amé, M.V., 2018a. Chemosph. 206, 265–277. https://doi:10.1016/j.chemosphere.2018.05.002

– Bertrand, L., Monferrán, M.V., Valdés, M. E., Amé, M.V., 2018b. Env. And Exp. Bot. Under revision.

– Häder, D. P. and Erzinger, G. S., 2018.  Bioassays: Advanced Methods and Applications. Elsevier. https://doi.org/10.1016/B978-0-12-811861-0.00031-0

– Iturburu, F.G., Zömisch, M., Panzeri, A.M., Crupkin, A.C., Contardo-Jara, V., Pflugmacher, S., Menone, M.L., 2017. Ecotoxicol. Toxicol. Chem. 36(3), 699-708. https://doi.org/10.1002/etc.3574.

– Iturburu, F.G., Simoniello, M.F., Medici, S., Panzeri, A.M., Menone, M.L., 2018. Bull. Environ. Contam. Toxicol. https://doi.org/10.1007/s00128-018-2338-0.

– International Union of Pure and Applied Chemistry (IUPAC). PPDB: Pesticides Properties DataBase. University of Hertforshire, Hatfield, Hertfordshire, UK. [cited 2018 April 19]. Available from: http://sitem.herts.ac.uk/aeru/iupac/atoz.htm.

– OECD (Organization for Economic Co-operation and Development). Testing guidelines. Available from: http://www.oecd.org/env/ehs/testing/

– van der Oost, R., Beyer, J., Vermeulen, N.P.E., 2003. Environ. Toxicol. Pharmacol. 13, 57–149, http://dx.doi.org/10.1016/S1382-6689(02)00126-6.

Why we Need a Science-Based Approach to Help the Monarch Butterflies

By Niranjana Krishnan

I will start by acknowledging this: I am lucky to be working with monarch butterflies. Not only are they fascinating and beautiful, very few labs in the country have colonies to run year-round bioassays. At Iowa State University, where I am a PhD student, the colonies are maintained by the U.S. Department of Agriculture (USDA).

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USDA’s monarch butterfly colony in Ames, Iowa

There are several factors that make monarchs captivating species: their four-stage life cycle, their annual passage across North America, their reproductive diapause (i.e., suspension of mating) before migration to overwintering sites, and so on. As you can find all this information easily online, I will stick to something which isn’t written or published anywhere (yet!): my research. I assess the risks of insecticide exposure on monarch butterfly larvae. Before I delve more into this exciting work, I would like to explain why it is important and what can be achieved with this research.

In the US you see two major migratory populations, one to the east of the Rocky Mountains and the other to the west. Both populations have declined by nearly 80% in the last two decades¹. In response to this, U.S. Fish and Wildlife Service (USFWS) was petitioned to list the monarchs as endangered species. The agency will come up with a listing decision in June 2019², but in the meantime released a working document that stressed the need to know risks of insecticide exposure on the butterfly³. The decline also made then President Obama specifically include monarch butterflies in his Pollinator Memorandum, where he tasked the U.S. Environmental Protection Agency (USEPA) and USDA to restore their populations⁴. One of the major reasons for the butterfly decline is believed to be the loss of milkweed⁵- the only food the caterpillars eat. Thus, conservation efforts are focused on planting milkweeds, especially in Iowa and the neighboring Midwestern states, which form the summer breeding grounds of the eastern monarch migratory population. As these states also have large swaths of land devoted to agriculture where insecticides are often used, there is a concern that planting milkweeds in such landscapes could negatively impact larval survival and adult recruitment. Because of this concern, USDA issued a guideline discouraging milkweed establishment within 125 feet of insecticide-treated crop fields⁶. For a representative county in Iowa, we found that this ‘no plant zone’ would exclude over 80% of rural roadside rights-of-ways and nearly 40% of non-crop lands. That is a lot of area being lost where potential habitat could go. And unfortunately, there is very little monarch toxicology or exposure data to know at what distances to plant milkweeds away from insecticide-treated fields.

And that’s what my lab is trying to find out! We selected insecticides commonly used in corn and soybean fields, as they are the predominant crops grown in the midwestern states. Our six representative insecticides cover four different groups based on modes of action: pyrethroid, organophosphate, neonicotinoid and anthranilic diamide. In corn and soybean fields, these insecticides are either sprayed or coated on the seeds. If they are sprayed, they can drift and land on nearby milkweeds or larvae. If they are coated on seeds, they can leach into the soil and be absorbed by milkweeds downslope of the crop field. Thus larvae can be either directly exposed to insecticides through their cuticle or indirectly exposed by consumption of milkweed leaves. Our toxicology bioassays mimic these two routes of exposure.

To figure out at what distances to plant milkweeds from crop fields, we are doing the following:

  1. Determining the toxicity of insecticides on the larvae by generating dose-response curves, i.e., finding concentrations that cause a spectrum of mortality (0% to 100%).
  2. Estimating exposure concentrations that the larvae are likely to face at different distances from treated fields (the further away they are, insecticide exposure will decrease). We rely on computer models and field studies to obtain this information.
  3. Using the dose-response curves and exposure estimates to calculate larval percentage mortality at different distances away from the field. This is called a patch-scale risk assessment.
  4. Incorporating the above information into an agent-based model⁷ to see how the monarch population responds at the landscape level. This is called a landscape-scale risk assessment and it is more realistic and informative than a patch-scale risk assessment since monarch butterflies fly across the landscape and lay one or two eggs on milkweed stems here and there. They don’t lay all their eggs in one basket!

The final step can help answer questions like how many monarchs would be produced with and without a ‘no plant zone’ (125 feet or otherwise) over a ten-year period in Iowa. Based on our data, the habitat placement option that produces the most monarchs can hopefully be implemented on the ground.

So far, we have obtained comprehensive results for spray applications where the insecticide directly lands on larvae. Based on our toxicology studies, pyrethroid (beta-cyfluthrin) and anthranilic diamide (chlorantraniliprole) insecticides cause the greatest mortality, followed by organophosphates (chlorpyrifos). Neonicotinoids (imidacloprid and thiamethoxam) cause negligible mortality, especially to older larvae. The larval mortality away from the field is much greater if the insecticide is applied via an aircraft as compared to ground applications⁸. Based on our landscape modeling data so far, more adult monarchs are produced by planting milkweeds in all available space as compared to scenarios with 125 feet ‘no plant zone’ around corn and soybean fields, even with the larval mortality due to spray drift⁹. Our ongoing studies are looking at how larval consumption of milkweeds that contain insecticides can influence monarch production and inform options for placement of new habitat.

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Niranjana Krishnan is obtaining a doctorate degree in toxicology from the entomology department at Iowa State University. She is a student member of Iowa Monarch Conservation Consortium (https://monarch.ent.iastate.edu/).

 

References:

  1. Brower L.P., Taylor O.R., Williams E.H., et al (2012) Decline of monarch butterflies overwintering in Mexico: Is the migratory phenomenn at risk? Insect Conserv Divers 5:95–100.
  2. https://www.fws.gov/savethemonarch/SSA.html
  3. https://www.fws.gov/savethemonarch/pdfs/Monarch.pdf
  4. https://obamawhitehouse.archives.gov/blog/2015/05/19/announcing-new-steps-promote-pollinator-health
  5. Flockhart DTT, Pichancourt JB, Norris DR, Martin TG (2015) Unravelling the annual cycle in a migratory animal: Breeding-season habitat loss drives population declines of monarch butterflies. J Anim Ecol 84:155–165. doi: 10.1111/1365-2656.12253
  6. National Resources Conservation Service (NRCS) Monarch Butterfly Wildlife Habitat Evaluation Guide (2016)
  7. Grant T., Parry, H., R., Zalucki, M.J., and Bradbury, S.P. (2017) Predicting monarch butterfly movement and egg laying with a spatially-explicit agent-based model: The role of monarch perceptual range and spatial memory. Ecological Modelling (Submitted).
  8. Krishnan, N., Bidne, K., Hellmich, R., Coats, J. and Bradbury, S.P. (2017) Risk assessment of insecticides commonly used in corn and soybean production on monarch butterfly (Danaus plexippus) larvae.  Society of Environmental Toxicology and Chemistry North America 38th Annual Meeting. November 12 -16, Minneapolis, MN (Abstract ID# TP106).
  9. Bradbury S.P., Grant, T.J., Krishnan, N. (2017) Landscape Scale Estimates of Monarch Butterfly (Danaus plexippus) Population Responses to Insecticide Exposure in an Iowa Agroecosystem. Society of Environmental Toxicology and Chemistry North America 38th Annual Meeting. November 12 -16, Minneapolis, MN (Abstract ID# 182).

 

The Arctic was not what I expected

By Neal Bailey

I was surprised from the moment I stepped off the bush plane. No exposed rock, snow, or cold winds. Instead, a sunny and warm stretch of flat, mossy soil extended to a low crest of hills ahead. There were a handful of fuel barrels placed strategically across the landscape as markers – an attempt to impose some sort of border on the landscape. There was a cabin – Green Cabin; a single room with a table, some supplies, and a small camp oven. Everything else was the Arctic summer- the blaze of a sun that swung overhead in a perpetual arc. I hadn’t read that it would be hot. I had, however, read about the mosquitos. They saw us, correctly, as their only chance for blood, and I applaud their persistence. Persistence, in the Arctic, is key.

 

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Banks Island – Location of the Thomsen River

 

Aulavik sees few visitors; in a typical year, perhaps a dozen people set foot there. Usually, these few are either Parks Canada employees on a survey, or people looking for a chance to canoe up the most northerly navigable river in North America. The costs and conditions involved are both forbidding – planes need to be specially chartered, supplies need to be carried, and the terrain is vast and almost playfully unfriendly. The sheer isolation of the place is what makes it interesting to a scientist; here we have a corner of the world almost as far from human impacts as possible, and yet still the shadows of our influence loom. Each year, the winter grows softer and the summer season longer. The northern reaches of the Thomsen valley looked more like Scottish highlands than a classical Arctic scene; rolling terrain draped in bright green. Rain falls constantly, a stark contrast to the Arctic desert pictured in textbooks.

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Thomsen River Bank
surprisingly green 2
Grassy hillsides in northern Aulavik Park

As a researcher, I’d come to Aulavik to look at permafrost slumps, and how they chemically impact the aquatic ecosystem. The damage is obvious – jagged scars of black earth run down the sides of mountains, draining into muddy riverbanks below. It’s visible from miles away. What’s less visible is what is actually in the slumps. The clear water of the Thomsen River flows brown for kilometers downstream of the muddy wounds, but without samples to analyze, such descriptions are meaningless. So, we began a canoe trip spanning over 100 km, riding the Thomsen as it rolls into the Arctic Ocean.

Soils provide records of the past, and the sediments of Aulavik, locked in permafrost, tell a history different from the rocky spars of the eastern Arctic. Southern soils are sandy, dull and pale brown, whereas the northern reaches of the park darken to near black. Mounds of vegetation give way underfoot, releasing pools of tea-colored water in each footprint; in moments, those footprints vanish as the ground springs back, seemingly eager to erase any trace of our presence. Strange patterns of narrow gullies and raised hillocks stretch across the valleys, interspersed by shallow, dark lakes. No one has ever cultivated these lands, and nobody is sure what’s in the ground. This is why we need to gather samples from both the soil itself and the water in tandem.

slumps in the distance
Black streaks of visible permafrost slumping in Aulavik Park

Sample gathering for trace metals in water is challenging. Out in the field, in the snow and wind, there can be many complications. We needed two people for the clean hands-dirty hands protocol – one person is ‘clean hands’ and is the only one who comes into direct contact with the sampling environment, the samples themselves, and the containers that hold the samples. The other is ‘dirty hands’, and is responsible for handling more or less everything else. This method is designed to avoid contamination at all costs, and under harsh conditions it’s absolutely necessary to make sure everything is done properly. The biggest complication was never the weather, but the ‘wildlife’: when the temperature got above 6 degrees or so, bugs would start appearing, like some strange haze rising from the soil.

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Water sampling in southern Aulavik Park

Thankfully it was usually too cold (we were in Canada’s coldest spot for a while there!) but when they could fly, they would fly into everything: sample bottles, gloves (as you’re putting them on), clothes, hair, ziplock bags, open mouths.

Permafrost cores were also collected. Depending on what’s in the permafrost, there are a huge variety of ways the slumps could impact the waters. Heavy metals such as mercury could find their way into phytoplankton, the base of the food chain. Mercury in particular can be methylated via bacterial processes and then easily sequester itself into basal biota, at which point it poses a risk to more complex forms of life further up the food chain [1]. Mercury was suspect number 1 in the tests we conducted.

Tests are ongoing, but initial analysis reveals a pristine river, with minimal mercury impacts in even the densest slumps. This, at least, is good news for the ecosystem. So far. Only total mercury concentration has been examined to date, and mercury’s toxicity varies drastically depending on speciation. Of key interest are organo-mercury compounds, which are not only very toxic but tend to sequester in tissue and biomagnify up the food chain [2,3]. Depending on the methyl mercury (and to a less extent dimethyl mercury, which usually degrades into methyl mercury in situ), the river’s fish population may have excessive mercury loads.

On the carbon side, chemical changes are obvious; the volume of soil and nutrients draining into the river from the permafrost melt is massive. Organic carbon compounds form the bedrock for all manner of food webs in natural waters, but whether this is good news or not is up for debate. Rapid changes in fragile, easily disturbed ecosystems have a habit of causing problems, even if it would at first appear that a simple equation of more food equals more productive river would apply. As we look into the specifics of the system, we can hopefully answer questions about the river’s health and apply them to similar Arctic ecosystems, many of which are changing rapidly today.

Neal Bailey studies environmental chemistry at University of Manitoba. Previously a writer, he was drawn to environmental science both for its contemporary relevance, and the option to work in both laboratory and natural environments.

References

  1. Chasar et al; Mercury Cycling in Stream Ecosystems. 3. Trophic Dynamics and Methylmercury Bioaccumulation; Environmental Science and Technology (2009), Vol 43 Issue 8 pp 2733-2739
  2. Morel F. M. M., Kraepiel A. M. L., Amyot M.; The Chemical Cycle and Bioaccumulation of Mercury; Annual Review of Ecology and Systematics (1998), Vol 29 pp 543-566
  3. Mason R. P., Reinfelder J. R., Morel F. M. M.; Bioaccumulation of Mercury and Methylmercury; Water Air and Soil Pollution (1995), Vol 80 Issue 1-4 pp 915-921

Our Role in Combating Pseudoscience

By Mandy McDougall

The prevalence of pseudoscience in our society is getting out of hand.

Pseudoscience (including bad science, chemophobia, and full-fledged anti-science) presents itself as a multidisciplinary problem. Though many pseudoscientific claims concern personal and public health (for instance, vaccines and vaccine-preventable diseases, homoeopathy, and ‘detox’ cleanses), some also concern environmental toxicology, including misconceptions surrounding many environmentally relevant compounds, such as pesticides. Although pseudoscience is by no means a new phenomenon, tea detox advertisements and chemtrail conspiracy theory pages are now polluting the internet and social media. When combined with the growing glorification of pursuing ‘alternative’ agricultural and medical practices, pseudoscience often tries to disguise itself as quality science.

Such frequent disregard of the scientific method calls for scientists – particularly toxicologists – to play a vital role in tackling pseudoscience. Those who understand the science have an obligation to passionately and unapologetically communicate the threats of pseudoscience as it relates to public health, food security, and scientific literacy. How many times have you seen ads for a ‘chemical-free’ dish soap, granola bar, or makeup powder? Seems innocent enough, but excusing bad science in marketing is just the beginning of something much worse.

Overall, this issue is bigger than the specific area of toxicology or chemistry that we study. People are being encouraged to put their families, their children, and public health at risk, on account of advice from sources claiming to be an enlightened alternative to the evil ‘Bigs’ – Big Pharma, Big Ag, Big Chem – you get the picture.

Some people have adopted a reaction whereby they believe that any product developed by a large company – let’s say pesticides – is inherently bad. No questions asked; no case-by-case evaluation; no room for logic and reasoning. These knee-jerk reactions to words like ‘pesticide’ and ‘chemical’ are brought on by fear-mongering campaigns and clever marketing schemes for ‘alternative’ products. There is this unfounded assumption that in maintaining a healthy environment, the use of conventional pesticides cannot occur. However, these two things are not, as some may think, mutually exclusive.

Perhaps the most well-known example of this involves the continued use of DDT (dichlorodiphenyltrichloroethane) in select tropical regions of the world. DDT was once believed to be completely safe for widespread application. However, we eventually learned about the long-term bioaccumulative and toxic effects related to DDT exposure in ecosystems, wildlife, and humans.

Despite these serious toxicological concerns, DDT is still approved for use in certain regions of the world in an effort to combat malaria. Such decisions are the result of complex risk assessments. When the benefits of DDT’s anti-malaria properties are weighed against the adverse long-term bioaccumulative and toxic effects of exposure to the compound, DDT use wins in some cases, but not in others. It is important to remember that the world is full of wicked problems where there fails to be one ‘right’ solution. In such cases, pragmatic problem solving prevails over ideological thinking. In environmental decision-making, a one-size-fits-all solution is often unachievable. We must look at the evidence and calculate the potential benefits and costs via the risk assessment process.

That being said, an important question to ask someone standing firm in their anti-science or pseudoscientific position is, “What would it take to change your mind on this issue?”, whether it be vaccine safety, the impracticality of detox cleanses, or agrochemicals. To someone who is concerned about the potential effects of a herbicide like glyphosate, you may, as an environmental toxicologist, want to challenge their claim that glyphosate is inherently a ‘bad chemical’. You may explain the role of route and exposure in estimating the risk of toxic effects from pesticides and herbicides. You may explain to them what it actually means when something is labelled as a ‘probable carcinogen’. You may explain how the International Agency for Research on Cancer (IARC), like most organizations, has their own agenda.

If nothing you say could ever make them even consider a different perspective, it means that they are no longer thinking in terms of scientific truth, but simply in their beliefs. Their belief that ‘chemicals are bad for the environment’ is no different from other types of beliefs. No amount of scientific data could change their perspective on ‘chemicals’. Ultimately, such beliefs stem from a lack of knowledge in chemistry and toxicology. Although they may consider themselves enlightened because they believe in information contrary to ‘mainstream science’, this does not mean that what they believe is legitimate.

It is likely that some of this mistrust stems from a lack of transparency and effective communication on behalf of regulators and environmental scientists. We will have to first overcome this lingering mistrust between scientists and the public. Twitter feuds and debates just seem to further divide the ‘conventional’ and ‘alternative’ science communities. To promote effective communication, advanced facilitation techniques are probably necessary. The main objective here should be to search for an idea or statement that both an agrochemical scientist and environmental activist could agree on. For instance, perhaps a statement like, “Pesticides have the potential to harm the environment and those who live within it” may be appropriate. I’m sure that there are situations in which both parties would believe this to be true. Once some common ground is established, subsequent conversations will likely be less defensive and circular.

Environmental pollution has been and continues to be, detrimental to the air, water, soil, and well-being of many communities worldwide. From biomagnification of harmful contaminants in Northern communities to hydrocarbon pollution at abandoned gas stations, environmental pollution is prevalent and a constant threat to humans, wildlife, and ecosystems. I began studying environmental toxicology because of my love for nature and the desire to protect the environment against anthropogenic harm – from a rational, scientific approach. Without this, we cannot know where to prioritize our efforts and would be easily distracted by the claims of pseudoscience enthusiasts.

I end with a plea. My plea to students studying environmental chemistry and toxicology is to speak up for sound science. Being a scientist does not disqualify us from sharing knowledge outside of an academic journal or a conference poster. If anything, we should feel compelled and eager, if not obliged, to contribute to such conversations.

Don’t let companies get away with marketing ‘chemical-free’ products. Don’t let your friends spread misinformation from websites with questionable agendas. It might seem innocent enough, but it’s these same ideas that influenced parents, in several instances, to attempt to cure their children’s very treatable diseases using pseudoscientific approaches, sadly resulting in their death. At some point, an innocent lack of scientific literacy grows to become a danger to public health, food systems, and the overall integrity of science. So for me, this is no longer just about silly semantics. It’s about our role in shaping a society equipped to interpret and challenge information.

McDougall

 

Mandy is a graduate student at Simon Fraser University studying bioaccumulation behaviour of perfluorinated compounds in marine food webs.

Our World at the Nanoscale

By Alexis Wormington

What are nanoparticles?

Nanoparticles are particles with at least one dimension sized on the nanoscale, which is usually defined as 1-100 nanometers1 (Figure 1). Put in simpler terms, nanoparticles are very small.

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Figure 1. The nanoscale2

Nanoparticles are on the same scale as many biomolecules, including antibodies, proteins, and sugars. We can’t see them, but, just like bacteria, they’re all over the place!

Where do nanoparticles come from?

Nanoparticles occur naturally in the environment – common sources include volcanic ash, ocean spray, dust, and sand3. Researchers are primarily interested in nanoparticles of synthetic (man-made) origin. Synthetic nanoparticles can be unintentional by-products of many commercial processes or intentionally synthesized for a variety of technological and industrial applications4. The latter are commonly referred to as engineered nanoparticles or engineered nanomaterials.

How do we use nanoparticles?

There are hundreds of different types of nanoparticles, and researchers are constantly engineering new ones in order to expand and invigorate the field of nanotechnology. Nanoparticles can be produced from a variety of elements, including carbon and metals such as titanium, gold, and silver.

Nanoparticles are interesting and useful because they have unique thermal, chemical, and optical properties compared to their larger, bulk elemental counterparts. These properties lend to a variety of applications, including those in the medical, environmental, engineering, technology, and commercial industries. Nanoparticles are often used as conductors in circuits and displays in electronic devices5, in textiles to improve or add functionalities (such as bacterial resistance, breathability, and strength6), as targeted drug-delivery vehicles in many cancer therapies7, and in environmental remediation efforts to bind and neutralize toxins.8

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Figure 2. The many applications of nanotechnology9.

In other words, nanoparticles are everywhere! For example, the active ingredient in most SPF (sun protection factor) cosmetics is zinc or titanium dioxide nanoparticles. Soon, carbon nanotubes will replace silicon as semi-conducting transistors inside of our computers and smartphones. Some make-up products even contain gold nanoparticles!

Nanoparticles sound awesome – should we be concerned about them?

In the last ten years, the presence of nano-enabled (contains nanoparticles or nanoscale materials) products on the consumer market has increased exponentially. The Project on Emerging Nanotechnologies works on documenting nano-enabled consumer products in something called a Consumer Products Inventory (CPI). As of 2014, the CPI lists 1814 nano-enabled products currently available on the consumer market, compared to just 54 products listed in 200510. That’s an average increase of 362% every year!

A consumer market full of nano-enabled products means that nanoparticles and nanomaterials will inevitably end up in the surrounding environment – which means the water we drink and the air we breathe. The Environmental Protection Agency is currently researching the “most prevalent nanomaterials that may have human and environmental health implications”, which includes silver nanoparticles, carbon nanotubes, cerium and titanium dioxide, iron nanoparticles, and copper nanoparticles11.

The health implications of exposure to nanoparticles vary depending on the type of particle and the route of exposure, but researchers have proposed that nanoparticles smaller than 10 nm can enter biological tissue12. Silver nanoparticles, utilized commonly in the textile industry for their antibacterial properties, release silver ions which are associated with mitochondrial and oxidative damage in both vertebrates and invertebrates13. A famous pilot study published in Nature Nanotechnology in 2008 found that commercially available carbon nanotube fibers induced mesothelioma-like pathologies in the abdominal cavity of mice due to their structural similarity to asbestos14. Copper oxide nanoparticles, used not only as a semi-conductor but as the active spermicide in many intrauterine devices (a form of long-term birth control), are associated with multiple organ-level effects in experimental organisms15.

There are many organizations around the world that specialize in nanosafety research. These research groups focus on understanding the behavior of nanoparticles throughout the life cycle (manufacturing, product use, and disposal) in order to determine whether they pose a potential threat to humans or the environment11. This can be a daunting task – because some types of nanomaterials are more harmful than others, and some exposure scenarios are more relevant than others (i.e. inhalation versus ingestion versus injection). Nanoparticles are also maddeningly difficult to detect, which makes studying them a headache! For example, detecting carbon nanotubes in biological tissues is often described as “searching for a carbon needle in a carbon haystack”, and detection methods are still being optimized. Detection methods vary for different types of nanoparticles and range from microscopic methods (such as transmission electron microscopy), to light scattering methods, to spectroscopy techniques, to x-ray based methods16. Often times, researchers will send their samples off to another lab for quantification, because they simply do not have the proper equipment at hand!

Nanoparticles, while useful and incredibly versatile, should be approached with caution. The research on them is still in the preliminary stages, and there is still much we do not know about their potential effects on human and environmental health. As the field of nanotechnology grows, it is important to remain informed and vigilant to ensure that these particles are used safely and efficiently.

alexis


Alexis Wormington
is a PhD Student at the Center for Environmental Toxicology & Chemistry at the University of Florida. Her research is focused on the toxicity of nanomaterials in aquatic ecosystems.

 

References 

  1. “Nanomaterials.” National Institutes of Environmental Health Sciences. National Institute of Health, n.d. Web. 11 Jan. 2017.
  2. Tarafdar, J.C., Adhikari, T. (2015). Nanotechnology in Soil Science. In Ratten, R.K. et al (Eds.), Soil Science: An Introduction (pp 775-807).
  3. Lohse, Sam. “Nanoparticles Are All Around Us.” Blog post. Sustainable Nano. Center for Sustainable Nanotechnology, 25 Mar. 2013. Web. 11 Jan. 2017.
  4. org. “The Future Belongs to Nano.” Omni Nano – The Curriculum to Inspire the Scientists, Entrepreneurs and Engineers of Tomorrow! N.p., n.d. Web. 03 Feb. 2017.
  5. Bhatia, S., Raman, A., & Lal, N. (2013). The shift from Microelectronics to Nanoelectronics: a review. Internat J Advanc Res Comp Communic Engin, 2, 11.
  6. Rivero, P. J., Urrutia, A., Goicoechea, J., & Arregui, F. J. (2015). Nanomaterials for functional textiles and fibers. Nanoscale research letters, 10(1), 501.
  7. Salata, O. V. (2004). Applications of nanoparticles in biology and medicine. Journal of nanobiotechnology, 2(1), 3.
  8. Khin, M. M., Nair, A. S., Babu, V. J., Murugan, R., & Ramakrishna, S. (2012). A review on nanomaterials for environmental remediation. Energy & Environmental Science, 5(8), 8075-8109.
  9. Buzea, C., Pacheco, I. I., & Robbie, K. (2007). Nanomaterials and nanoparticles: Sources and toxicity. Biointerphases, 2(4), MR17-MR71.
  10. Vance, M. E., Kuiken, T., Vejerano, E. P., McGinnis, S. P., Hochella, M. F., Jr., Rejeski, D. and Hull, M. S. (2015). Nanotechnology in the real world: Redeveloping the nanomaterial consumer products inventory. Beilstein Journal of Nanotechnology, 6, 1769-1780.
  11. “Research on Nanomaterials.” EPA. Environmental Protection Agency, 18 Oct. 2016. Web. 11 Jan. 2017.
  12. Bahadar, H., Maqbool, F., Niaz, K., & Abdollahi, M. (2015). Toxicity of Nanoparticles and an Overview of Current Experimental Models. Iranian biomedical journal, 20(1), 1-11.
  13. Stensberg, M. C., Wei, Q., McLamore, E. S., Porterfield, D. M., Wei, A., & Sepúlveda, M. S. (2011). Toxicological studies on silver nanoparticles: challenges and opportunities in assessment, monitoring and imaging. Nanomedicine, 6(5), 879-898.
  14. Poland, C. A., Duffin, R., Kinloch, I., Maynard, A., Wallace, W. A., Seaton, A., … & Donaldson, K. (2008). Carbon nanotubes introduced into the abdominal cavity of mice show asbestos-like pathogenicity in a pilot study. Nature nanotechnology, 3(7), 423-428.
  15. Bahadar, H., Maqbool, F., Niaz, K., & Abdollahi, M. (2015). Toxicity of Nanoparticles and an Overview of Current Experimental Models. Iranian biomedical journal, 20(1), 1-11.
  16. López-Serrano, A., Olivas, R. M., Landaluze, J. S., & Cámara, C. (2014). Nanoparticles: a global vision. Characterization, separation, and quantification methods. Potential environmental and health impact. Analytical Methods, 6(1), 38-56.

How I ended up in the Arctic

By Sara Pedro

I became interested in contamination of the polar regions during my master’s while researching mercury concentrations in Antarctic Gentoo penguins (Pygoscelis papua). This species spends their complete life cycle in many of the sub-Antarctic islands, such as South Georgia and the Kerguelen Islands, and reproduce in colonies of about 320 000 breeding pairs (Borboroglu and Boersma 2013). Because of their large numbers, wide distribution in the Antarctic Ocean, and easy access, Gentoo penguins are good biomonitors of local contaminant concentrations; a major reason we studied this species. We found that mercury concentrations in Gentoo penguins were not at concerning levels (Pedro et al. 2015). Nevertheless, the fact that mercury accumulates in species in the Antarctic, one of the most remote regions in the world, indicates the widespread contamination of pollutants released mostly in industrialized areas.

In transitioning to my PhD, I switched poles to focus on the Arctic. Like in the Antarctic, the Arctic region is impacted by global pollution. At the same time, the Arctic has been facing marked sea-ice loss associated with increasing temperatures. The Arctic is more susceptible to these changes in climate than other regions around the globe (Screen and Simmonds 2010) due to the albedo effect: less sea-ice to reflect solar radiation leads to more absorption by the ‘darker’ ocean surface. Because contaminants are transported by air and oceanic currents, climate change will likely alter contaminant dynamics and pathways into Arctic ecosystems (Macdonald et al. 2005). One situation that leads to this change in contaminant dynamics is the alteration of Arctic food web structure, such as the replacement of native with invasive prey fish.

My current PhD project at the University of Connecticut focuses on legacy persistent organic pollutants (POPs) and mercury in invasive versus native prey fish in the Eastern Canadian Arctic, and consequent levels in ringed seals (Pusa hispida). Legacy POPs include several pesticides and polychlorinated biphenyls (PCBs) that can travel long distances, often by atmospheric transport, eventually accumulating in remote regions. These POPs take a long time to break down in the environment, and can accumulate in animals to potentially cause toxic effects (Letcher et al. 2010). Mercury is released mainly during gold mining and coal burning and is transported to remote regions where, similarly to POPs, it can accumulate in the food web and cause toxic effects (Dietz et al. 2013).

With the recent increases in average temperatures in the Arctic, some fish species have expanded their habitat ranges from boreal areas to more northern regions and are now found more frequently in the Canadian Arctic. Studies on Arctic seabird and marine mammal diets suggest that invasive fish such as capelin (Mallotus villosus) and sand lance (Ammodytes sp.) are replacing Arctic cod (Boreogadus saida) as the most important prey species in lower Arctic regions (Provencher et al. 2012; Chambellant et al. 2013; Hop and Gjøsæter 2013). Although POPs and mercury are transported to the Arctic, they are still at higher environmental levels closer to the direct sources (e.g. intense agricultural areas, waste incineration). A switch in diet from native to invasive fishes may therefore change ringed seal contaminant burdens. My PhD research will compare contaminant levels in invasive capelin and sand lance to Arctic native fish species, including Arctic cod. I will also determine contaminant levels in ringed seals to better understand how climate change impacts contaminant transfer in Arctic food webs. The results of this project are also important for local communities because, although they do not eat these invasive and native Arctic fishes in particular, locals eat Arctic marine mammals, such as ringed seals that feed on these fishes.

Part of this project includes visiting the local communities in the Arctic that are the most affected by these habitat changes. Arviat, Nunavut is one of the communities collaborating in this project and participated in collecting fish samples. This was my opportunity to visit the Arctic! Last spring, I flew up to Arviat (Figure 1) and gave a few talks regarding preliminary results of my research at the high school, the Arctic College, and the Hunters and Trappers Association.

Figure 1: Town of Arviat, Nunavut (left) in the Eastern Canadian Arctic (right).

My visit in April was short and sweet, consisting of 4 different flights each way… 8 flights in three days (luckily, none of the flights were delayed)! Given the thaw doesn’t happen until June/July in Arviat, late April means snow boots and warm coats. Hudson Bay was a beautiful, expansive white plain (Figure 2)! However, I could tell that it was the spring for them. The locals were walking on the streets, kids were out playing and the roads were clear enough to easily drive through. Everyone looked happy and they were very welcoming. At the high school, I gave a few talks to different classes about my research. The students were interested and engaged, and I even got the wise question “So why does this matter?” from a 12-year-old. Another girl told me that she didn’t like fish and when I asked what she eats instead, she told me about how her father hunts caribou. She invited me to join them on a hunt. If it weren’t for my tight schedule, I would have definitely gone out for a caribou hunt! In this region, they mostly depend on caribou (Rangifer tarandus), seals, and Arctic char (Salvelinus alpinus) for subsistence. High school students will often miss classes and come in tired because the main priority for many of them is to help their families hunt and fish.

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Figure 2: Frozen Hudson Bay in Arviat, NU

After visiting the high school, I went to the Arctic College (Figure 3). Most of the students were gone for the summer but I met a few that stick around and volunteer for research projects. Getting locals involved in environmental research in these remote regions is very important given their sensitivity to climate change and environmental pollution. Fishers and hunters at the Hunters and Trappers Association are concerned about having contaminants in their food, since they depend largely on local food sources. The Arctic Monitoring and Assessment Program (AMAP) has been monitoring contaminants in the Canadian Arctic for over twenty years. The levels of some POPs, such as DDT and PCBs have been declining or have stabilized in the Arctic, mostly since the Stockholm Convention to ban these contaminants (Stockholm Convention 2008). However other contaminants such as mercury have been increasing in some Arctic animals (Riget et al. 2010; McKinney et al. 2015). As a polar environmental scientist, it is my duty to continue researching the impacts of climate change on contaminant levels in these remote regions and to address the communities’ questions and concerns.

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Figure 3: Arctic College, Arviat, NU

Being able to visit one of the most fascinating regions in the world while doing environmental research is why I enjoy being a scientist!

Sara Pedro has a Master’s in Ecology and is currently a PhD student in the Natural Resources and the Environment department of the University of Connecticut, CT.

References:

Borboroglu PG, Boersma PD (2013) Penguins: Natural History and Conservation. University of Washington Press, Seattle

Chambellant M, Stirling I, Ferguson SH (2013) Temporal variation in western Hudson Bay ringed seal (Phoca hispida) diet in relation to environment. Mar Ecol Prog Ser 481:269.

Dietz R, Sonne C, Basu N, et al (2013) What are the toxicological effects of mercury in Arctic biota? Sci Total Environ 443:775–790. doi: 10.1016/j.scitotenv.2012.11.046

Hop H, Gjøsæter H (2013) Polar cod (Boreogadus saida) and capelin (Mallotus villosus) as key species in marine food webs of the Arctic and the Barents Sea. Mar Biol Res 9:878–894.

Letcher RJ, Bustnes JO, Dietz R, et al (2010) Exposure and effects assessment of persistent organohalogen contaminants in arctic wildlife and fish. Sci Total Environ 408:2995–3043. doi: 10.1016/j.scitotenv.2009.10.038

Macdonald RW, Harner T, Fyfe J (2005) Recent climate change in the Arctic and its impact on contaminant pathways and interpretation of temporal trend data. Sci Total Environ 342:5–86. doi: 10.1016/j.scitotenv.2004.12.059

McKinney MA, Pedro S, Dietz R, et al (2015) A review of ecological impacts of global climate change on persistent organic pollutant and mercury pathways and exposures in arctic marine ecosystems. Curr Zool 61:617–628.

Pedro S, Xavier JC, Tavares S, et al (2015) Mercury accumulation in gentoo penguins Pygoscelis papua: spatial, temporal and sexual intraspecific variations. Polar Biol. doi: 10.1007/s00300-015-1697-9

Provencher JF, Gaston  AJ, O’Hara PD, Gilchrist HG (2012) Seabird diet indicates changing Arctic marine communities in eastern Canada. Mar Ecol Prog Ser 454:171–182. doi: 10.3354/meps09299

Riget F, Bignert A, Braune B, et al (2010) Temporal trends of legacy POPs in Arctic biota, an update. Sci Total Environ 408:2874–2884. doi: 10.1016/j.scitotenv.2009.07.036

Screen JA, Simmonds I (2010) The central role of diminishing sea ice in recent Arctic temperature amplification. Nature 464:1334–1337. doi: 10.1038/nature09051

Stockholm Convention (2008) Listing of POPs in the Stockholm Convention. http://chm.pops.int/TheConvention/ThePOPs/ListingofPOPs/tabid/2509/Default.aspx. Accessed 28 May 2015

Human Exposure to Pharmaceuticals via Vegetables: Current Research and Future Directions

By Sara Nason

Like many scientists, I often find myself explaining my research to my friends and family.  However, I am usually hesitant to launch into a full explanation of my projects, as most people are not as interested in the mechanisms of how plants take up pharmaceuticals as I am. As soon as I start describing my research, all sorts of questions come up – most of which are not directly related to my work.

When deciding on a topic to write about for the SETAC student blog, I considered focusing on the research that I work on every day.  However, I would probably digress into a detailed description using lots of scientific jargon, and my blog entry would not be very exciting.  Instead, this post is about an issue that often comes up when I discuss my research with someone outside of my field – human exposure to pharmaceuticals that have been taken up by crop plants.  Specifically, I focus here on a recent paper in Environmental Science and Technology by Ora Paltiel and others: Human exposure to wastewater-derived pharmaceuticals in fresh produce: A randomized controlled trial focusing on carbamazepine.1

Scientists working at the Hebrew University of Jerusalem recently detected carbamazepine, an anti-epileptic drug, in the urine of people eating vegetables that were irrigated with treated wastewater.  This is the first study to demonstrate that pharmaceutical contamination in irrigation water results in human exposure to pharmaceuticals via consumption of irrigated crops.

Researchers provided study participants with a box of vegetables to consume over the course of a week. Some participants received vegetables grown with freshwater irrigation, while others received vegetables grown using treated wastewater irrigation. New boxes were provided the following week that only contained vegetables irrigated with freshwater.  The scientists collected urine samples from the participants throughout the two weeks, and found that urine concentrations of carbamazepine increased during the first week for participants eating the treated wastewater vegetables, but not for the freshwater group.  Carbamazepine levels returned to baseline levels by the end of the second week.

Irrigation using treated wastewater is a surprisingly common practice worldwide, especially in arid locations.  In California, where most of the produce in the United States is grown, nearly half of treated wastewater is used for agriculture, and in Israel, more than 70% of treated wastewater is used directly for irrigating crops.2 Pharmaceuticals enter the wastewater treatment system because humans and animals do not fully break down most drugs and a significant portion is excreted in urine. Even in fully industrialized nations, most wastewater treatment does not fully remove pharmaceuticals, so the chemicals go wherever the treated wastewater goes – into lakes, rivers, and streams, or directly onto crop plants.

Plant uptake of pharmaceuticals became a topic of concern starting about 10 years ago, after several studies found pharmaceuticals in run-off water from crop fields.  The first few years of research focused largely on proof-of-concept experiments – tests where plants were grown in labs and greenhouses and exposed to higher concentrations of pharmaceuticals than are typically found in the environment.  These studies showed that plants can take up many types of pharmaceuticals.  More recent studies have investigated exposures to lower concentrations of pharmaceuticals using plants grown in more realistic scenarios, showing that the potential for plants to take up pharmaceuticals in standard agricultural systems clearly exists.3

The big question that is still up for debate is whether or not human exposure to pharmaceuticals via consumption of contaminated crops might have impacts on human health. Within the big question, there are two smaller questions that are the focus of current research.

PPCPFlowchart
Figure 1: A recent publication demonstrates that people can be exposed to pharmaceuticals by eating vegetables that were irrigated with treated wastewater. Continuing research focuses on understanding the exposure pathway well enough to predict any potential health impacts.

First, we need to know more about the effects low concentrations of pharmaceuticals may have on human health – at what amount (in plants) will pharmaceuticals begin to have an effect on people?  Pharmaceuticals in the environment are usually present as mixtures, so although the concentration of each one may not be close to a normal therapeutic dose, there could be unexpected effects from drug mixtures and interactions.  While scientists are currently researching the effects of very low doses of pharmaceutical mixtures, much of the research that has been done so far has focused on model organisms for aquatic ecosystems, such as water fleas, zebra fish, and minnows, rather than on plants and humans. Most human risk assessment so far has used estimates of toxicity based on the molecular structure of pharmaceuticals and not on experimental data.

Second, we need to have a better understanding of how much of different pharmaceuticals is being taken up by crop plants in the field – enough to meet the threshold for effects on humans? While more than 100 pharmaceuticals have been studied in plant uptake experiments,3 thousands more are currently in use, with new drugs constantly being developed.  Testing all produce samples for the presence of pharmaceuticals is highly impractical, so accurate predictions of plant uptake are necessary. Some scientists have attempted to use models to predict plant uptake, but there are still large gaps in our understanding of the biological and chemical processes involved.

My research focuses on these knowledge gaps – I look at variables such as soil pH, nutrient availability, and toxicity of pharmaceuticals to plants – factors that may affect how much of a pharmaceutical can enter and accumulate in a plant. I work with model organisms and do a lot of method development – things that don’t feel relevant to the outside world by themselves. Reading articles like the one described above and thinking about the larger questions connected to my research makes me feel like a part of the greater scientific community and like I am doing something of significance for the world.  I think that is one of the great things about being in the environmental toxicology and chemistry field.  It will be exciting to see where the science goes next!

Sara Nason is a PhD student in Environmental Chemistry and Technology at the University of Wisconsin-Madison

References:

(1)        Paltiel, O.; Fedorova, G.; Tadmor, G.; Kleinstern, G.; Maor, Y.; Chefetz, B. Human exposure to wastewater-derived pharmaceuticals in fresh produce: A randomized controlled trial focusing on carbamazepine. Environ. Sci. Technol. 2016, acs.est.5b06256.

(2)        Sato, T.; Qadir, M.; Yamamoto, S.; Endo, T.; Zahoor, A. Global, regional, and country level need for data on wastewater generation, treatment, and use. Agric. Water Manag. 2013, 130, 1–13.

(3)        Miller, E. L.; Nason, S. L.; Karthikeyan, K.; Pedersen, J. A. Root Uptake of Pharmaceutical and Personal Care Product Ingredients. Environ. Sci. Technol. 2015, acs.est.5b01546.