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Delicate pollinator-plant relationships: Forged through coevolution and critical considerations for risk assessment

Posted on June 7, 2021

Pollinator-plant relationships represent some of the most striking examples of mutualism and coevolution in all of nature. We’ve discussed in our pollinator protection article how native bees can be generalists, often thriving on a diverse availability of flowering plants. This diversity is a benefit to both bee and plant alike. From a bee’s perspective, diverse food sources can supply a well-rounded diet and from a plant’s perspective, diversity in pollinators helps to assure successful reproduction. However, these symbiotic interactions can be driven by specific pollinator preferences, sometimes to the point of becoming a completely obligate relationship.

Plants are pollinated by different types of animals, the most common of which include bees, flies, butterflies, beetles, moths, bats, and birds. Each of these animal pollinators displays specific preferences, such as color, scent, flower shape, presence or absence of nectar guides, and characteristics of nectar and pollen. For example, without a sense of smell, birds are attracted to bright red or orange flowers. In return, plants relying on avian pollination have evolved to be typically odorless, bright in color, with funnel or cup-shaped flowers and sometimes a strong base for perching. Plants that have evolved for pollination by bats or moths emit scents at night to account for nocturnal activity patterns: musty scents for bats and strong sweet scents for moths. (Next time you’re admiring a beautiful flower, challenge yourself to consider what traits may have evolved in response to pollinator preferences! Information from the U.S. Forest Service provides some great details to get you started.) 

Green-crowned brilliant hummingbird (Heliodoxa jacula) feeding on nectar from bright, funnel-shaped flowers

Evolutionary pressure can also yield extreme examples of pollinator-plant relationships, some of which represent complete species-to-species dependence. For example, the death camas (Anticlea elegans) is a beautiful flowering plant that is deathly toxic to most pollinators and animals. Yet even this plant has developed a single pollinator relationship with the solitary andrenid bee (Andrena astragali). Curiously, the adult andrenid bee is also unable to consume the pollen or nectar of the death camas, but its kids love it! Once hatched, the bee larva consumes the pollen ball. It is not completely understood if the larvae are immune to the plant toxins or if the toxic chemicals degrade prior to consumption.

The deceptively beautiful white flowers of the highly poisonous meadow death camas (Zigadenus venenosus)

The intricate relationships between pollinators and plants has become a focal point for toxicological consideration in Endangered Species Assessments for US EPA. During these assessments, we conduct a three-step consultation process to evaluate the potential risk to Federally-listed threatened or endangered species. While direct effects of chemicals are characterized, we also examine indirect effects during Step 1 of an Endangered Species Assessment (ESA). Indirect effects refers to impacts on other species for prey, habitat, or symbiotic interactions upon which a listed species relies and is the last step in the decision tree for Step 1 of the ESA. For example, a chemical may not be directly toxic to an endangered pollinator, but an indirect effect could occur if the chemical affects the plant(s) that the pollinator relies upon for a food source. It is the last step in the decision tree for Step 1 of the ESA. Up until this point, an individual species has not been determined as a “no effect” species. In the case of “indirect effects”, a species may have an obligate or a generalist relationship to another species that is directly affected by the chemical being assessed. An obligate relationship infers that one or both of the listed species depends on the other for its survival. A generalist relationship means that a species is able to survive on a variety of other species and is not solely dependent on one for survival.

An example is the endangered species, Dicerandra immaculata (Lakela’s mint), a small fragrant shrub. This species occurs in six isolated sites in the southern Indian River and northern St. Lucie counties in Florida. Lakela’s mint has a generalist relationship, relying solely on pollinating insects for survival. Another example is the Karner blue butterfly (Lycaeides Melissa samuelis), an endangered species located mainly in Wisconsin but also found in Indiana, Michigan, Minnesota, New Hampshire, New York, and Ohio. This species has an obligate relationship to the wild lupine (Lupis perennis) because the butterfly’s caterpillars only feeds on wild lupine leaves, making this species dependent on the wild lupine for its survival.

Understanding the precise species interactions is critical for an in-depth look at potential exposure and risk of a chemical to a listed species. The beautifully intricate pollinator-plant relationships, which are the result of millions of years of coevolution, serve as a prime example of these interactions!

Karner Blue Butterfly (Polyommatus icarus)


Recent and Upcoming Highlights from our Pollinator Protection Work

Posted on June 7, 2021

Much of the most recent research in pollinator protection, and in fact a lot of new ecological research in general, is focused on computer model simulations, such as the BEEHAVE model. In particular, recent honeybee-specific projects have incorporated BEEHAVE to simulate the development of a honeybee colony and its nectar and pollen foraging behavior in different landscapes. BEEHAVE additionally allows for representation of multiple stressors to honeybee colonies and predicts the potential impact on colony development and survival.

Our Effects Team has used the BEEHAVE model for various projects and found it invaluable in honeybee colony predications. For example, in collaboration with the Pollinator Research Task Force, we recently released a 2-part publication series in Environmental Toxicology & Chemistry presenting, 1) a model validation of BEEHAVE using large-scale colony feeding studies, which can be used to inform the use of BEEHAVE to higher-tier ecological risk assessments, and 2) an application of BEEHAVE to analyze overwintering outcomes from simulated large-scale colony feeding studies. The findings from this work can be used to inform study designs for a large-scale colony feeding study in order to improve overwintering success in control hives and drive consistency within and across studies.

BEEHAVE was a star at May’s 2021 SETAC Europe conference where a new mechanistic effect model (BEEHAVE-Ecotox) was demonstrated to link realistic exposures of bees in the field with subsequent effects on different levels of the colony. We’re excited to review this work once published, as this model has significant risk assessment implications, including the capacity to extrapolate from laboratory to semi-field and field studies as well as the option to study effects in different crops and regions and to test various mitigation strategies.

Beyond BEEHAVE…  Waterborne’s scientists will soon be presenting and publishing a slew of recent work in the field of pollinator protection, including:

Keep an eye on our upcoming newsletters for more details on our recent pollinator work.

Also, Waterborne’s Lead Ecotoxicologist, Jenn Collins will be co-chairing and presenting during the upcoming pollinator session of the American Chemical Society National Meeting in August. Other co-chairs for this session include environmental scientist John Purdy, Tom Steeger and Katrina White from the US EPA, and Annie Krueger from the University of Nebraska-Lincoln. This session is gearing up to be full of great presentations and new considerations for pollinator risk assessment.


Let’s bee informed about honey bee foraging

Posted on June 7, 2021

There is something mesmerizing about watching bees at work! These little workers have been agriculturally critical to humans for thousands of years, and over this extended time, we have accumulated a wealth of research about their physiology and behavior. Here, we focus on honey bee foraging behavior, which provides us with a fascinating example of how the honey bee colony functions more as a superorganism than a population of individuals.

Honey bee foragers collect all of the nutritional elements for their colony, including nectar, pollen, and water. Water is sourced close to the colony and used to hydrate and cool the colony during hot weather. Research has shown that pollen foraging, a colony’s main source of protein, minerals, and vitamins, is directed by the colony’s current state. Pollen stores are vital for brood production and healthy development of young within the hive, and pollen foraging has been shown to be regulated by the presence of brood pheromone and young larvae in the colony, as well as the quantity of stored pollen. Nectar, on the other hand, is the primary source of carbohydrates and provides the necessary energy for foragers and the colony as a whole. Honey bees store nectar as honey and securing healthy supplies allows for strong colony maintenance and overwintering.

Contrary to pollen foraging, bees continue to forage for nectar regardless of the honey stores in the colony. However, plans in the colony are subject to change! Larval pheromones have been shown to transition the behavior of nectar-foraging bees to pollen foraging for a duration of time to meet a growing need of pollen in the colony.

It is also important to note that not all nectar and pollen sources are equivalent. Just as flowers physically differ, flowers provide varying types and levels of nutritional elements. Forager bees will often visit a buffet of different flower types to bring well-rounded sustainment back to the colony. Interestingly, bees base foraging decisions on the nutritional value of certain flowers and their own colony’s requirements.

Foraging preference studies have demonstrated that the highest criteria for foraging was nutritional content of protein and relative availability of resources, especially when the colony need was high (indicated by number of larvae). In one study, white clover (Trifolium repens) and then daisy fleabanes (Erigeron annus) were visited most frequently and accounted for the most collected pollen when colonies were given a diverse landscape of floral resources. The same study showed observations of peak foraging rates in the early afternoon and that foraging was highly dependent on temperature outside the hives. The high energy demand for flight muscle movements means that honey bees very rarely forage below 55 °F (13 °C) or above 100 °F (38 °C).

Honey bees are experts at efficiency determination, measuring their own spent energy to required work ratios in real time and relaying the best foraging locations to the colony on their return. They do this through the “waggle dance,” which is exactly what it sounds like! When worker bees return from optimal locations, they wiggle their bodies in a way that the other bees understand as both directions and distance to the best foraging location. What looks like an adorable dance is in reality a very precise method of communication. Angles and duration of these “dances” relay the direction and distance. Bees are showing us that dancing isnt’ just for after-work fun…it IS work!

While there are many factors that impact honey bee foraging behavior, it’s clear to see that honey bees are never blindly working. It’s been several centuries since Chaucer introduced the saying “busy as a bee,“ but, given all we know about bees, we should take this idiom on face value. Bees pursue directed work with decision-based efficiency rather than aimlessly buzzing around.


There are so many more bees beyond honey bees: It’s time to show our native bees some love!

Posted on June 7, 2021

Did you know that there are over 20,000 recognized species of bees around the world, 4,000 of which are native to the United States? Although pollinator protection efforts have been a core focus in ecological stewardship, most of us tend to focus on the European honey bee (Apis mellifera) and miss out on the bulk of the wonderfully diverse pollinator populations found across the globe.

The European honey bee has long been used as the surrogate species for both Apis and non-Apis bees and other insect pollinators in risk assessments. The focus on A. mellifera makes sense for a few reasons: (1) we have a strong understanding of its behavior and ecology, (2) A. mellifera have a long history of management for honey production and, more recently, crop pollination, and (3) this species is commercially available and relatively easy to keep under laboratory conditions.

Focusing on the European honey bee has its drawbacks. For example, the protection goals set forth in the 2014 Guidance for Assessing Pesticide Risk to Bees by the USEPA, Health Canada and the California Department of Pesticide Regulation, including maintenance of pollination services, hive production, and biodiversity, do not uniformly apply to both Apis and non-Apis bees. In other words, thousands of non-Apis bee species may not benefit from protective efforts set forth by these guidelines and could be at a potential risk from pesticides. Bee species are diverse in life cycle, sociality, nesting and foraging behavior, overwintering, and size and their diverse ecology and behavior should be accounted for when considering risk from chemical exposure and toxic effects.

While the European honey bee receives most of the credit, many species are very important for crop pollination—and few of them are managed for this purpose. In many cases, non-Apis bees turn out to be more effective pollinators than the honey bee, such as:

Bumble Bees

Bumble bees (Bombus ssp.) are relatively large in size as well as furry in comparison to many other bees, allowing them to pick up and carry more pollen from plant to plant. They are social bees, but with only a few hundred worker bees, their colonies are much smaller than European honey bee colonies. Bumble bee colonies do not overwinter. Instead, mated queens overwinter and start a new colony on their own in the spring. Bumble bee species are commercially available for crop pollination in North America, Europe, and Asia.

Solitary Bees

Not all bees live in colonies! Solitary bees comprise a vast variety of bee species that, in turn, employ various nesting strategies. A few of these solitary bee species can be managed for crop pollination, most prominently species in the genus Osmia: blue orchard bees and the red mason bees are used in orchard pollination, and the leaf-cutting bee, Megachile rotundata, is managed for alfalfa pollination. These three species nest in above-ground, existing cavities, making it relatively easy to provide artificial nesting sites and collect the overwintering bees that have not emerged from their cocoons yet.

However, the majority of bee species nest underground, usually digging their own nests. Examples include the following bees: the squash bee (Eucera pruinosa) which exclusively forages for the pollen of plants in the cucurbit family and the alkalibee (Nomia melanderi), an avid pollinator of alfalfa. The alkali bee is found in the Western United States and nests in soils with high salt content. It can form large nest aggregations in suitable locations and farmers may set aside and manage areas close to their alfalfa fields to create the right nesting conditions for the bees.

In tropical regions, including for instance Brazil, stingless bees (Meliponini) are considered key pollinators. Like the honey bee, they are highly social and live in large colonies. They comprise a variety of species across the globe with a large diversity in ecology, nest architecture, and substrates used for nest building.

Chemical Impact

In order to consider the potential impacts of chemicals to the wide variety of bees, we must acknowledge the different routes of exposure. Dependent on the species and its ecology, bees can come into direct contact with chemicals through dust or spray, mud and soil, nesting materials (e.g., wax or leaf pieces), plant surfaces and plant resins. In addition, bees can also be exposed orally to residues in nectar and pollen. Exposure will also vary depending on life-stage and, in social bees, castes. Beyond the exposure routes, bee physiology can result in different sensitivities to toxic compounds across bee species.  As you can see, bees can vary greatly in biological and behavioral characteristics and research is needed to better understand the interaction between these characteristics and the potential pesticide exposure and effects at the level of a colony or population. Recently, we have been working to apply a trait-based vulnerability assessment across 10 different bee species with individual and population-level implications. We’re looking forward to publishing our findings soon. Stay tuned to our upcoming newsletters for more on this important work. In the meantime, we encourage you to explore the various bee species native to your area. The Xerces Society has a multitude of educational resources if you’d like to learn more about the diverse pollinators in your region.


Protecting pollinators in your own backyard

Posted on June 7, 2021

Pollinator protection has long been a significant initiative for agriculture and environmentalists, making the recent threat of diminishing pollinator populations cause for increased concern. Fortunately, as we have learned from society’s response to other environmental concerns like water pollution, when an environmental issue becomes a hot topic in the general population, significant action takes place. With excitement comes a rush of activity; it can be difficult to interpret all the information coming at us at once, weed out the misinformation, and determine what we can do on an individual level to have an impact on pollinator health.

The good news is that every individual, business, farm, and community can work to encourage pollinator health in our backyards and communities. Resources abound and one of the best is the Xerces Society, an organization dedicated to protecting invertebrates, including pollinators. Its website is a tremendous source of information through a plethora of articles, lists, and links to pollinator health information. Xerces makes it easy to zoom in on your location for local information through their map function.

The core principles for encouraging native bees and other pollinators all focus on making appealing, diverse, and nutritional plant life accessible. To achieve this in your space, consider the following:

Not all of us have control over our lawns and yards, but now that we understand the basics, we can start to educate others and promote pollinator protection within our own communities. Why not ask the landlord of your home or office about making small changes with specific recommendations?

Obviously, many of us do not want our yards to become their most natural selves…that’s fine! If you can spare a small area within your yard or garden to convert to natural state with natives thriving, that’s a great start! No one person can save the entirety of the bee population. But if we do what we can to provide little pockets of protective habitat, then we are doing our part to help our native pollinator populations blossom (pun intended).


Applying Our Environmental Modeling Tools in the Fight Against COVID-19

Posted on May 10, 2021

There is no doubt that the ongoing COVID-19 pandemic has impacted all of us, to varying degrees, either directly or indirectly. While 2020 will live on in history as a year of epidemiological and economic devastation, a silver lining can be found in how the pandemic has shaped the course of scientific research: insights and collaboration within the scientific community progressed on a global scale at a pace we have never quite seen before. It did not take long for us to realize that our tools and expertise in environmental modeling could play a role in the arms race between the SARS-CoV-2 virus and scientific research.

Waterborne’s Raghu Vamshi and Scott Dyer, in collaboration with the American Cleaning Institute, LeTourneau University, and the University of Arkansas, have been working to analyze the fate and transport of SARS-CoV-2 in U.S. wastewater and surface waters using iSTREEM®.  This is a novel application of iSTREEM®, which is a public, web-based and spatial model designed to estimate concentrations of down-the-drain materials in wastewater effluent, receiving waters, and drinking water.

It seemed like everyone and everything was asked to pivot during the pandemic, and iSTREEM® was no different; the application of this fate and transport model was investigated as a new tool for COVID-19 tracking efforts. Since the viral RNA is excreted from infected individuals, wastewater-based epidemiology can provide valuable insights into upstream positive caseloads considering the physical and economic challenges of clinical testing for viral infection. iSTREEM® was deemed a suitable application for this research due to its up-to-date waterway connection to the U.S. population, wastewater treatment infrastructure, and river network. 

One way that iSTREEM® was used in COVID-19 detection was to estimate wastewater and surface water concentrations of the virus for the continental U.S. The monitoring data (i.e., viral loads taken from highly significant regressions of measured influent concentrations from numerous Ohio wastewater treatment plants (WWTPs)) was paired with 10-day cumulative positive COVID-19 caseloads for inputs into the model. Removal of SARS-CoV-2 via WWTPs was determined and estimated from recent studies conducted by the University of Arkansas and augmented from literature search, which also considered surrogate viruses and organic chemicals. First-order decay rates were based on loss rates of various viruses in surface waters and expert knowledge of highly biodegradable materials. All this information was used for iSTREEM® modeling of the continental U.S. over multiple temporal scales during the course of the pandemic. The analysis of results at the national scale clearly indicated that WWTPs are highly efficient in removing SARS-CoV-2.

Fortunately, this research showed that residual RNA fragments that remained in wastewater effluent were diluted in the surface waters, resulting in concentrations below current detection limits. It can be expected that treatment of drinking water will result in even greater loss of viral fragments leading to a highly confident assessment that SARS-CoV-2 does not pose a health risk to the population in the U.S. via drinking water.  This is the first study to provide quantitative data at a national scale to support these claims. Stay tuned to our future newsletter for release of the publication describing this project!

The incorporation of wastewater data in epidemiology may not be a brand new concept, but the COVID-19 pandemic is certainly solidifying wastewater epidemiology as critical tool. In fact, The University of California Center for Information Technology Research in the Interest of Society (CITRIS) and researchers of UC Merced have developed a global dashboard for SARS-CoV-2 wastewater monitoring efforts. The aptly named “COVID19Poops Dashboard” enables global collaboration in the wastewater epidemiology efforts being used in the fight against COVID-19. Check out the dashboard and see what monitoring efforts are taking place near you!


Filling a Global Data Need for Surface Runoff and River Flow Data

Posted on May 10, 2021

The availability of detailed surface runoff and river flow data across large geographic areas is crucial for diverse applications.  Only a few countries have such data at a high resolution (HR).  Paucity of detailed input spatial data and challenges with intense processing were the limiting factors in developing HR surface runoff and river flow datasets over large spatial scales.  USDA’s well-established Curve Number (CN) method was applied as a spatially distributed hydrologic modeling approach to estimate surface runoff.  HR global datasets for hydrologic soil groups, land cover, and precipitation were spatially processed by applying the CN equations to create a contiguous global mean annual surface runoff grid at a HR of approximately 50 meters.  Surface runoff was spatially combined with detailed global hydrology of catchments and rivers from HydroBASINS and HydroRIVERS to estimate mean annual flows across the global river network, which includes about 1 million river segments covering the globe.  Estimated river flows were compared with measured gauge flows across several countries showing good correlation between estimated and measured flows.  The river flows will be made publicly available and can be extracted for use over large regions or small watersheds across the globe.

Stay tuned to our future newsletter for release of the global river flow data and publication describing this complex dataset’s creation!


Waterborne Investigates Environmental Stressors to Coral in the Florida Keys

Posted on May 10, 2021

One of the most diverse ecosystems in the world are the coral reefs.  Corals can grow in both shallow and deep waters but corals that build reefs are generally found in shallow subtropical and tropical waters.  Known as the “big cities in the sea”, coral reefs are home to thousands of species.  Since these ecosystems are pertinent to the survival of several thousand species, the decline of corals is a global concern. Recently, Waterborne scientists and engineers, in collaboration with the Consumer Healthcare Products Association, investigated specific stressor impact on the widespread decline of coral in the Florida Reef Tract.

Coral reefs are threatened by multiple stressors, most notably by the global sea temperature change and acidification due to the rise in atmospheric CO2 levels.  Stony Coral Tissue Loss Diseases (SCTLD) are of particular concern for coral health and is important to consider in a multi-stressor assessment. On a local scale, stressors can include invasive species, unsustainable fishing practices, and tourism-related damage.  Recently, a few scientists have hypothesized the potential for certain sunscreen active ingredients to be a significant contributor to the decline in coral health. Conservation efforts are built on investigating such stressor impact hypotheses.

We focused our evaluation on environmental stressors to Florida Reef Tract coral in the Florida Keys through the lens of accepted global and local factors. We considered the following environmental stressors, in order of magnitude: sea surface temperature, SCTLD, land-based pollutants, marine-based influences, and sunscreen active ingredients.

The active ingredients oxybenzone and octinoxate in sunscreens have been effective in UV filtering for 40 years, reducing the amount of melanoma cases by 50% for sunscreen users. This certainly indicates a human health benefit for the use of UV-filter sunscreen products. That said, it is important to consider if continued use of these products impacts the health of coral reef ecosystems. To this end, we incorporated a systematic literature review of coral reef stress factors and coral reef impact assessments, an investigation of monitoring results of sunscreen active ingredients in marine and coastal waters, and a screening evaluation of local anthropogenic factors in Key West in context with proximity to coral and associated bathymetry and ocean currents. These elements were used to assign a relative ranking of factors contributing to degradation of coral in the waters around Key West and develop recommendations for next steps for the protection of reef resources in Florida waters.

Preliminary laboratory studies have been conducted on oxybenzone and octinoxate in an attempt to characterize toxic effects. These studies were short in duration (≤ 7 days) exposing various types of coral (e.g., Acropora pulchra, Stylophora pistillata, Pocillorpa domiconis) to different concentrations of oxybenzoate and/or octinoxate. Further long-term testing is needed in order to assess any chronic effects. These short-term studies also lacked robust testing methods to define measured concentrations of the UV-filters in water and the results have not been reproduced by other researchers.  Based on these preliminary peer-reviewed studies, toxic effects of oxybenzone and octinoxate could not be demonstrated. Therefore, UV filters have not been shown to directly damage Atlantic coral reef populations or decrease their ability to respond to other environmental stressors.

Monitoring of these active ingredients has not been conducted in the Florida Keys; however monitoring efforts from populated beaches such as the Virgin Islands and Waikiki, HI have resulted in UV-filter concentrations either in the parts-per-trillion range or below levels of detection. It is important to consider that even the detections in the parts-per-trillion range from populated beaches are representative of shoreline, publicly-accessible locations. Corals in the Florida Keys are located miles away from the shoreline, indicating that concentrations near corals would be much lower.

Although further research is needed to successfully characterize chemical toxicity effects on coral species, weight-of-evidence assessments have not identified UV-filter active ingredients from sunscreens as a contributor to coral decline. These stressor impact evaluations play a critical role in improving and targeting mitigation and conservation efforts. Although our assessment indicated these active ingredients are likely not significant stressors to coral, we are able to recommend that conservation efforts be focused on known significant stressors including recreational practices in and around the coral reef to reduce the spread of SCTLD and minimize structural damage to the reefs. Read more about this work at https://www.chpa.org/sites/default/files/media/docs/2021-03/Environmental-Stressors-to-Coral-in-the-Florida-Keys-11182020.pdf.


Modern Wastewater Treatment: The Marvel of Civil Engineering We Take for Granted?

Posted on May 10, 2021

“But…where does it go?” It’s a question we might hear from a toddler while potty training or seeing something rinsed down the drain. We rarely think about it in our daily lives, yet wastewater treatment plants (WWTPs) remain a crucial part of the modern human impact cycle, with a direct impact on ecological and human health, as well as climate change. At the start and end of our plumbing system, WWTPs represent a marvel of civil engineering firmly set to protect harmful impacts of the water to humans and ecology, as well as the harmful impacts of humans to the water.

Anything you buy that ends up in the sewer can be considered a down-the-drain product: shampoo, mouth wash, sunscreen, medicine, drain cleaner, even particles that wash off your clothes. If it goes down the shower, sink, toilet or washing machine within a US municipal district, it will end up at a WWTP.

At the WWTP, primary treatment involves removal of pollutants and contaminants through screening and settling out of large particles. Organic matter is then removed via microbial degradation during secondary treatment, with a disinfection step (e.g., chlorination) to remove the bacteria following degradation. Some communities also incorporate an advanced treatment process for removal of special concern pollutants, such as nitrogen or phosphorus. After treatment, the treated water is then released into local waterways, where it can be used again for any number of purposes, such as drinking water supply, crop irrigation, and sustaining aquatic life.

WWTPs must continually evolve, making sure their infrastructure is suitable for the populations served while integrating modern research for treatment of emerging contaminants. For example, research has shown that the presence of both antibiotics from hospital, veterinary, or local drains and pathogens that accompany waste is a continual driver of bacterial evolution and contributes to antibiotic resistance. Examples such as these make it clear that investment in improved, state-of-the-art WWTPs is an investment in our health, the environment, and our future.

What can we do to help?

Begin by understanding that that what goes down-the-drain has the potential to, quite literally, live on. This knowledge check will hopefully urge us to make mindful changes around our homes.

Earth911.com is a great resource for searching your local recycling programs and hazardous waste disposal days by entering your zip code. You can also take an active role in understanding your local WWTP network, or learn more about how WWTPs function (https://www.youtube.com/watch?v=FvPakzqM3h8). You’ll be armed with a stronger answer the next time a child asks, “but…where does it go?”


Down-the-Drain Products and iSTREEM®: A Game-Changer in Evaluating Risk

Posted on May 10, 2021

While ecological risk assessment has focused on priority contaminants such as pesticides for decades, scientists and regulators around the world have had an increasing focus on the environmental impact of everyday chemicals found in home and personal care products and pharmaceuticals. These materials, along with a few others used indoors, constitute down-the-drain products.

Most of us probably don’t put much thought into our own, continuous contributions to down-the-drain materials. As a quick exercise, I made a list of my down-the-drain contributions just from this morning. First, hygiene products: toothpaste, mouthwash, shampoo, soap, conditioner, body lotion, deodorant, some plethora of skincare products, makeup, and hair products…then my daily vitamins and medication. I had a few extra minutes for chores this morning, so I needed to add dish soap, laundry detergent, and fabric softener. But wait, there’s more! Clothing in the washing machine can also contribute to down-the-drain exposure through the breakdown of synthetic fibers into nanoparticles and microplastics…so I need to add that to my list. That’s a pretty long list for an hour morning routine and it drives home an important point: most of what we use in our homes ends up going down-the-drain where, for those of us in cities, it is eventually transported to a municipal wastewater treatment plant (WWTP).   

After treatment, the effluent from WWTPs feeds into surface water bodies. Thankfully, we have tools like iSTREEM® to help us model the fate of these down-the-drain materials to ensure safety in our surface and drinking water. iSTREEM® is a publicly-available, web-based, spatially explicit model that estimates the concentration of a chemical that goes down-the-drain and the residual levels that subsequently enter the aquatic environment. Providing predicted environmental concentrations in effluent, receiving waters, and drinking water intakes, iSTREEM® is a critical tool beyond screening-level and used in higher-tier risk assessment of down-the-drain products.

iSTREEM® was originally developed decades ago by Procter & Gamble. Over the past 10 years, through a collaboration with the American Cleaning Institute, and Waterborne has been at the helm of the model’s development, testing, expansion, and outreach. In fact, iSTREEM® was named as one of the 20 most innovative and influential tools in 2013.

Waterborne’s iSTREEM® work, led by Raghu Vamshi, involves continuous evolution of the model and its application. Beyond its utility as an exposure assessment tool for conventional down-the-drain products in the U.S., we have employed modifications of iSTREEM® to investigate microplastics, veterinary medicines, pharmaceuticals, and artificial sweeteners. In addition, we actively engage in outreach activities of the model to encourage and support the user community.

In collaboration with Proctor & Gamble and American Cleaning Institute, we have officially expanded the iSTREEM® framework into a global model to cover China, Japan, Canada, Mexico, and more. This expansion was made possible by modern improvements in technology and computing power which allows us to efficiently integrate high-resolution datasets at a global scale. The current evolutionary step for iSTREEM® allows it application for exposure assessments of down-the-drain products not just in the U.S., but across the globe.

Visit istreem.org for the latest on iSTREEM® and stay tuned to our future newsletter for release of the publication describing iSTREEM global expansion and outreach activities!

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