WER & Biotic Ligand Model Testing


EnviroScience biologists have extensive experience with culturing and examining many different species of freshwater, saltwater, and sediment organisms. Our toxicologists can customize study plans to meet numerous requirements for specialty projects meeting the needs of each individual client. Contact our Bioassay Laboratory using the form below or call 800.940.4025 to find out how EnviroScience can tailor a special toxicity test to meet your unique needs.

Water Effect Ratio (WER)

EnviroScience’s Bioassay Laboratory performs Water Effect Ratio (WER) evaluations. WER evaluations may be used to derive site-specific limits for certain metals from national and state aquatic life criteria that were originally developed using laboratory toxicity data.

The U.S. Environmental Protection Agency (USEPA) established federal guidelines to derive site-specific criteria for certain metals including arsenic, cadmium, chromium (III), chromium (VI), copper, lead, mercury, nickel, selenium, silver, and zinc. A number of physical and chemical characteristics of site water and metal can affect the toxicity of that metal to aquatic organisms in particular surface water. When deriving site-specific aquatic life criteria for a metal, the difference between the toxicity of the metal in laboratory water and site water may be adjusted with a site-water effect ratio.

Toxicity differences between site water and synthetic laboratory water are compared in the laboratory and evaluated for differential lethal concentrations. The toxicity endpoints from these two tests are used to calculate the WER, which is then multiplied by the national or state aquatic life criterion to calculate the site-specific limit.

Biotic Ligand Model

The Biotic Ligand Model (BLM) is a tool that predicts the toxicity of metals in specific environments. It is currently accepted for usage in determining environmentally protective levels of copper by the USEPA and several state agencies. The model provides an estimate of the relative toxicity of copper based on the specific site water chemistry. Models are currently in development for other metals such as aluminum, nickel, and zinc.

The traditional hardness-based criteria generate a range of protective values but do not consider some of the most important factors that affect metal bioavailability. The BLM goes further and calculates metal toxicity to aquatic organisms as a function of simultaneous concentrations of additional chemical parameters in the water. For example, other ions can either complex with copper and render it biologically unavailable, or they may compete with copper for binding sites at the point of entry into a vulnerable organism. The addition of these ions may reduce the overall toxicity of the copper in the water. 

Our Services

EnviroScience provides high-quality environmental services to hundreds of satisfied municipal, industrial, and private sector clients throughout the Midwest and Northeast. We have clients in Ohio, Pennsylvania, West Virginia, Illinois, New York, Michigan, Indiana, Tennessee, and many other states. EnviroScience has an excellent reputation with regulatory agencies on both the state and federal levels. Our confidence in our methodology and the professionalism of our experienced biologists allow us to guarantee that our procedures and reported data will meet all acceptance criteria.

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    Few environmental firms in the country retain EnviroScience’s degree of scientific know-how, talent, and capability under one roof. The diverse backgrounds of our biologists, environmental engineers, scientists, and divers enable us to provide comprehensive in-house services and an integrated approach to solving environmental challenges—saving clients time, reducing costs, and ensuring high-quality results.

    Our client guarantee is to provide “Excellence in Any Environment,” meaning no matter what we do, we will deliver on our Core Values of respect, client advocacy, quality work, accountability, teamwork, and safety. EnviroScience was created with the concept that we could solve complex problems by empowering great people. This concept still holds true today as our scientists explore the latest environmental legislation and regulations and incorporate the most up-to-date technology to gather and report data.

    EnviroScience expertise includes but is not limited to aquatic surveys (including macroinvertebrate surveys and biological assessments); ecological restoration; ecological services (including impact assessments, invasive species control, and water quality monitoring); emergency response; engineering and compliance services; endangered mussel surveys; laboratory and analysis; stormwater management; threatened and endangered species; and wetlands and streams (including delineation and mitigation). Further, EnviroScience is one of the few biological firms in the country that is a general member of the Association of Diving Contractors International (ADCI) and offers full-service commercial diving services.