The Toxicity Test Guide

By Andrea Cohen, Tests.com Contributing Writer

Environmental toxicology is the determination of the toxicity of chemicals found in the environment. Each year, over four billion pounds of toxic chemicals are released into the nation’s environment. While one might assume that the government or major regulatory organizations would know which chemicals are toxic to the environment, the truth is that, for the most part, information about toxicity of various chemicals in the United States is just not known or is not made available. It is important to determine whether chemicals or other substances used by industry or in or around home and business environments have the potential to cause damage to the environment or human health.

Studies performed by the United States Environmental Protection Agency (EPA) have found that most chemicals used commercially do not have documented basic toxicity data available. While we may not have control over conducting widespread toxicity tests, in many cases it is important and may be feasible to perform site-specific toxicity testing in order to determine the effects that chemicals or other compounds may have on our surrounding environment and health.

How Toxicity Tests Work

Most toxicity tests examine a specific type of adverse effect, known as an endpoint. For example, a test may try to determine whether a particular substance may potentially cause cancer. Other tests are more general in nature and seek to determine whether a subject or series of subjects (environment, animals, humans, etc.) are affected after being exposed just one time (an acute study), multiple times (repeat dose studies) or over the course of a specific duration (chronic studies).

There are three main phases of risk assessment in relation to toxicology testing. They include:

• Hazard identification – Determining what result the toxicity of a substance may have on the environment or humans. Once the response to toxicity is determined, then testing can be done to determine how responses occur based on different exposure levels (dose-response assessment) and whether there is an exposure level below which adverse results do not occur (no observed adverse effect level).
• Exposure assessment – Determining what sector of the environment, humans, or animals have been exposed to the toxic substance, including how often or how long the exposure has taken place.
• Risk characterization – This combines the first two phases of hazard identification and exposure assessment to determine an estimate of the actual environmental or health risk.

There are numerous methods used to perform site-specific toxicity tests depending on what is being tested and where the test is being performed. Most site-specific toxicity testing is conducted by obtaining samples taken from the site (e.g., soil, water, plants, fish, sediment, wildlife, etc.), by placing organisms within enclosures at the site to perform testing, or by measuring the toxicity of organisms that are already present at the site. These types of tests are called ex situ tests, in situ tests or field tests, respectively. Environmental toxicity tests have also been performed using animals and other high throughput methods developed in the pharmaceutical industry.

Types of Environmental Toxicity Tests

While environmental toxicity testing is varied, depending on the location to be tested, the suspected toxins and many other factors, most environmental testing is performed using some sampling of soil, water, plants, organisms, animals or other components in or around the testing site. Testing methods are numerous and vary by the research laboratory commissioned to perform the test and other criteria related to the testing environment. Some types of environmental testing that may be performed include:

• Sediment Studies
• Whole Effluent Toxicity Testing
• Bioaccumulation Studies
• Laboratory Flow Through Testing
• Chemical Product Testing
• Aquaculture and Mariculture Research
• Endocrine Disruptor Studies
• Ion Imbalance Toxicity Evaluations
• Bioassay Testing

Why Toxicity Testing Is Important

There are many instances where environmental toxicity testing benefits the surrounding ecosystem and human population, or where it may be required by law. Industries may be required to test the effects of the chemicals they use or the processes they employ on the surrounding environment. Water utilities may use screening tests to determine the presence of dangerous water contaminants due to spills, accidents, sabotage or terrorism. Homeowners or building owners may be interested in determining the level of contaminants contained in surrounding water or soil samples.

The importance of identifying and assessing contaminants and toxic compounds in our environment cannot be underestimated. Although there may not currently be enough government regulation in regards to environmental toxicity testing, regulatory agencies in recent times have been paying increasing attention to the assessment of toxic contamination in the environment, and most especially in the aquatic ecosystem. Businesses and individuals can commission their own environmental toxicity studies to ensure the safety of the environment and human health, even in the absence of government regulations.

Numerous companies can be commissioned to perform site-specific toxicity testing for industry, business and home needs. More widespread toxicity testing is usually commissioned by government agencies or other large organizations. Many of the companies that offer environmental toxicity testing are research laboratories that help clients identify, monitor and eliminate toxic discharges.

Interested in finding environmental toxicity tests and test providers? Check out our Toxicity Test Directory. For more about toxicity testing, read our interview with Martin Hilovsky, toxicity test expert.