Tests that mimic real-world conditions are better than standard models in showing how chemicals react to soil, water and air.
For people, persistence is usually considered a positive quality. Not so for chemicals, when getting labeled as environmentally persistent could kill the approval of a new product. Luckily Chris Lowrie, Head of Environmental Fate and Metabolism at Charles River Edinburgh, showed persistence in creating better persistence tests.
Drugs, agrochemicals, and industrial chemicals are all candidates for the sort of testing done by Lowrie’s team. In the EU especially, there are stringent regulations for controlling chemicals that could be introduced to the environment. The goal of regulators is to identify and restrict persistent organic pollutants (POPs) or persistent, bio-accumulative and toxic substances (PBTs), which are the kind of chemicals that do not degrade easily in the environment. POPs and PBTs can accumulate in the environment with repeated use, and can have harmful effects on humans and ecosystems.
The initial testing of new chemicals is standardized and required by most governments for risk assessment, but failing the first round of testing is not the end of the line for a product. Further tests can be done that mimic real world conditions better than the required standard tests to give a more accurate model of how the chemical will actually react to soil, water and air.
“The additional testing is designed to demonstrate that with modification of an environmentally relevant parameter, like light or temperature, the degradation rate can be much faster, which is a great thing for registrability of the substance,” said Lowrie.
Many contract research organizations, like CRL, offer extended testing to companies whose products have already gone through required government tests. However, these additional tests can be complicated and expensive, involving factors like field testing in ponds or controlled natural environments like mesocosms.
“The tests we offer are much simpler and therefore less expensive to run,” Lowrie said. “They provide very quick answers to whether a substance may or may not be persistent in the real world. We will deliver data in a matter of weeks or months rather than years in the case of some of the alternatives.”
One example of a modified test would be running a water/sediment study outdoors in natural sunlight instead of in the dark in the laboratory. This modification helps identify chemicals which are susceptible to both photolytic and biological degradation processes as the degradation rate and pathway may be directly and indirectly influenced by sunlight.
Lowrie’s team has discovered that with minor subtle modifications, such as designing appropriate apparatus for outdoor use or incorporation of light/dark cycles, testing conditions can be designed which generate relevant data that can be used to determine whether or not a substance will be truly persistent.