Chemicals are routinely tested on lab mice before they're placed on the market. A new technique used in a University of Georgia lab may reduce the number of mice needed for testing.
Phil Williams, an environmental health scientist with the UGA College of Agricultural and Environmental Sciences, uses microscopic worms called nematodes to determine the toxicity of chemicals.
Worms Cost Less and Work Better
"When new chemicals are developed, at some point, animal testing is required," Williams said. Using animals in testing requires proper facilities and a lot of money.
"Plus, many people don't like mice, or any animals with fur, being used for these tests," he said
The nematode Williams uses, Caenorhabditis, is found naturally in the soil. Its nervous system functions much like that of humans. "It can't show everything in relation to humans, but there's a lot we can learn from it," Williams said.
Mice and rats, most commonly used for laboratory testing, aren't always the best choices. "The closer biologically an animal is to a human, the more likely we can predict human reactions," he said.
Won't Replace Higher Animals
Williams is finding nematodes very effective in early stages of toxicity testing. But he doesn't expect them to replace other animals entirely.
"At some point, higher animals are always going to have to be used," he said. "There are some things you just can't learn without using higher animals.
Nematodes' effectiveness in testing for toxicity could reduce the number of new chemicals tested.
"A company could make a thousand new chemicals and could never afford to screen them all using higher animals," he said. "Using the nematode, we can easily and quickly determine which new chemicals to continue testing."
For chemical testing, nematodes are still in the development stages. But on the environmental side, they're much closer to being used outside the lab.
Quicker Soil Tests In Less Soil
"Since it's a soil organism, I've use it to predict environmental affects of chemical exposures," Williams said. He also uses them when testing soil samples for toxicity.
Earthworms are used for soil tests, too, but they require a larger soil sampling, and results take up to 14 days. The nematode test uses just 3 grams of soil and gives results in 24 hours.
"Earthworms require about 400 grams of soil for testing," Williams said. "When you're working with hazardous soil, you'd much rather work with just 3 grams."
Analytical soil tests are so advanced they can detect minute amounts of chemicals on a site. But detection isn't enough.
"The biological effects to humans and animals aren't answered by these tests," he said. "You have to use organisms to see what the biological effect will be."
In December, the American Society for Testing Materials plans to vote on adopting the use of nematodes for soil testing.
Used For Food Science Testing Too
Nematodes may have other uses, too. Williams is working with UGA food scientists to detect food-borne pathogens. Nematodes appear to have great potential in detecting clostridium botulinum, the organism that causes botulism.
"Botulism affects the nervous system, which makes the nematode a perfect testing specimen," he said.
Williams also uses nematodes to test new medical imaging agents for a pharmaceutical company. "These agents are taken internally for medical diagnostics and then traced through the body," he said. "The company can chemically make these products fairly easily, but screening and approval is a long process." Nematodes can greatly streamline the screening.
In the future, Williams sees nematodes greatly reducing the number of mice and rats used in laboratory testing.
"You could release a chemical into the environment for 20 to 30 years and then look back and see what the effects were, but that's not ethical," Williams said. "You could expose humans to the chemicals, but we would never do that. So we have to use animal models to try to help us predict effects."
(Sharon Omahen is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.)