The Precautionary Principle

What is the precautionary principle?
Simply put, the precautionary principle holds that it’s better to be safe than sorry. This principle states that evidence of harm, rather than definitive proof of harm, should prompt policy action. The principle also calls for the burden of proof to lie with manufacturers to demonstrate that chemicals are safe, rather than with the public to show that they cause harm.

What does the precautionary principle mean to environmental research on health-related issues?
The precautionary principle allows scientifically sound and ethical decisions to be made on environmental and public health problems. The principle shifts the burden of scientific proof onto those who produce or release chemicals to study the effects a substance has on humans and the environment. It calls for precautionary measures to be considered based on the strength of evidence that an activity or substance could be harmful to humans or the environment and the availability of lower-risk alternatives, even if science has not fully established a cause-and-effect relationship. Environmental research on health-related issues can contribute to the body of evidence used in these decisions.

Why is the precautionary principle important?
Putting chemicals into use before we understand the ramifications can be a dangerous practice. When Silent Spring researchers examined homes as part of the Cape Cod Breast Cancer and Environment Study, for example, they found DDT in two-thirds of the homes. DDT, which was banned in 1972, had lingered for more than 30 years.

The researchers also found the carcinogenic flame retardant tris (2,3-dibromopropyl) phosphate, banned in 1977—another signal that it’s better to keep chemicals out of our homes when we have good reason to suspect they will later be found harmful.

The precautionary principle holds that safety tests should be held in laboratories, not in our bodies.

To learn more, visit the Science and Environmental Health Network’s web section on the precautionary principle, especially the FAQs subsection.