Science Debunks Precautionary Principle

Published February 1, 2004

The problems of the “precautionary principle” received a thorough airing from its critics at a December 12 forum sponsored by the George C. Marshall Institute, a Washington DC-based think tank focusing on science policy. The forum at the National Press Club, “Uses and Misuses of Science in Regulating Chemicals: Unintended Consequences for the Developing World,” reviewed application of the precautionary principle to new biotechnology products, old restrictions on DDT, and new restrictions on a tried and true herbicide, paraquat.

Henry Miller of the Hoover Institution, founder of the Food and Drug Administration’s Office of Biotechnology, noted environmental organizations don’t seek “prudent, safe use” of such old chemicals as paraquat or new biotechnology products, “but their complete elimination.”

“A large number of people in poor nations have food allergies,” Miller pointed out, including to such common foods as milk, wheat, and nuts. “Biotechnology can remove the allergens … so people in developing countries can enjoy some of these foods.”

But environmental groups such as Greenpeace are using the precautionary principle to oppose development of those products and others that would improve agricultural productivity, Miller argues, not because they are dangerous, but because they are at odds with a social vision that is “anti-business, anti-technology, and anti-American.”

DDT Essential for Fighting Disease

Roger Bate of the health advocacy organization Africa Fighting Malaria pointed out that the restrictions placed by developed nations on the pesticide DDT are especially dangerous to the health of people in poor countries.

The European Union’s targeting of 12 chemicals, including DDT, based on the precautionary principle, Bate said, ignores “the risk profiles of nations at different stages of development.” Poorer nations simply can’t afford some of the controls rich nations place on the use of many pesticides, he argued.

DDT, Bate said, is vital to combating malaria and dengue fever–scourges that still kill hundreds of thousands of people in developing countries. The developed world’s controls on DDT, which can delay imports for nearly six months, are leading to black markets and the development of less-safe imitation chemicals, he said.

The precautionary principle’s prescriptions, he said, “have hampered trade, are hurting economic growth, and are damaging health.”

Paraquat a Benign Crop Maximizer

Some of the most serious questions about motives behind the use of the precautionary principle by environmental groups came from the presentation by Prasanna Srinivasan of Business Environment Assessments, an expert on developing countries’ economics.

Srinivasan released a new study sponsored by 30 organizations from 13 countries, titled “Paraquat: A Unique Contributor to Agriculture and Sustainable Development.”

Paraquat is the most widely used herbicide in the developing world and has come under increasing attack by environmental groups, which claim it is dangerously toxic to humans.

“In addition to health hazards, regulators are concerned that the chemical is persistent and accumulates in soil. Studies indicate that paraquat has adverse effects on mammals, birds, fish, and amphibians. In Sweden we believe that, for the environment and for health, the only safe use is no use,” Göran Eklöf of the Swedish Society for Nature Conservation argued last fall when a European Union scientific committee found paraquat safe for use in the EU.

Srinivasan finds most such claims to be simply false. With respect to persistence in soil, for example, Srinivasan found paraquat is “environmentally benign.” It binds to clay soils and doesn’t affect soil life or leech into groundwater. It degrades and “doesn’t create any toxic effects in the breakdown,” he said. Further, because paraquat doesn’t destroy roots, it prevents soil erosion, which is especially important in tropical regions, Srinivasan argued.

As to human health effects, paraquat droplets are such that inhalation poses little health threat, although it can under some circumstances lead to bloody noses, Srinivasan found. It doesn’t absorb through the skin and can be washed off, he noted. Syngenta, the major maker of paraquat herbicides, has added a foul smell, dye, and an emetic to help prevent and protect against any accidental ingestion of the herbicide.

“The big problem is if there is deliberate consumption for the purposes of suicide,” Srinivasan found. Pesticides are a popular tool in suicides, he noted, and as one of the more common pesticides, paraquat is among those most often used.

According to the Food and Agricultural Organization and World Health Organization, paraquat “may be absorbed through the gastrointestinal tract. Paraquat is not absorbed to any great extent by intact skin and there is no evidence of significant absorption from spray mist. … Repeated daily six-hour exposure of rats to paraquat aerosols over a three-week period produced signs of lung irritation but no deaths. … Fish–Not hazardous: rapidly absorbed by aquatic plants and inactivated in mud. Birds–Not highly toxic. No hazard under normal conditions of use. … Protective clothing should be provided for those handling concentrates. Adequate washing facilities should be available close at hand. Eating, drinking, and smoking should be prohibited during handling and before washing after handling.”

Paraquat and other pesticides, Srinivasan argued, serve a vital need. Even with them, annual crop losses amount to between 33 and 42 percent of world production. Without pesticides, though, crop losses would reach 80 percent. And without the productivity enhancements such chemicals provide, the world would use more than double the 38 percent of arable land now used for agricultural purposes–an additional 14.1 billion acres, or 44 percent of the land available on Earth, Srinivasan said.

So, why do environmental groups lobby to restrict pesticide use, and ban paraquat in particular? Why are environmental groups attempting to intimidate the EU science commission that approved the sale of paraquat in Europe?

To Srinivasan the answer is that “certain extremist environmental groups … seem to be more concerned with power than the truth.” In place of the precautionary principle, he offers a proposal of his own: “To protect the farmers’ rights wherever they may be to use whatever products and technologies they need.”

Duane D. Freese is former member of the USA Today editorial board and a columnist for Tech Central Station (, where this essay first appeared.

For more information …

The report by Prasanna Srinivasan, “Paraquat: A unique contributor to agriculture and sustainable development,” released by the Marshall Institute on November 1, is available on the Internet at