Fumigant History: Still Poison After All These Years

On this page:

• Editorial from the August 2005 Global Pesticide Campaigner
• Resources

Editorial from the August 2005 Global Pesticide Campaigner

This issue of the Global Pesticide Campaigner highlights a particularly problematic class of pesticides—soil fumigants. These volatile chemicals are injected into the soil in large quantities—typically 100–400 pounds per acre—to kill nematodes, weeds, and fungi. Upwards of 90% of applied fumigants escape from the soil and are delivered to the neighbors at the whim of the prevailing winds; the rest migrates downward and contaminates groundwater.

Source: PANNA Archives.

Among the most toxic chemicals used for pest control, fumigants have poisoned many people directly and have caused sterility, cancer and birth defects, and contaminated groundwater supplies around the world. The history of fumigant use suggests that we humans are slow learners and haven’t quite wrapped our minds around the idea that there really is no free lunch.

Use of soil fumigants dates from the early years of the agrochemical revolution when no toxicity testing was required and the attitude was that if it didn’t kill you right away, it must be safe. As early as 1869, carbon disulfide was used to fumigate vineyard soils in France to kill Phylloxera, an insect pest that was devastating the European wine industry. Carbon disulfide is a severe central nervous system toxicant and causes sterility and birth defects. And it failed to stop the spread of Phylloxera. Importation of resistant rootstocks from America eventually saved Europe’s vineyards, but researchers continued to explore other chemicals that would attack soil pests.

Chloropicrin was introduced as a soil fumigant after World War I as the military was trying to find a use for the leftover stocks which they used as a chemical weapon during the war. Chloropicrin causes eye and respiratory irritation, nausea and vomiting, as well as permanent damage to the lungs. Agricultural researchers began experimenting with methyl bromide in the 1940s, a waste product first associated with manufacturing leaded gasoline that effectively sterilized soil, killing pests and beneficial organisms alike. It is a neurotoxicant also known to cause birth defects. In 1943, researchers developed a mixture of 1,3-dichloropropene and 1,2-dichloropropene as a soil fumigant. These compounds were later shown to be carcinogens and toxic to the liver, kidney and blood system and have contaminated groundwater extensively. In 1944, Dow introduced ethylene dibromide (EDB) as a new soil fumigant. EDB causes cancer and sterility in men and contaminates groundwater. Dibromochloropropane (DBCP), with similar toxicity and transport properties to EDB, was developed in 1955. Stauffer Chemical Company developed Vapam™ (metam sodium) in 1956, a chemical that has been responsible for multiple incidents of community poisoning in California.

Source: U.S. EPA

With agricultural researchers leading the way, chemical companies made their move in the mid-1940s to expand the markets for soil fumigants. They set out to “educate” farmers, recruiting the assistance of county extension agents to develop demonstration projects. Crop yields and chemical manufacturer profits increased, but at a price to those who did the applications and lived near fields, as well as to the Earth’s precious ozone layer that protects life on the planet from harmful ultraviolet rays.

It wasn’t long before the ill effects of these volatile chemicals became impossible to ignore. Workers who applied DBCP noticed that they were having difficulty having children. Semen analyses of over 26,000 men who were exposed to DBCP while working on banana and pineapple plantations showed that 24% had no sperm in their semen.

In 1977, the U.S. Environmental Protection Agency (EPA) began the process of phaseout, finalizing the ban in 1985. Other countries in the industrialized world were banning this chemical at the same time, although use continued in Central and South America and Africa. In December 2002, a Nicaraguan judge ordered three U.S. companies, Dow Chemical, Shell Oil Company and Standard Fruit (Dole Food Company in the U.S.), to pay US $490 million in compensation to 583 banana workers, a sum that has still not been paid to the workers. It is estimated that DBCP has sterilized thousands of Central American banana workers.

Also in the late 1970s, researchers at the National Cancer Institute reported on the carcinogenicity, reproductive and developmental toxicity of EDB, and the EPA took steps to prohibit its use. But it wasn't until a public outcry five years later over EDB residues in cake mixes, cereal and grain that EPA finalized the prohibition in 1983. The president of Great Lakes Chemical, which had promoted EDB as a pesticide, complained to reporters, “It was the media that created the problem…a great product has been taken off the market.” By that time, many groundwater supplies had been contaminated by DBCP and EDB, often to the point that municipal wells were closed and communities were forced to find alternate sources of water at great expense.

In the 1980s, scientists started to unravel the puzzle of the vanishing stratospheric ozone layer. UN scientists estimated that methyl bromide was responsible for 15% of worldwide ozone depletion in 2000. The Montreal Protocol, passed in 1987, put this chemical on track for a global phaseout by 2015.

In 1990, the California Department of Pesticide Regulation (DPR) suspended permits for 1,3-dichloropropene (Telone), after the state collected air samples that showed concentrations of the pesticide in air that greatly exceeded acceptable cancer risks. Four years and more than US $5 million in research and field trials later, DowElanco, the manufacturer of Telone, claimed to have developed application techniques that reduce drift and pushed DPR to reinstate use of the chemical. DPR complied with Dow’s request and has continued to lift restrictions to allow more use, even though air monitoring continues to show air concentrations near application sites nearly as high as when the chemical was pulled from use before.

So after all of this experience with toxic chemicals that contaminate our air and groundwater, we should be wiser now, right? Apparently not. The same story continues to play out this year as a new chemical, methyl iodide, is submitted to EPA for registration as a new soil fumigant. This chemical is so reliably carcinogenic that researchers who study cancer use it to induce cancer in mammalian cells. Using it as a soil fumigant results in extensive air pollution and groundwater contamination. Déjà vu.

We know what the chemical companies are thinking—$$profits$$! But we have to ask: What is EPA thinking? At a time when EPA, the U.S. Department of Agriculture, international development institutions and commodity groups all over the world should be actively researching and promoting the many successful non-toxic alternatives to fumigants, they are once again stepping into line behind the chemical manufacturers.

We need to face the facts we have learned over the last 60 years. The worker and bystander hazards of soil fumigants are impossible to prevent. Adverse health effects, groundwater contamination, ozone depletion, and mass poisonings of communities near application sites are all consequences of using these chemicals. Even the simplest analysis suggests that the present strategy of switching from chemical to chemical is neither safe nor sustainable, and fails to move agriculture towards less toxic methods of soil pest management.

It is time for us to move away from this archaic technology that relies on killing everything in the soil and look to modern methods of pest control work with nature, not against it. We are a clever species—we can figure this out, as pioneering organic farmers have shown us. All that remains is for our regulatory agencies to make decisions based on protecting human health rather than protecting chemical company profits.

Susan Kegley, PhD
Senior Scientist, PANNA

Resources

See the complete list of resources about pesticide drift.