Even though many chemicals that have been found to be harmful to the environment have been banned or are strictly regulated in the U.S. or Europe, they remain legal to use in less-developed countries, including many countries that grow coffee. This is troubling on many levels, beyond the fact that dangerous chemicals are being applied to crops.
For instance, workers in these countries may be less likely to be well-informed about the dangers of the chemicals, less likely to be provided with protective gear, and less informed about proper application methods (see this abstract, for example). These regions are also much higher in biodiversity and ecosystem complexity, increasing the risk to the environment.
Here are just some of the more common chemicals used on coffee farms to control major pests and pathogens (which were described in a previous post). I’ve included the World Health Organization classification, based on human risk. Click on the link for more information.
Endosulfan (brand name Thiodan) — used against coffee cherry borer. (UPDATE: As of early 2011, Endosulfan has now been slated to be banned globally, although it does not take place immediately). Does not dissolve readily (but does degrade) in water and sticks to soil particles, so may take years to completely break down. Its breakdown products are more persistent than parent compounds. It is toxic to mammals, birds, and fish. Effects the central nervous system, and in animals causes kidney, testes, and liver damage. Class II (moderately hazardous). Colombia has considered endosulfan worse than the coffee cherry borer. In that country, more than 100 human poisonings and one death were attributed to endosulfan use in coffee during 1993; more than 100 poisonings and three deaths were reported in 1994. Here is an article on growing coffee without endosulfan.
Chlorpyrifos (brand name Dursban). A broad spectrum organophosphate used against coffee cherry borer and coffee leaf miner. In the U.S., the Environmental Protection Agency banned most household uses in 2000. It is a contact poison. It has caused human deaths, and has been linked to birth defects. It is extremely toxic to birds, freshwater and marine organisms, bees, and other wildlife. It can bioaccumulate and effect bird reproduction. Class II. A recent report on exposure and risks (especially to children) of chlorpyrifos from the Organic Center is here.
Diazinon (brand name Basudin). Used against coffee borer. Not very toxic to mammals unless inhaled, it is nonetheless highly toxic to wildlife and beneficial insects, and acutely toxic to birds. In the U.S. where it is still commonly used on turfgrass, diazinon has caused the second largest number of total known incidents of bird mortality of any pesticide. Class II. Another profile here.
Disulfoton. A systemic organophosphate insecticide used against leaf miner. In the U.S., restricted use due to its high toxicity to mammals by all routes of exposure. It is also highly toxic to birds and fish. Secondary exposure and poisoning occurs after birds feed on insects that have consumed residue-laden plants; these insects are impaired by the disulfoton and are easier for birds to capture, compounding the problem. High levels of toxins can be attained in this manner and has resulted in avian mortality in connection with disulfoton use. It is delivered in granular form, which poses the threat of runoff and contamination of other crops when applied on slopes, on which coffee is often grown. Degrades or is metabolized by plants into harmful compounds that are very persistent in the environment. Class 1a, extremely hazardous (highest toxicity). Another profile here.
Methyl parathion (a.k.a. ethyl parathion, parathion). Organophosphate used against leaf miner. One of the most toxic pesticides, highly restricted in U.S. Very toxic to birds when ingested or through skin exposure. Also highly toxic to animals and fish. Persistent in soil and will bioaccumulate. Areas sprayed with this chemical should not be entered for 48 hours. It is banned in Indonesia and restricted in Colombia, but Pesticide Action Network reports that there is evidence that methyl parathion is not used safely in Central America and is regularly misused in developing countries. Class 1a, extremely hazardous.
Triadimefon (brand name Bayleton). Copper-based fungicide used to against coffee rust. Only slightly toxic to birds, little is known about its effect on humans, but it is suspected that there is potential for reproductive problems with chronic exposure. It has been found to induce hyperactivity in rats. The major concern is that long-term use of this and other copper-based fungicides is copper accumulation in soils, such as been found in coffee farms in Kenya and in Costa Rica. Copper toxicity has been found in other crops grown in these soils, and copper impacts other biochemical and biological processes in soil, and little is known about long-term effects in tropical ecosystems. The primary metabolite of triadimefon is triadimenol, which is Class III (slightly hazardous). Another profile here.
Cypermethrin. A synthetic pyrethroid used against coffee cherry borer. Generally low direct toxicity to birds, but ingestion via contaminated insects causes mortality in young birds. Extremely toxic to fish other aquatic organisms, and should not be applied any place where it may drift into water. Class II.
Next in this series: Resources on organic coffee, and further reading.