(F.A.C.T.) Fair Agricultural Chemical Taxes
Home | Credits | Table of Contents | Footnotes | State Profiles | Contact
|
||||||
 |
 |
Well into the 1970s, the general wisdom espoused by chemical makers, water supply experts, and regulators was that agricultural chemicals applied according to directions would break down into non-toxic compounds before reaching water-yielding strata or "aquifers" below the ground surface. The conventional wisdom began to unravel, however, with the discovery in 1979 of the soil fumigant DBCP and the insecticide aldicarb in the groundwater in several states. The initial response to these findings downplayed the implications: "the applicators may have erred, the chemicals involved were somehow unusual, the local environment and hydrogeology were particularly sensitive to contamination." Soon, however, it was clear that these seeming aberrations were far too common.134, 135
Today, environmental researchers report that pesticides or their chemical breakdown products — often called "metabolites" — have been found in the groundwaters of forty-three states. At least 143 pesticides and twenty-one metabolites have been detected.136 The geographic coverage of groundwater monitoring remains spotty, but localized studies and several nationwide investigations have laid to rest any doubt that common legal application of pesticides can and does affect groundwater quality.137, 138 It is now recognized that agriculture contributes more than half of the pollution entering the nation's rivers and lakes. Years of studies have identified it as the greatest source of water pollution in the United States.139, 140, 141 The National Water-Quality Assessment (NAWQA) Program — The National Water-Quality Assessment (NAWQA) Program, a major undertaking by the U.S. Geological Survey, is designed to examine the quality of both groundwater and surface water and is beginning to provide useful comparative data on water resources across the country, including information on the occurrence of pesticides and nitrates. Under the program fifty-nine "study units," covering nearly 40 % of the contiguous U.S. and encompassing almost 70 % of water use, will be examined on a staggered research schedule reaching beyond the year 2000. Detailed study plans have been developed, including analyses of land uses in the watersheds that make up each unit and selection of numerous monitoring points. In NAWQA's Pesticide National Synthesis Project, data collected thus far shows widespread occurrence of pesticides in streams and groundwater, with detection patterns generally correlated with land use and pesticide use patterns. This correlation was strong for streams and major rivers, but less so for groundwater, where the influence of unique local hydrogeologic conditions could be seen. Seasonal patterns could be discerned in many instances, with pesticide levels peaking after times of heavy usage and declining in the following months. Exceptions to the common seasonal patterns appear to be for those surface waters where pesticide-contaminated "base flows" from groundwater contribute to the stream volumes in times of low rainfall. The study investigators also note that higher levels tend to last longer in reservoirs than in free-flowing streams. For urban streams, which showed the highest insecticide concentrations, these "seasonal pulses" likewise tended to last longer. As USGS staff explain the "most striking findings":
What's more, the data indicate that "...most pesticides found in the environment usually occur as mixtures," with an average of seven pesticides found in each stream sample. As Robert J. Gilliom explained in a March 1999 briefing on Capitol Hill, "Most stream samples with detections had five or more compounds and most ground-water samples with detections contained two or more pesticides." USGS points out that the "good news" of these investigations has been that where federal drinking water standards or health advisory levels have been set (for a minority of the pesticides detected), these levels are exceeded infrequently on a year-round basis. Seasonal exceedances, lasting weeks or months, however, are not uncommon. EPA drinking water standards, however, address the health effects of single substances only and do not account for any possible additive or synergistic effects of chemical mixtures. In fact, the existing standards also fail to consider the metabolites or breakdown products of the "parent" pesticide, despite the fact that in many instances, detection of these metabolites is actually more common than detection of the pesticide itself. The weedkillers used on corn and soybeans — namely, atrazine, alachlor, cyanazine, and metholachlor — are the principle contaminants found.142 Currently used insecticides frequently detected are carbofuran and diazinon.143 In addition, the NAWQA data also show that there is "a high potential for pesticide impacts on aquatic life in some streams." Since EPA water quality criteria to protect aquatic organisms have been established for only twenty pesticide compounds, the survey staff compiled aquatic life water-quality guidelines developed by EPA as well as the International Joint Commission and Canada. They compared monitoring data to those standards and noted that guidelines "were exceeded for variable lengths of time in more than half of the urban and agricultural streams sampled." More than 70 % of urban areas studied had concentrations of one or more insecticides that exceeded a guideline. Notes USGS staff, "long-term exposure to low-level mixtures of pesticide compounds, punctuated with seasonal pulses of high concentrations, is an exposure pattern that may not be adequately accounted for in present criteria". In the NAWQA Nutrients National Synthesis Project, nitrate concentrations are generally higher in agricultural areas and especially in groundwater in areas intensively cultivated for row crops, such as corn, cotton, and vegetables. These areas receive some of the highest rates of inorganic fertilizer and irrigation. Concentrations in 12 % of the home use wells exceeded the EPA's 10 mg/liter drinking water standard. Additionally, eutrophication results when nutrients accumulate excessively in streams, lakes, and in coastal waters. Excessive algae growth then removes oxygen from water producing a foul taste and smell, and can result in fishkills.144 As this ambitious NAWQA program moves forward documenting the extent of pesticide and fertilizer contamination of water, more areas will be studied and the number of data points from which to draw conclusions will increase substantially. Hopefully, the end result will be a better understanding of current patterns and indications of policy changes needed to decrease the impact of pesticides on water resources. Highlights of the twenty study areas in agricultural regions are cited under each of the state profiles (see appendix of this report). Soil Excessive synthetic nitrogen use not only leaches into the groundwater, but thirty-seven years of data collected from a plot at the University of Wisconsin in Madison shows that excess fertilizer is literally aging the soil irreversibly through acidification. Cation exchange capacity, or the ability of the soil to hold onto molecules of calcium, magnesium, and potassium, is compromised by the excessive soil acidity.145
Air and Atmosphere The USGS has also begun assessing the impact of pesticides in the atmosphere drawing from existing data gleaned from 132 studies. Highlights show that all of the pesticides studied are being detected in rain or air, but many that are used have never been studied. Various organochlorines (currently banned from use), organophosphates, triazines, and acetanilides which are among the major classes of pesticides described in the chart below, have all been found. Pesticides have been detected in the atmosphere in all areas of the nation sampled. As expected, the highest atmospheric concentrations of pesticides occur seasonally in high-use areas when applications are greatest. Low levels of long-lived pesticides, some of which were banned years ago, are present in the atmosphere all of the time.147 In a recent report discussing the inadequate implementation of the California's State Toxic Air Contaminant Program, nineteen of the twenty-six pesticides monitored were detected in ambient air in and around California communities from 1986 to 1998. Sampling was not done in forty-two out of fifty-eight counties nor for the nearly 100 pesticides prioritized as airborne contaminants.148 Another important and heavily used pesticide is methyl bromide. It is acutely toxic and threatens the health of workers as well as neighboring communities. It is a major global threat since it is a potent depleter of the Earth's ozone layer, fifty times more destructive than chloroflourocarbons (CFCs).149 It is used heavily as a soil fumigant in the cultivation of fresh market tomatoes, strawberries, and grapes, for example. It is also used in commercial food storage to increase shelf life during transportation. In addition to conventional farmers using excessive amounts of synthetic nitrogen that is acidifying the soil and contaminating our water bodies, inorganic fertilizers release a form of nitrogen that bonds easily with oxygen and volatizes into the atmosphere. Excessive amounts of volatized nitrogen are implicated in global warming.150, 151 Alternatively, the use of composted animal manure or the "green manure" of nitrogen-fixing cover crops improves the soil's fertility, water-storage capacity, and tilth (structure) while maintaining a healthy population of microbes, earthworms, ants, and other beneficial insects.152
CONTINUE TO:
|
Additionally, it has been recently discovered that 270 million pounds of hazardous waste, such as steel mill smokestack ash and air pollution scrubber brine, was sent to more than 600 fertilizer companies in forty-four states between 1990 and 1995, presumably for use as raw materials in fertilizer production. Since there is almost no monitoring of fertilizer or soil contamination levels, actual soil contamination is unknown.146