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The issue of adding industrial waste to fertilizer and soil improvement products is important to the health of our citizens, to the safety of the food we eat and to the economic well-being of our farmers. The state is working aggressively to determine the full extent of possible environmental and human health effects resulting from this practice.
The state has committed three agencies and the Washington State University Extension Service to answer questions about the safety of using hazardous waste as ingredients in soil amendments and fertilizers. Recent news stories have cited examples of this practice across the U.S. The practice has received national attention. This fact sheet will focus on Washington State.
First, the Washington State Department of Agriculture (WSDA) tested a number of potato samples from farms in eastern Washington. Results showed very low levels of lead and cadmium – levels within Food and Drug Administration safe background levels. The Department of Health concluded that these levels were not a concern from a public health standpoint. However, these potato samples were not matched with the use of specific fertilizers, so they can not be used to draw conclusions about individual fertilizer products.
Some studies show the dietary intake of heavy metals has gone down in the past two decades. One literature review conducted recently by Associate Professor Allan S. Felsot of Washington State University, looked at “market basket" analyses of crops and other foods conducted over time by the U.S. Food and Drug Administration. He concludes:
“Historical trends in dietary intake show that exposure to arsenic, cadmium, and lead have decreased since the mid-1970s. ...the downward trend in metal intake suggests that soil amendments have not had a measurable impact on residues in food nor on dietary intake."
The Department of Agriculture began investigating fertilizer samples early in 1997. First, 19 samples were analyzed by a private laboratory for 27 elements including lead, cadmium, arsenic and zinc. According to Canadian Food Products Division officials and technical experts at WSDA, these 19 fertilizers would be in compliance with stringent Canadian standards developed for metals application to farm land.
Neither Washington state nor federal law requires that fertilizers be tested for their non-nutrient content. The state Department of Agriculture routinely tests these fertilizer products to ensure their nutrient value is as labeled. Under existing Washington State Department of Ecology regulations, some hazardous and solid wastes are recycled as ingredients for fertilizers and soil amendments. Examples of products made from waste-derived ingredients include liming agents and plant micronutrients, e.g. zinc. Besides the agricultural benefits some of these wastes can provide, they also may contain “tag along" contaminants such as heavy metals which provide no nutritive value to plants.
The Department of Ecology and WSDA conducted a screening study of fertilizers, with the help of a state Department of Health toxicologist and soil scientists from Washington State University. The results have been added to the information gleaned from the testing mentioned above. WSDA collected samples from 35 fertilizer products to find out what metals are in those fertilizers and whether or not it is a problem to use industrial by-products to produce fertilizers.
Six of the 35 samples were fertilizer products made from industrial by-products. Four of the samples were micro-nutrient sources that may be added to a fertilizer mix. The Department of Ecology’s Manchester Laboratory analyzed the samples.
Although the raw data are available for review, more analysis is needed in order to translate them into meaningful information. Many factors must be analyzed before any conclusions can be reached. For example: How much of each fertilizer product is typically applied to agricultural land (what is the application rate)? How much of the metal in question can be taken up by the plant? What information is available about factors that impact the uptake of metals by plants, such as the soil type, the acidity of the soil, and the crop type? Each of these can influence mineral uptake by plants.
The multi-agency team is looking primarily at the concentrations of heavy metals. Heavy metals can present hazards to humans and/or plants, depending on the concentrations and the amount applied to the land. The team is initially focusing on nine metals: arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium and zinc, and is looking at whether the metal concentrations in fertilizers could impact crops, human health and/or the environment. Where the concentration of a particular metal looks high to the team, it will need to be studied more closely.
The team from WSDA, Ecology, Health and WSU Extension is evaluating the results. They have compared the test results to standards that were developed for the agricultural application of biosolids (waste water sludge) as fertilizers. The U.S. Environmental Protection Agency (EPA) set standards for biosolids in order to limit unsafe concentrations of metals when biosolids are applied to farm land. Levels of metals in all of the fertilizer samples were lower than these human health risk-based levels established for biosolids. However, quality standards for treatment of biosolids are more stringent than the risk-based levels — and levels of arsenic, lead and cadmium in six fertilizer samples were higher than those quality standards. It should be noted that three of these samples came from fertilizer that does not contain industrial by-products. The multi-agency team will take a closer look at those products that exceeded the biosolid quality standards.
The biosolid standards have only been developed for nine toxic metals: arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium and zinc. Ecology also tested for 15 other metals for which no standards for comparison are available, but which are generally less toxic than the metals covered under the biosolids standards. All of the samples represent an initial screening of a limited number of fertilizer products in the state, and the results do not provide information on the variation of metals concentrations within products.
Canada does have limits on metals in fertilizers that were set to prevent the degradation of soil. All fertilizer products tested by the multi-agency team meet Canada’s standards.
The agencies and WSU Extension are moving ahead to gain a full understanding of the significance of the data. The results will be written in report form later this year. However, the team is committed to presenting findings to the public as specific conclusions are reached.
Ultimately, the team hopes to answer the following questions based on the data collected:
In response to Gov. Locke’s call for investigation and solutions, state agencies have proposed changes in fertilizer regulation that will strengthen and clarify review of industrial waste products used in fertilizers and soil improvement products. The agencies are also researching the processes used in other states and are consulting closely with EPA.
For help interpreting data tables, please call:
Dennis Bowhay, Department of Ecology at (509) 454-7866
Chris Chapman, Department of Ecology, (360) 407-7160
Ali Kashani, Department of Agriculture, (360) 902-2028
Denise LaFlamme, Department of Health, (360) 753-2410
Steve Fransen, Washington State University, (253) 840-4516 or
Shiou Kuo, Washington State University, (253) 445-4573
If you have special accommodation needs, please contact Chris Chapman at Ecology’s Hazardous Waste and Toxics Reduction Program at (360) 407-7160 (Voice) or (360) 407-6006 (TTY).
Copyright © Washington State Department of Ecology. See http://www.ecy.wa.gov/copyright.html.
