FOR IMMEDIATE RELEASE
Contact: Roger Segelken
Office: (607) 255-9736
Internet: [email protected]
Compuserve: Bill Steele, 72650,565
http://www.news.cornell.edu
ITHACA, N.Y. -- Growers who follow U.S. Environmental Protection Agency
(EPA) rules in applying sewage sludge as fertilizer to their land may be
inadvertantly endangering human health, the environment and the future
productivity of their own crops, an analysis by the Cornell University
Waste Management Institute has found.
"The potential for widespread use of sludge on agricultural and residential
land, the persistence of many pollutants which remain in soils for a very
long time and the difficulty of remediation" warrant tougher rules than the
federal EPA and most state environmental agencies have established, the
university-based institute states in a new report.
Some states, including New York, have regulations in place that are more
strict than the EPA's "Part 503" rules, and producers and applicators of
sludge products in those states must follow the applicable state
regulations. However, no state's regulations are as strict as those
recommended by the Cornell institute, or as restrictive as
sludge-application regulations in some European countries and the Canadian
province of Ontario.
The August 1997 publication of "The Case for Caution: Recommendations for
Land Application of Sewage Sludge and an Appraisal of the U.S. EPA's Part
503 Sludge Rules" follows the earlier issuance of a bulletin from Cornell
Cooperative Extension. That bulletin urged greater caution in sludge
application to agricultural lands -- and no sludge or sludge compost
whatsoever on home gardens.
Explaining why a university-based organization is so vocal in opposing
federal agency rules, institute Director Ellen Z. Harrison said: "We
believe that the soil, water and crop conditions make these federal rules
particularly inappropriate in New York state and the Northeast. As the
land-grant university for New York state, it is Cornell's role to address
this issue.
"We're not making a case for prohibition of sewage sludge in agriculture,
but rather for more restrictive rules," said Harrison, one of three report
authors (along with Murray B. McBride and David R. Bouldin, professor and
professor emeritus, respectively, in the Department of Soil, Crop and
Atmospheric Sciences at Cornell).
"Clearly there are societal benefits to recycling this material and
potential benefits for agricultural productivity," said Harrison, a
geologist. "But we are concerned that the EPA -- in setting rules that are
far less protective than those of many other nations -- has made many
overly optimistic or simplistic assumptions about contaminant impacts. We
need to take a closer look at the contents of sewage sludges and the
conditions under which they are applied before we make decisions that will
affect agricultural productivity and human health, as well as the health of
the environment for years to come."
Also known as biosolids, sewage sludges are the byproduct of municipal
sewage-treatment processes. Separating liquids from treated sewage yields
wastewater effluents and truckloads of an organically rich material -- and
a waste-disposal problem for municipalities. Until ocean dumping was
outlawed, New York City and some other municipalities hauled sewage sludge
off-shore. Two legal alternatives, incineration and landfilling, cost
municipalities money. Land application of sewage sludge offers an
attractive option because municipalities can sell the material, or at least
contract with haulers to remove the material at lesser cost to taxpayers.
However, sewage sludge contains more than organic matter and agriculturally
useful chemicals like nitrogen and phosphorus. Depending on what
households, businesses and industries are flushing down the drains -- and
what is leaching from miles of pipes in every city -- untreated sewage
includes a mixture of heavy metals (such as lead, mercury and cadmium) and
toxic organic chemicals (such as PCBs), as well as pathogens (including
bacteria, viruses, protozoa and other parasites) from fecal matter.
Some sewage-treatment processes kill most pathogens, but heavy metals and
other contaminants are concentrated in the dewatered sludge. Humans and
other animals potentially can be exposed by contacting sludge contaminants
on the surface of soils and plants, through ground- and surface-water
movement of contaminants, and by eating plants that are grown in soils with
heavy metals and other contaminants.
The Cornell Waste Management Institute's report lists 14 reasons why the
EPA's sludge rules may not adequately protect human health and the
environment. Among them:
-- Contrary to EPA analysis, contaminants might find their way into
drinking water, according to analysts at Cornell. They concluded that low
mobility of contaminants is predicted by unrealistic laboratory simulations
of water moving through soil packed in columns, rather than soil with
natural channels created by worms, roots and other "macropore" processes.
A Cornell study published in 1997 found metals in water percolating from
fields where sludge was applied more than a decade earlier. Application of
sludge according to EPA rules could possibly result in a violation of
drinking-water standards in private wells, the report said.
-- Sewage sludge contains phytotoxic (or plant-damaging) metals, such as
copper, zinc and nickel that accumulate in soil and can reduce yields of
the same crops the fertilizer is supposed to help. High concentrations of
these metals also harm soil microorganisms that contribute to plant growth,
while other metals in sludges can create dietary imbalances in animals that
graze on plants growing in sludge-treated soil.
-- Consumers who follow the USDA's diet recommendations are eating more
plant-based foods than the EPA assumes -- and may be consuming more heavy
metals than the EPA predicts, the Cornell analysts found. They said the
EPA's risk-assessment for heavy metals in fruits, vegetables and grains is
incorrect because it based on the "average American" diet of the l970s
rather than the current American diet or the USDA-recommended diet with
even more vegetables, fruits and grains. For example, the "EPA diet" has
only one-fifth the amount of leafy vegetables (potentially a major source
of dietary cadmium, a toxic metal, when grown in some sludge-amended soils)
as the USDA-recommended diet. And the USDA diet contains 16 times the
amount of fruit that the EPA assumes Americans are eating.
-- The EPA does not require labeling of sludges and sludge products.
Without labels, the Cornell institute suggested, consumers may assume that
all sludge-based products are alike, when in fact the levels of
contaminants and other properties vary widely.
The "Case for Caution" report includes more protective recommendations for
farmers and for applicators of sewage sludge, as well as suggestions for
stricter policies and regulations on the state and federal levels and
advice for home gardeners who already have applied sludge products. The
Cornell institute was established in 1987 to address environmental and
social issues associated with waste management through research, education
and outreach.
-30-
EDITORS: News media copies of "The Case for Caution" are available from
the Cornell News Service, (607) 255-4206, [email protected]. The text of the
report is available at this Web site
--------------------------------
RSS