Agriculture Reference
In-Depth Information
produce accounted for $5.4 billion (40%) out of $13.6 billion total organic food sales
in the U.S. (Winter and Davis 2006). As much as 93% of organic fruits and vegetables
are sold in the form of fresh produce in this country (Dimitri and Greene 2002). It is
estimated that by 2010, organic fruit and vegetable sales in the U.S. will reach $8.5
billion, about four times the organic produce sold in 2000. In the U.S., California is
the leading producing state and Minnesota is the third largest producer in overall
organic food production. California is also the leading state in the U.S. in production
of organic fruits and vegetables.
Safety Issues Associated with Organic Fresh Produce
According to a number of consumer surveys, “safer foods” is one of the qualifi ers
often given to organic foods, but this perception is largely driven by the association
of “unsafe” and synthetic ingredients (Magkos and others 2006). In the case of fresh
produce consumers frequently consider that organic fruits and vegetables are safer
because they have less pesticide residues. Although the long-term health effects of
ingesting pesticide residues are yet to be corroborated, to date there is convincing
evidence that organic fruits and vegetables have signifi cantly lower prevalence
and concentration of pesticide residues than their conventional counterparts (Baker
and others 2002; Pussemier and others 2006). This consumer perception of safer
organic foods often ignores the microbiological safety issues resulting from organic
production practices.
Organic practices limit the number of synthetic inputs used in food production, and
in the case of fertilizers all synthetic compounds have been banned (NOP/USDA
2002a). According to the Organic Rule, farmers can use a variety of natural wastes as
organic fertilizers, but the most widely available and least expensive fertilizing mate-
rial is livestock manure. The organic regulations do not restrict the type of animal
manure used on crops, but in the U.S. the NOP established specifi c guidelines for its
utilization on crop fi elds (NOP/USDA 2002b). The Organic Rule recommends the
application of manure after composting, but it also allows the use of raw manure if it
is applied from 90 to 120 days before harvest.
The term
compost
is defi ned as “the product of a managed process through which
microorganisms break down plant and animal materials into more available forms
suitable for application to the soil … must be produced through a process that com-
bines plant and animal material with an initial C:N ratio of between 25:1 to 40:1”
(NOP/USDA 2002a). For composting, organic farmers using an in-vessel or aerated
pile system are required to maintain the compost pile at 131 to 170 °F for 3 days, and
users of the windrow system must maintain the compost material in the same tem-
perature range for 15 days, during which the materials must be turned a minimum of
fi ve times (NOP/USDA 2002b). Raw animal manure may be used only when it is
applied to soil at least 120 days prior to harvest of products whose edible portion
comes in direct contact with the soil surface or soil particles, and at least 90 days prior
to harvest of products whose edible portion does not come in contact with the soil
surface or soil particles.
The main food safety concern of organic fresh produce as a vehicle of foodborne
infections stems from the utilization of manure as crop fertilizer. Pathogenic bacteria
