Uses and Environmental Pollution of Biocides - Pesticides: Evaluation of Environmental Pollution - page 17

on various food and feed commodities. These limits are set to protect humans from harm-
ful levels of pesticides in their food (US EPA 2000). Residue levels found in food are usually
below the tolerance levels. Tolerances for a given pesticide may vary for different crops.
EPA has set tolerances for about 400 different pesticides. Since a pesticide may be used on
many different crops, there are about 9700 tolerances in effect.
Although there is little information on pesticide residues in food for developing coun-
tries, particularly food intended for local consumption, export crops are analyzed for resi-
dues to protect consumers in developed nations. Vegetables and fruits appear to receive
the highest pesticide doses and may contain high levels of residue.
1.3.4 Biodiversity Loss
In 2010, the UN International Year of Biodiversity, the PAN Europe review summarized
recent research findings from the scientific literature on the impact of pesticides on biodi-
versity and concluded that pesticides are a major factor affecting biological diversity glob-
ally, along with habitat loss and climate change. They can be directly toxic to organisms or
cause changes in their habitat and the food chain (PAN Europe 2010).
Pesticides are toxic products designed to kill a target organism; however, they also kill
other nontarget organisms such as the natural predators of the pest and organisms that are
beneficial to the health and balance of the ecosystem (WHO 2003).
There is growing concern about the health consequences of biodiversity loss and change.
Biodiversity changes affect ecosystem functioning, and significant disruptions of ecosys-
tems can result in loss of life-sustaining ecosystem resources. Biodiversity loss also means
that we are losing, before discovery, many of nature's chemicals and genes, of the kind
that has already provided humankind with enormous health benefits. Specific pressures
and linkages between health and biodiversity include biodiversity that provides numer-
ous ecosystem services that are crucial to human population's well-being at present and
in the future.
Over the past 40 years, the use of highly toxic carbamates and organophosphates
has increased dramatically and threatens exposed wildlife through their toxicity.
Organochlorines such as endosulfan, which are highly persistent, are still used on a large
scale. Pesticide poisoning can cause population declines, which may threaten rare species.
Pesticides accumulating in the food chain, particularly those that cause endocrine disrup-
tion, pose a long-term risk to mammals, birds, amphibians, and fish. But pesticides can also
have indirect effects by reducing the abundance of weeds and insects, which are important
food sources for many species. Herbicides can change habitats by altering vegetation struc-
ture, ultimately leading to population decline. Fungicide use has also allowed farmers to stop
growing “break crops” such as grass or roots. This has led to the decline of some arable weeds
(PAN Europe 2010). Miller (2004) reported that pesticide use contributes to pollinator decline,
destroys habitat (especially for birds), and threatens endangered species.
1.4 Out of the Impasse
Rapid growth in populations and the demand for food, coupled with degradation in the
human and environmental health and, recently, the challenge of climate change, acceler-
ated the search for alternatives to chemical pesticides.