17-06-2013, 03:19 PM
PESTICIDES: IMPACT ON HUMAN HEALTH AND ENVIRONMENT
PESTICIDES.ppt (Size: 2.6 MB / Downloads: 54)
Pesticide
A chemical used for controlling,preventing, destroying, repelling or mitigating troublesome or destructive animals, mostly insects;.Pesticides can range from herbicides(to control weeds), insecticides (insects), nematocides(worms) and fungicides(molds,mildews,rusts).Pesticides are commonly applied on farms,fruit orchards,golf courses and residential lawns and gardens
Historical Development of Pesticides
Pesticides are not new.Ancient Romans killed insect pests
by burning sulfur and controlled weeds with salt.In the
1600,ants were controlled with mixture of honey and
arsenic.By the late nineteenth century US farmers were
using acetoarsenic (paris Green),calcium arsenic,nicotin
sulfate and sulfur to control insect pest in field crops.An
emergence in pesticides use began after world war II with
the introduction of DDT,BHC, aldrin,Di-eldrin and 2-4D.
These new chemicals were inexpensive,effective and
enormously popular.DDT was especially favored for its
broad spectrum activity against insect pests of agriculture &
human health.Constant use of these pesticides harmed
non target plants and animals as well as left residue in
unexpected places.In 1962 Carson painted a grim picture
of environmental consequences of careless pesticides use
which resulted in the development of natural pesticides.for
eg.Pyrethroid insecticides are modeled after pyrethrins which is a
natural plant derived poison that have been used as an insecticides
How Pesticides Harm The Environment
Many pesticides are persistent organic pollutants (POPs). They move long distances, taken up the food chain, and accumulate everywhere.Examples: DDT, Endrin, Lindane, Endosulfan
Widespread application of pesticides leads to drifting and contamination of land and waterways
Health Effect Of Pesticides
The potential health effects of pesticides
depends upon the kind of and amount of
pesticides,how long the person has been
consuming the water and the person’s
overall health.
Acute Effects:
The acute toxicity of a pesticides refers to the ability of the chemical to cause injury to a person or animal from a single exposure,generally of short duration.Acute toxicity is determined by at least three methods:
Inhalation Toxicity: by breathing of vapors of the chemical
Oral Toxicity: Feeding the chemical to test animal
Dermal Toxicity: exposing the skin to the chemical
Acute toxicity is usually expressed as LD-50(Lethal dose) or
LC-50,which is the amount or concentration of a toxicant
required to kill 50 percent of a test population of animals under a
standard set of conditions