IN RELATION TO RACHEL CARSON’S SILENT SPRING
Christina Casanova
Michael Derby
George Koutsothanasis
Population density results from the
interplay of births, deaths, immigration
and emigration of organisms in an
environment.
In an attempt to control and decrease
the population density of just insects and
unwanted plants, all of our environment
has suffered the harsh effects caused by
insecticide sprays such as DDT.
The chemicals sprayed by the
Department of Agriculture have altered
the life history traits of organisms in the
area such as birds, insects, and soildwelling organisms.
Some of these organisms have even
grown a resistance, or immunity, to the
poisonous chemicals, creating an even
bigger population problem for the
environment.
Unfortunately, most organisms that live
through chemical spraying become
sterile. This completely throws off
reproduction rates and a region’s ability
to reach its potential carrying capacity.
An exponential growth model shows
possible growth in an unlimited
environment. When pesticides and
insecticides are introduced, an
environment becomes limited.
Populations are regulated by both biotic
and abiotic influences.
Instead of letting nature take its course,
humans are compelled to control and
convenience the environment to
themselves.
 An eco-friendly alternative to chemical
spraying would be providing more
predators of unwanted organisms or
spending more money on the sanitation
of disease ridden plants.
Chemical spraying affects the global
human population as well. Humans are
permeable. As toxic gases are entering
the lungs of humans and poisonous
chemicals rain down on cities, they stay
there.
More and more people are
reporting sicknesses and fatalities
to chemical poisoning as spraying
continues to be condoned by the
United States Department of
Agriculture.
Rachel Carson’s “Silent Spring” reveals that while
humans affect all environments we come in contact
with, the “new” environment thus created, may in many
aspects affect both population density and dispersion.
Chemicals, “The devils of mans’ own creation” affect
both death rates and reproductive rates, which in turn
affect survivorship curves and demography.
Along with such, chemicals affect behavior,
physiology, and development, having the affects to
kill and alter both the ‘good’ and the ‘bad’.
While a typical exponential population model
represents population in an unlimited, idealized
environment, other factors, many of which are listed
in Rachel Carson’s “Silent Spring” (I.e. malathion,
and DDT), alter the models efficiency, increasing
death rates and adding restrictions on the abilities
of organisms.

In comparison, unlike the typical logistic grown
model, the per capita rate of increase would either
increase or decrease as the carry capacity is or is
not reached.
Rachel Carson reveals that DDT and other pesticides
affect human population (our global human population
and carrying capacity) on an “irrecoverable” level.
Regional patterns of population are altered by mans assaults upon the
environment (“the contamination of air, earth, rivers, and sea.”), where the
applications of chemicals in agricultural are concentrated.
The global human population has been growing exponentially since 1650. This
is especially threatening, because an increasing number of humans means an
increasing demand for land. As soon as that land gets settled on, people are
going to want to grow crops and control unwanted “pests.” Since these pests are
constantly developing an “immunity” to pesticides, humans must make them ever
stronger and more lethal.
Infant mortality in humans may increase if we continue to use carcinogenous
pesticides, that may be fatal to newborns. Even if the infant doesn’t die, it may be
born with defects and disorders.
The life expectancy at birth is also a factor that is affected by pesticides. If
infants are exposed to poisonous chemicals from such a young age, then they will
not be expected to live as long as they should.