Biocide

A biocide is a substance that kills living organisms. Carson uses the term as an indictment of pesticides, arguing that they kill living organisms and life itself rather than just the insects and plants deemed pests. Though biocides still exist as a type of pesticide, Carson’s use of the term condemns pesticides as agents of indiscriminate harm.

Carcinogen

A carcinogen is a substance that is capable of causing cancer. Carson argues that many of the chemical pesticides profiled in the book have an established history of causing cancer in animals and seem to show the same effects in people as well. Carson also warns that their continued usage could lead to a terrifying future epidemic of cancer.

Ecology

Ecology is the study of living organisms and their relationships to each other and their environment. At the time Carson wrote Silent Spring, ecology was not an especially popular or well-known scientific discipline. However, she argues for the power of an ecological perspective precisely because of its understanding of and respect for the delicate, complex interdependence between all living organisms.

Forest Hygiene

Forest hygiene is a method of conserving forests that is widely used in Europe, and views the forest as an environmental space composed of more than just trees. Forests also include soil bacteria, birds, and insects. This approach, which is informed by ecology and natural control, seeks to allow nature to maintain itself through its already highly effective system of checks and balances rather than imposing manmade interventions. Implementing forest hygiene is one of Carson’s suggestions for a better approach to pest control.

Herbicide

Herbicides are pesticides that target specific plants, especially ones considered weeds. Carson’s objections to herbicides are similar to her concerns about pesticides and insecticides in general, namely that they kill more than just their intended target.

Natural Control

Natural control is the means by which nature itself polices dangerous or problematic species. Carson argues that, rather than using toxic chemical pesticides to eradicate pests, people can harness other forms of nature instead. An example of natural control is gypsy moths being kept in check by their natural enemies rather than through pesticide use.

Pesticide/Insecticide

Pesticides are chemical compounds that can kill species deemed to be pests. Insecticides are pesticides specifically designed to kill insects. Carson doesn’t dispute that pest control of some insects is needed. Her objection, instead, is to the widespread, unsafe usage of toxic chemical pesticides and insecticides. She also questions the logic of identifying some insects as pests when they are often important to the natural environment.

Potentiation

Potentiation generally refers to an increase in the strength of a substance. In terms of pesticides, potentiation means an increase in toxicity over time. Carson shares studies illustrating that combining pesticides leads to potentiation. She further notes that pesticides seem to become more lethal and dangerous over time, indicating they have hidden dangers still unknown at the time of her writing.

Sagelands

Also known as “land of the sage,” sagelands are a type of ecosystem in the high plains of the western United States. Because of the harsh conditions of the region, sagelands depend on the rugged sagebrush plant as a keystone species with which numerous animals and other plants are interdependent, including grouse, antelope, mule deer, and sheep. Carson uses the sagelands as an example of how herbicide campaigns can have devastating consequences, tracing how efforts to convert the region into grasslands by eliminating sage could lead to the collapse of the system that relies on it.

Systemic Insecticides

The term systemic insecticides refers to insecticides that work by making a plant or animal itself toxic to a targeted insect. Though chemical companies champion these types of insecticides as a groundbreaking advance in pest control, Carson finds them alarming and argues that they merely poison more living creatures—both the intended target and the vessel organism that has been weaponized against them.

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