Human Health and the Environment

Toxicology lab image CAMI (Civil Aerospace Medical Institute) scientists conduct research to detect and measure drugs, alcohol, toxic gases, and toxic industrial chemicals in victims of fatal aircraft accidents as a contribution to the analysis of accident causation.

Disease is the result of an internal disorder of an organism, most often due to an external cause. Disease can be the result of infectious agents like viruses and bacteria, or non-infectious agents such as heart disease and sickle cell disease. The cause of many human diseases or poor health can be linked directly or indirectly to the environment.

Health is often a reflection of our environment; in our industrialized society we are constantly exposed to human-made chemicals including pesticides; additives in processed foods, such as coloring and preservatives; genetic and chemical modification of food such additions or artificial fats and sweeteners; exposure to tobacco smoke; exposure to air pollutants such as ozone; exposure to chemicals in gasoline and household cleaners; and exposure to heavy metals such as mercury or lead. Some of these exposures are routine in our culture, while others are the result of intentional acts of poisoning or polluting. In 1956 in Japan, there was an influx of patients with similar nervous system damage which was named Minamata disease for the affected city. It was determined by 1963 that the cause of the disease was methyl mercury poisoning from eating contaminated shellfish from the bay, and eventually linked to the local production of acetaldehyde by the Chisso Company and the dumping of waste into the nearby harbor.

Map image indicating the location of the Chisso factory

Environmental disease is not only a condition of developed societies as even cultures who have lived directly off the land suffered from exposure to naturally occurring toxic substances leading to health issues. Water, soil, and air can hold naturally occurring hazards: such as toxic metals in soil and water, poisonous outgassing of volcanos to pathogenic organisms, and have these have always been a part of our world. The goal is to recognize the sources and causes of potential human health risks present in the environment.

In toxicology, chemicals known to be toxic are studied and the risk evaluated. Pollution refers to an environment or part of an environment that has been contaminated in some way to make it unusable or simply unclean. The methyl mercury in Minamata Bay was not visible and the shellfish survived the contamination, but the people continuously exposed suffered greatly and many of the children born to exposed mothers have profound birth defects. Mercury is a toxic metal known to biomagnify in the food chain. Other toxins, when present together, can magnify the effect; this is known as synergism and is important to consider when looking at all factors in an environment.

As you move through this module, pay careful attention to the units. Often very small amounts of toxic substances can have a dramatic impact. Please review the following units before beginning the assignments in this lesson.

parts per million (ppm)
parts per billion (ppb)
In some toxicology studies, the units used are milligrams of toxin per kilogram of body mass
Concentration may also be recorded as a percent. For example, 100 ppm (100 mg/kg) is equal to 0.01%
In water pollution, units of concentration for a pollutant may be milligrams per liter (mg/L) or micrograms per liter (μg/L).
Air pollutants are commonly measured in units such as micrograms of pollutant per cubic meter of air (μg/m³)

Self-Assessment: Toxicology Problem Set

In this assessment, you will learn the basics about the impact on human health of toxins or chemical hazards. Please click here to download this toxicology file with the instructions and read all of the information carefully. Then answer the questions on the site. Make sure that you are able to answer these types of questions on your test.

RESOURCES IN THIS MODULE ARE OPEN EDUCATIONAL RESOURCES (OER) OR CREATED BY GAVS UNLESS OTHERWISE NOTED. SOME IMAGES USED UNDER SUBSCRIPTION.