Introduction
Pollution represents the confluence of humans interacting with the Earth environment. Humans have always polluted their environment: just by living, we create a waste that wouldn’t be there if it weren’t for us. In the geologic past, this wasn’t such a problem because the human population on Earth was small enough that natural systems could compensate and dissipate the pollutants. Sometimes humans would just move away from a polluted area. But, as we know from our understanding of human population growth, exponential growth means exponential amounts of pollution: with nine billion people forecasted to be on Earth this century, pollution by humans has far exceeded the ability of ecosystems to handle it.
A paper mill in New Richmond, Quebec that lacks common pollution control equipment for soot. (Photo: Wright/Prentice Hall.)
Compound this with modern living which has also brought up whole new types of pollution: pollution by heavy metals that were once buried in the earth along with fossil fuels, and pollution by human-created molecules (e.g., pharmaceuticals and chemicals like PCBs), pollution by radioactive waste. While some types of pollution can be handled by our environment (bacteria and other microbes can break-down natural waste products), many of these “new” pollutants are persistent: they cannot be easily broken down by natural processes. The result of population growth, natural waste production, and these “new” pollutants means that Earth systems must contend with a myriad of pollutants.
In this module we will define pollution and explain how pollution is related to toxicity and human disease. Because we are a part of the environment and the top of many food chains, humans are exposed to many pollutants – constantly. We will, through the examination of several case studies, see how we have learned about pollution, toxicity, and human health. If you are interested in a medical career, consider taking courses in toxicology and even environmental toxicology. Diseases like cancer, heart disease, and Autism are at epidemic levels. Look at the prevalence (number of cases of disease per population over a specific time) of these diseases. For cancer, 5 in 100 people will be diagnosed with cancer by age 66, and this is an increasing trend since 1971. For heart disease, 6 in 100 people will have coronary heart disease over their lifetime. Autism is more alarming with 1 in 88 children born today being diagnosed with Autism; boys disproportionately affected at a rate of 1 in 54. Research scientists and medical clinicians are looking to understand the environmental factors that cause human disease. This is a growing and necessary field of study.