The Human Health Costs of Environmental Degradation

We’ve talked about how land management practices can affect long-term profits off the land, but profits aren’t the only thing at stake. Land management directly affects how ecological functions help or harm human health. Effects on human health can be as obvious as how pollution affects the lungs or as convoluted as how forest cover affects malaria. This is best illustrated with examples.Photo by Risa Pesapane in Uganda: deforestation and erosion.Children in Uganda pose before deforested hills with erosion problems. Photo courtesy of Risa Pesapane.

A study from 2013 reviews case studies of what we’ve discovered about how ecosystem changes affect human health, as well as the limitations of what we can know currently. We’ve cross-referenced each case for validity.

The study mentions how:

  • Dams and irrigation projects can significantly increase the prevalence of schistosomiasis and malaria in parts of Africa and South Asia.
  • Deforestation increases exposure to malaria in Africa.
  • Deforestation in Africa also alters the composition and density of aquatic snail species so that schistosomiasis is more easily transmitted.
  • Agricultural runoff of nitrogen and phosphorus in Belize causes a change in the vegetation of downstream wetlands that breeds a more efficient malaria vector than the less efficient vector. This leads to increased malaria exposure in coastal settlements.
  • As bird diversity decreases in the U.S., the risk of West Nile virus exposure rises.
  • As mammal diversity decreases in the U.S., the risk of Lyme disease exposure rises. Here’s why.
  • Loss of species diversity can mean a loss of potential sources of pharmaceuticals and models for studying disease.
  • Loss of pollinators could be problematic in that 35% of the human diet relies on pollinated crops.
  • Climate change is expected to increase exposure to air pollution, respiratory allergens, infectious disease, natural disasters, water scarcity, food scarcity, and population displacement.

    “Allergenic plants grown at elevated carbon dioxide produce more pollen over a longer pollen season than those grown at ambient levels.” –Myers, et al.

Photo by Risa Pesapane in Uganda- deforestation and erosion.

Deforestation and erosion in Uganda. Photographed by Risa Pesapane.

Human health impacts don’t have to be negative, however. Some changes in local ecosystems can produce positive human health outcomes. For example, malaria was reduced in the Tennessee Valley and in Nigeria by draining swamps where known malarial vectors dwelt. Unfortunately, draining swamps means the loss of the water filtration services they provide.

Another complication is that some ecosystem changes can produce benefits for some human populations while harming others.

“Over the course of economic development, people replace complex, natural systems with engineered infrastructure and markets as the source of food, water purification, shelter, fuel, clothing, and protection from natural hazards and infectious disease. A majority of people are able to make this transition and reap the benefits… However, the poorest and least entitled may fail to make the transition successfully, unable to access either the engineered infrastructure or markets (Fig.2). They are left with degraded natural systems but little with which to replace them.” –Myers, et al.

These are only a few examples of known connections between ecosystem changes and impacts on human health. It’s clear from these cases that there is a link between human health and the state of natural systems, but there are some limitations to what specifically we can conclude about human-ecosystem health interactions.

Current research focuses on only one health outcome at a time, rather than how ecosystem changes affect different aspects of human health. Furthermore, if there is a clear human health problem in an area, it can be difficult to pinpoint exactly what caused the health repercussion.

Some parts of the world are better prepared to deal with environmental changes than others. If radishes ceased to grow well in parts of the U.S., gardeners would plant other crops and/or go to the grocery store. In Uganda, people are starving because of a blight on their cassava staple. Unfortunately, the poorest people on Earth are usually the most harshly affected by changes in ecosystem function.

Lastly, it is much more difficult to quantify the benefits of an ecosystem intact or what is lost when they are changed of destroyed. It is much easier to quantify risk for certain diseases or disasters. Despite the clear and vital connection between human health and ecosystem functions, we tend to overlook or undervalue them until they are gone.

More research is needed to try to overcome some of these limitations and difficulties. Even with the limited research we have, however, it is clear that the health of humans is still tied to the complex interactions of natural systems. More than ever it is urgent that land managers take a systems approach to management. Every action has its consequence, and it’s time we learn what land use means for human health.

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About Laurel Sindewald

Laurel is an alumna of Warren Wilson College with a BS in Conservation Biology and a BA in Philosophy. She is a writer for Rural System, Inc.

Comments

  1. Excellent analysis, Laurel. I like to think of an end-of-year analysis of the rural land-owner’s status and think of “net” annual family returns. I’m pondering the wager that Rural System’s work will produce more such gains by working with Laurel’s findings and with safety, first aid, quick attention to symptoms, and preventing disease (at least stopping smoking, cleanliness, and reducing weight) than with increasing crop, forest, and livestock production. “Tightly managed net annual financial gain for the long-run” has to be the winner.

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