A National Institutes of Health working group has highlighted 11 key categories of diseases and other health consequences that are occurring, or are expected to occur soon, due to climate change.
In a new report, A Human Health Perspective on Climate Change, the group said that environmental consequences of climate change—such as sea level rise, changes in precipitation resulting in flooding and drought, heat waves, more intense hurricanes and storms, and degraded air quality—will affect human health both directly and indirectly and the way their healthcare is provided.
The study "articulates, in a concrete way, that human beings are vulnerable in many ways to the health effects of climate change," said Linda Birnbaum, PhD, director of NIH's National Institute of Environmental Health Sciences (NIEHS) and the National Toxicology Program, whose institute led the interagency effort. "It lays out both what we know and what we need to know about these effects in a way that will allow the health research community to bring its collective knowledge to bear on solving these problems."
The study highlights the state of the science on the human health consequences of climate change on:
Asthma, respiratory allergies. Climate change will affect air quality through several pathways including aeroallergens such as pollen and mold spores and increases in regional ambient concentrations of ozone, fine particles, and dust. Some of these pollutants can directly cause respiratory disease or exacerbate respiratory disease in susceptible individuals.
Mental health and stress related disorders. Many mental health disorders can also lead to other chronic diseases and even death. Stress related disorders derive from abnormal responses to acute or prolonged anxiety, and include diseases such as obsessive compulsive disorder and post traumatic stress disorder.
Cancer. One possible direct impact of climate change on cancer may be through increases in exposure to toxic chemicals that are known or suspected to cause cancer following heavy rainfall. In the case of heavy rainfall or flooding, there may be an increase in leaching of toxic chemicals and heavy metals from storage sites and increased contamination of water with runoff containing persistent chemicals that are already in the environment.
Neurological diseases and disorders. Onset of diseases such as Alzheimer’s and Parkinson Disease are occurring at earlier ages across the population, the study noted. Environmental factors are suspected of playing a large role in both the onset and severity of these conditions—although there is a gap in our understanding of this role.
Cardiovascular disease and stroke. Cardiovascular mortality associated with heat has been declining over time—presumably the result of increased air conditioning use. However, mortality associated with extreme cold has remained constant. Cardiovascular hospital admissions increase with heat.
Waterborne diseases. A recent shift has been seen in waterborne disease outbreaks from gastrointestinal toward respiratory infections such as that caused by Legionella, which lives in cooling ponds and is transmitted through air conditioning systems. In addition to diarrheal disease, waterborne pathogens are implicated in other illnesses with immunologic, neurologic, hematologic, metabolic, pulmonary, ocular, renal and nutritional complications.
Foodborne diseases and nutrition. Drought has been shown to encourage crop pests such as aphids, locusts, and whiteflies, as well as the spread of the mold Aspergillus flavus that produces aflatoxin, a substance that may contribute to the development of liver cancer in people who eat contaminated corn and nuts.
Weather related morbidity and mortality. A changing climate, coupled with changing demographics, is expected to magnify the already significant adverse effects of extreme weather on public health. For example, the intensity and frequency of precipitation events in the United States have increased over the past 100 years in many locations.
Heat related morbidity and mortality. Factors such as age and the burden of other serious illnesses such as heart disease and diabetes that might exacerbate heat related problems are critical. In the U.S., the number of individuals 65 years of age and older—who are more susceptible to heat effects—is expected to increase from 12.4% in 2000 to 20% in 2060.
Vectorborne and zoonotic diseases. This includes diseases, such as malaria, which can be transmitted from animals to humans. A "severe degradation" of rural and urban climate and sanitation conditions could bring malaria, epidemic typhus, plague, and yellow fever "to their former prominence."
Human developmental effects. The environment can be a "potent modifier" of normal development and behavior, according to the report. Environmental effects on development include subtle changes such as small reductions in IQ from exposure to lead, changes in onset of puberty from exposure to endocrine disrupting chemicals, and birth defects such as cleft palate due to dioxin like compounds.
Janice Simmons is a senior editor and Washington, DC, correspondent for HealthLeaders Media Online. She can be reached at jsimmons@healthleadersmedia.com.