Swimming in lakes, rivers and the ocean has long been a popular way to cool off as well as to get a great low impact workout. We all have fond memories of cooling off during the summer months by plunging into the water, or that great workout where you set a personal record swimming around the local lake. However, a question not often considered is how that plunge might negatively affect your health. Moreover, how might prolonged periods of exposure and possible ingestion of this water, as might occur during an athlete’s swimming workout or race, impact any potential health risk?
Water quality standards
Water quality standards are created by the U.S. Environmental Protection Agency (EPA) for different types of water bodies and are based on the intended uses of this water. In the United States, each state is required to submit a set of biannual reports on the quality of the water in their area. The primary uses when considering water quality are: drinking water, safety of human contact (i.e. swimming), and the overall health and sustainability of the ecosystem. Different water uses warrant different concerns and therefore separate standards have been established for what is considered polluted vs. un-polluted. Environmental scientists are working to understand the function of these waters within specific ecosystems as well as how human and other species affect the system. Lastly, they are working to determine the sources and fates of contaminants in the environment, many of which may end up in local waterways(1).
Causes of water pollution
Water quality is a very complex subject, in part because water is a multifaceted component of our world, which is intimately connected to the ecosystem in which it resides. Major causes of water pollution include:
- Industrial sources including toxins and chemicals
- Runoff from agricultural areas
- Urban and suburban storm water runoff
- Discharge of untreated sewage
Water quality and how our health can be affected is a very broad topic; however, for the purpose of this article the focus will be on the health impacts and water quality issues as they pertain to water for athletic and recreational use, specifically swimming.
Urban and industrial development, farming, mining, combustion of fossil fuels, stream-channel alteration, animal-feeding operations, and other human activities can change the quality of natural waters. For example, fertilizers that are applied to crops and lawns can be dissolved easily in rainwater or snowmelt runoff. Excess nutrients carried into streams and lakes encourage abundant growth of algae, which leads to low oxygen in the water and disruption of the natural ecology, potentially allowing harmful bacteria, viruses and parasites to inhabit waters, as well as simply making it less desirable for recreation(2).
After decades of use, pesticides are now ubiquitous in streams and ground water, though they rarely exceed the existing standards and guidelines established to protect human health. Some pesticides have not been used for 20 to 30 years, but they are still detected in fish and stream bed sediment at levels that may pose a potential risk to human health, aquatic life, and fish-eating wildlife. There are so many chemicals that have been or are in use that determining the level in our water ways, as well as any risk to human health and aquatic life, is a complex task(2).
The EPA estimates that every year, in each individual county across the United States, the amount of untreated sewage that enters the environment is enough to fill both the Empire State Building and Madison Square Garden(5). Raw sewage is supposed to be carried to wastewater treatment plants for processing. Yet sewage collection systems, 200 years old in some places, are plagued by broken, leaking or overloaded pipes that allow untreated sewage to be released directly into the environment(9). Additionally, during periods of wet weather, rainwater can seep into corroded pipes, causing the sewage treatment facilities and system to become overloaded. This results in sewage backups and overflows, and the result is that raw sewage finds its way into bodies of water. Some older water treatment systems are actually designed to carry both sewage and storm water run off, so during heavy rains, sewage automatically bypasses treatment facilities and is diverted directly into the waterways. This problem is being compounded by growing populations and more severe storms(9).
Conflicting evidence
There are still many questions yet unanswered about the health effects of swimming in polluted water. There is general consensus that a health risk is present, and many experts agree that human fecal material from raw sewage is the most widespread and common cause of these risks and must be addressed(11).
Several studies conducted by the EPA, US Geologic Survey (USGS) and Centers of Disease Control (CDC) have established a health-based relationship between indicators of water fecal contamination and swimming associated illness(6, 7). However, it seems that for the amount of sewage that enters the water ways, relatively few people get sick(14). There is conflicting evidence on the link between illness and fecal-contaminated water. Some studies show there is not a proportionate rise in illness with a rise in fecal contaminates(8). However, some experts estimate that between 1.8 and 3.5 million illnesses are caused by swimming in sewage contaminated waters(9), but these cases are greatly under reported due to minimal symptoms, lack of public awareness and poor public records. While existing data is inadequate in showing exactly how many people get sick every year, there does seem to be strong evidence suggesting a link(10, 11).
The decision to close waters for recreational use due to potentially harmful pollutants can be very difficult. There is poor understanding and general acceptance of what is considered safe, and local atmospheric and water conditions can create additional difficulties as well. Indicator organism concentrations can vary from minute to minute at a given beach, based on events such as changes in wastewater treatment, weather patterns, strength or magnitude of rainfall, tidal cycles, and UV strength. Of particular concern are the short term (minute to hour) variability and water source mixing which can lead to "moving hot spots of microorganisms."(7) Additional research is needed to understand these processes and develop monitoring protocols that will allow for adequate characterization of microbial water quality(7).
Illnesses associated with water pollution
Although there are many potential symptoms a swimmer may experience, gastrointestinal illness is the most common, and was found to be significantly associated with water fecal contamination in some studies(3). Other cases of public illness and larger outbreaks have been linked to Giardia and cryptosporidium pathogens that were discovered in public waters(4). Often the presence of E. coli and enterococci provides an indication of the level of pollution. Yet there is little consensus between different local, state and national agencies on levels that are regarded as safe(14) and it leaves athletes and recreational swimmers with little information or choices.
Viral Gastroenteritis is the most common illness associated with swimming in polluted water(3). Although the symptoms are usually minor, they may present in a variety of forms that can include one or more of the following:
- Chills
- Nausea
- Diarrhea
- Stomachache
- Headache
- Fever(12)
Other minor illnesses can result from swimming in polluted water including diseases affecting the eye, ear, skin, and upper respiratory infections. In highly polluted water swimmers may be exposed to more serious diseases like Amoebic dysentery, Cholera, Giardia, Hepatitis, Intestinal parasites, Norwalk Virus, Shigellosis, and Viral Respiratory Infections. Small children, infants, the elderly, and those with compromised immune systems are most likely to develop illnesses or infection after swimming in polluted water(13).
Determining if your recreational water is polluted
How can an athlete determine if their favorite training or race waterway is polluted, or if it is likely to become polluted after a rainstorm or with other seasonal changes? Unfortunately, there is not one comprehensive source that tracks sewage pollution. Some are calling for the federal government to establish a national sewage inventory to track and inform people about the release of untreated or under-treated sewage into open waterways. Here are some websites to check out:
- Beach water quality and beach closings http://www.epa.gov/waterscience/beaches
- Compliance records of sewage treatment plants in your area http://www.epa.gov/echo
- Lakes and rivers in your area that are polluted with sewage http://www.epa.gov/waters
- Waterborne disease outbreaks (including the source of the outbreak) http://www.cdc.gov/mmwr
Depending on the policy of local officials and water treatment facilities, the public may be notified when local sewage systems back up or overflow; however, beaches are not required to be closed unless sewage has been shown to reach beach water by measuring surrogate organisms.
Guidelines for athletes
To avoid polluted water during your swim workouts and lessen your risk of negative health effects, observe the following guidelines from the department of health:
- Be aware of advisories and closures and avoid swimming in those areas.
- Do not swim or allow children to play in storm drains/storm water (visible runoff). Avoid swimming during and after rainfall.
- Avoid submerging your head and ingesting water, which may be difficult if an athlete is trying to get in a training session.
- Avoid swimming if you have an open wound or infection.
Swimming in open waterways is a great form of recreation as well as exercise. However, very little is known and there is no consensus on what the health risks are of such activities. Even in seemingly clear, pristine lakes, rivers and oceans there may be a risk. However, the majority of swimmers will not experience any major illness due to recreating in polluted waters. The bottom line is, as environmentalists, health professionals and the EPA continue to research water quality and human health, when you engage in open water swims, you should follow the above guidelines in order to minimize any potential health risks.
(1) Environmental Protection Agency, Summary of the Clean Water Act, http://www.epa.gov/lawsregs/laws/cwa.html, accessed June 3, 2008.
(2) United States Geologic Survey, http://pubs.usgs.gov/fs/fs-027-01/index.html, accessed June 3, 2008.
(3) Wade, T.J., R.L. Calderon, E. Sams, M. Beach, K.P. Brenner, A.H. Williams, and A.P. Dufour, 2006. Rapidly Measured Indicators of Recreational Water Quality are Predictive of Swimming, Associated Gastrointestinal Illness. Environmental Health Perspect
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