Rainwater's Pollution: A Natural Concern

Rainwater is considered polluted due to the presence of human-made chemicals called PFAS, which have now been found everywhere on Earth, from Antarctica to the Tibetan Plateau. PFAS, or poly- and perfluoroalkyl substances, are used in various products, from non-stick pans to waterproof clothing, and persist in the environment for years. While rainwater is essentially distilled, it is not lab-grade pure and can pick up pollutants during its journey through the air, including dust, sea spray, and smoke. This has led to concerns about the potential health risks associated with exposure to PFAS, including cancer, infertility, and immune system problems.

Rainwater is unsafe to drink due to 'forever chemicals'

Rainwater is unsafe to drink due to the presence of toxic chemicals called per- and polyfluoroalkyl substances, or PFAS, which are often referred to as 'forever chemicals'. PFAS are synthetic substances that do not easily degrade and are used in a variety of products, including non-stick pans, fire-fighting foam, water-repellent clothes, food packaging, and cosmetics. These chemicals have been found in rainwater samples across the globe, with levels that exceed what is considered safe for human consumption.

PFAS are toxic chemicals that accumulate in the body once ingested, potentially leading to a range of negative health problems. Research has linked PFAS exposure to an increased risk of liver cancer, decreased fertility, developmental delays in children, and various metabolic disorders. According to Dr. Perry Elizabeth Sheffield, associate professor in the Departments of Environmental Medicine and Public Health and Pediatrics at Mount Sinai, exposure to PFAS through drinking water has been associated with a higher risk of negative health outcomes.

The presence of PFAS in rainwater is a global concern, with studies finding contamination even in sparsely populated regions such as Antarctica and the Tibetan plateau. The levels of PFAS in rainwater often exceed what is considered safe and have been detected above US drinking water advisory levels and European safety levels. The Environmental Protection Agency in the United States has also announced new health advisories for PFAS, recognizing the potential health risks associated with these chemicals.

While rainwater may look clean, it can contain germs and chemicals that can make people sick. Bird droppings on roofs, for example, can contaminate rainwater barrels or tanks. It is recommended that people who collect rainwater for drinking, cooking, or bathing regularly test it for germs and chemicals and treat it to remove any contaminants. Granulated activated carbon filters and reverse osmosis filters are two types of filters that can be used to remove PFAS from drinking water.

The widespread contamination of rainwater by PFAS highlights the importance of taking action to reduce the use of these "forever chemicals" and protect human health. It also emphasizes the need for proper maintenance and testing of rainwater collection systems to ensure the water is safe for consumption.

Nonpoint source pollution

Rainwater pollution, or nonpoint source pollution (NPS), is caused by rainfall or snowmelt moving over and through the ground. As the runoff moves, it collects and carries natural and human-made pollutants, depositing them into lakes, rivers, wetlands, coastal waters, and groundwater. NPS pollution is distinct from pollution originating from industrial or sewage treatment plants, as it arises from numerous diffuse sources.

NPS pollution is primarily caused by land runoff, precipitation, atmospheric deposition, drainage, seepage, or hydrologic modification. The major sources of NPS pollution in Illinois, for example, are agriculture, urban runoff, and habitat modification. Urban runoff, flowing through storm drains and pipes, carries pollutants such as fertilizer, oil, pesticides, dirt, bacteria, and other toxins directly into streams, rivers, and lakes without undergoing treatment. Similarly, agricultural runoff from fields, livestock facilities, lawns, and gardens can contaminate water bodies with nutrients and sediments. Sediments, or eroded soil, can cause water to become cloudy, hindering aquatic organisms' ability to feed and reducing plant growth by blocking sunlight. Additionally, sediments can carry other harmful substances like metals and toxic chemicals.

To address NPS pollution, various programs and initiatives have been implemented. The US Environmental Protection Agency (EPA) offers fact sheets on nonpoint source control, including information on public involvement, coastal water protection, and managing agricultural impacts. The EPA also provides tips for preventing nonpoint source pollution, recognizing that nutrient pollution, caused by nutrients like nitrogen and phosphorus, is a costly and challenging environmental issue.

One effective strategy to combat NPS pollution is to soak up rainwater and reduce runoff. This can be achieved through the use of green infrastructure, such as green roofs and permeable pavements, which help to retain rainwater and minimize the amount of polluted water flowing into streets and water bodies. Implementing these measures not only helps to prevent water pollution but also reduces flooding, protects water resources, and enhances the aesthetics of neighborhoods.

Nutrient pollution

Rain is vital for life on Earth, but it can also be a source of pollution. One significant form of pollution transmitted by rainwater is nutrient pollution. This type of pollution occurs when excessive nutrients, particularly nitrogen and phosphorus, are introduced into aquatic ecosystems, causing adverse effects on water quality and the health of plants, animals, and humans that depend on these water bodies.

Polluted runoff

Rainwater, or runoff, is increasingly becoming a source of pollution. As cities and towns develop, forests and meadows are replaced by buildings and pavement. When it rains, the water runs off roofs and driveways into the streets. This runoff water collects a toxic mix of pollutants, including fertilizer, oil, pesticides, dirt, bacteria, and more, as it makes its way through storm drains and ditches to our streams, rivers, lakes, and oceans. This polluted runoff is one of the greatest threats to clean water, especially in the US.

Nonpoint source pollution, caused by rainfall or snowmelt, occurs when the runoff moves over and through the ground, picking up and carrying pollutants into nearby water bodies. Urban and suburban areas, with their extensive coverage of buildings, pavement, and compacted landscapes, are significant contributors to nonpoint source pollution. The increased runoff from these areas carries pollutants such as nitrogen and phosphorus into local waterways, causing nutrient pollution, which is a widespread and costly environmental challenge.

Agricultural runoff from farmland is another concern. As rainwater and snowmelt flow across fields, they pick up fertilizers, animal manure, and other contaminants, carrying them into rivers and streams. This type of polluted runoff is a primary source of pollution in many regions, and its effects are long-lasting. It erodes streams, kills fish, pollutes drinking water sources and swimming areas, and contributes to flooding.

To address the issue of polluted runoff, creating "green infrastructure" in urban and suburban areas is a promising solution. This involves implementing strategies to slow down and soak up the polluted runoff. Some examples include planting rain gardens and native plants in low-lying areas, using permeable pavements, and attaching downspouts to rain barrels to collect rainwater for later use. These measures help keep rainwater closer to where it falls, reducing the amount of polluted runoff flowing into streets and local water bodies.

By taking action to soak up the rain and reduce runoff, communities can not only prevent water pollution and protect their drinking water sources but also reduce flooding, beautify neighbourhoods, and lower costs associated with water management.

PFAS chemicals in rainwater

PFAS, or poly- and perfluoroalkyl substances, are synthetic compounds that have been used in a variety of industrial and consumer products since the 1950s. These include non-stick pans, fire-fighting foam, water-repellent clothing, food packaging, and even products like Scotchgard and Teflon. PFAS are often referred to as "forever chemicals" because they can persist in the environment for years, and have now been detected in rainwater worldwide.

A 2022 study published in the journal Environmental Science & Technology found PFAS levels in rainwater that greatly exceeded safe drinking water guidelines, particularly in the US. This is concerning because rainwater is a source of drinking water for many communities, and the presence of PFAS in rainwater indicates the widespread nature of PFAS pollution. The study's authors from Stockholm University urge the rapid restriction of PFAS use due to potential health risks, including cancer, infertility, and developmental issues in children.

PFAS contamination in groundwater was first reported in 2001, and while some PFAS variants like PFOS and PFOA have been phased out of manufacturing in the US, they continue to be detected in rainwater years later. Researchers at the University of Wisconsin and the National Atmospheric Deposition Program (NADP) collected rainwater samples in 2019, finding PFAS in all of them. This suggests that PFAS pollution is not only widespread but also persistent in the environment.

The Integrated Atmospheric Deposition Network (IADN), a monitoring program for the Great Lakes, has also detected high levels of PFAS in precipitation (snow and rain) across the region. The lead author of an April 2021 study, Kyndalanne Pike, expressed surprise at the high levels of PFOS and PFOA found in rainwater years after they were no longer manufactured in the US. While the health effects of PFAS exposure are still being studied, the potential impact on human health is a significant concern, especially considering PFAS's presence in all major US water supplies.

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