Is it safe to drink rainwater? | | Live Science
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If you stick your tongue out in the rain, you might think that the drops you drink are the same as the water that comes out of the faucet. However, rainwater actually contains many microscopic elements that are filtered before being pumped into your home.
Is it safe to collect and drink rainwater?
There are many contaminants that rainwater can contain. bacteria, virusaccording to parasites, dust, smoke particles, and other chemicals, Centers for Disease Control and Prevention (opens in new tab) (CDC). Collecting rainwater from roofs can contain animal droppings such as bird droppings, and older roofs and drains can contain asbestos, lead, copper It may even enter the tank. When rainwater collects in open containers, it can also become filled with decaying organic matter such as insects and dead leaves. For these reasons, the CDC does not recommend collecting and drinking rainwater, but recommends using it for other purposes, such as watering plants.
However, levels of these contaminants can vary greatly depending on where you live, and your risk of disease is highly dependent on the amount of rainwater you drink. Having a clean collection system and properly sterilizing rainwater with chemicals or boiling can remove most impurities. This has caused a lot of confusion about whether rainwater is unsafe to drink.
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But now, in the modern age of man-made chemicals, there are new risks associated with drinking rainwater. A study published in the journal August 2022 found that environmental science and technology (opens in new tab)researchers found that rainwater around the world has concentrations of toxic substances PFAS (per- and polyfluorinated alkyl substances) Exceeds health guidelines. These findings mean that drinking rainwater is definitely dangerous, especially if it’s untreated.
What are PFASs?
PFAS is a collective name for over 1,400 man-made chemicals and substances that have historically been used in a wide variety of products, including textiles, fire foam, nonstick cookware, food packaging, artificial turf, and guitar strings. An environmental chemist at Stockholm University in Sweden told his Live Science in an email.
However, “our current understanding of biological effects is largely based on studies of four perfluoroalkyl acids (PFAAs), a subgroup of PFASs,” Cousins said. These his PFAAs include perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), and perfluorononanoic acid (PFNA), which are the main focus of research. included.
Past research has shown that these chemicals are highly toxic and can cause a wide variety of problems, including many types of problems. cancer,infertility, pregnancy complications, developmental disorders, immune system intestinal conditions, and various diseases, liver Cousins said not only could vaccines become less effective in children, but so would the thyroid gland. PFAS could also cause further damage to the environment, but this idea has not been studied in great detail, he added.
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This evidence has led to PFAAs and most other PFASs being banned or severely restricted within the last 20 to 30 years. Health guidelines on PFAS have also been readjusted to reflect the chemical’s toxicity. For example, in the United States, the safe level of exposure to PFOA as determined by the Environmental Protection Agency (EPA) is 37.5 million times lower than before. Researcher statement (opens in new tab).
PFAS doesn’t break down very easily, so it remains in the environment for a long time after it’s produced, and it’s toxic as well, Cousins said. This has led scientists to call his PFAS “the eternal chemical,” he added.
polluted rainwater
In this study, researchers collected data from rainwater samples collected around the world and found that PFAS are still abundant in rainwater around the world. earth At concentrations that exceed safety guidelines set by the EPA and similar regulatory bodies in other countries.
Experts had hoped that PFAS levels would have started to decline by now, but that’s clearly not the case, Cousins said. He added that he thinks it represents the boundaries of the planet, a conceptual limit beyond which something becomes unsafe for humans, and that we have already exceeded it.
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The most striking finding was that PFOA levels in rainwater were at least 10 times above EPA safe levels at all sampled locations around the globe, including the Tibetan Plateau and Antarctica.
Researchers still don’t know exactly how PFAS is transported to the farthest corners of the planet, Cousins said. The team hypothesizes that his PFAS at sea level are reinjected into the atmosphere by sea spray and then transported to other areas, where they fall as rain. They plan to test this hypothesis in future studies. It’s also possible that PFAS is still leaking into the environment from landfills, he added.
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It is too early to predict the overall public health impact of PFAS-rich stormwater worldwide, but it may already be underway. “Over the last 20 to 30 years, we’ve been exposed to even higher levels,” Cousins said. “We now better understand the potential consequences of that exposure.”
Cousins said the impact of PFAS could be greater in developing countries, where millions of people rely on rainwater as their only source of drinking water. But even in certain parts of the developed world, such as Western Australia, drinking rainwater is surprisingly common, he added.
Even if stormwater is properly treated, there is still no guarantee that PFAS will be removed. PFAS are also found at low levels in drinking water from taps and bottles, although often at safe levels.
PFAS levels eventually decrease as they circulate into deeper waters, a gradual process that takes decades, Cousins said.
Originally published in Live Science.
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