Study shows worldwide rainwater is too polluted for human consumption

It is no longer news that human activity has severely polluted rivers, oceans, and other bodies of water. But according to a recent study, even rainfall from all across the world may be contaminated with "per- and polyfluoroalkyl compounds," making it unsafe to drink.

PFAs are dangerous compounds created by humans that are widely dispersed in the atmosphere. Fluoropolymer coatings made with them can withstand heat, oil, stains, grease, and water. Clothing, furniture, adhesives, food packaging, non-stick cooking surfaces, and electrical wire insulation are examples of products that employ PFAs.

Due to their widespread distribution, they contaminate even the most isolated areas of Earth. The maximum allowable guideline values for PFAs in water have significantly dropped over the past 20 years as a result of increased knowledge about the toxicity of these compounds. This indicates that PFA concentrations in rainwater are higher than these recommended values all over the world, according to a report that was published in Environmental Science and Technology. The study examined the concentrations of four PFAs in diverse global environmental media, such as rainwater, soils, and surface waters: perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), and perfluorononanoic acid (PFNA), the Indian Express reported.

Although studies that collected rainwater samples in India are not included in the research, Ian Cousins, the study's primary author, told indianexpress.com that a similar conclusion may be made about the country's rainwater.

"As we see, rainwater levels worldwide are similar. I think the study can be extrapolated to India. PFAs are globally used and spread," said Cousins, in an email interaction.

PFA exposure has been linked to several health risks, including reduced fertility, effects on children's development, interference with body hormones, elevated cholesterol levels, and an increased risk of certain cancers, such as prostate, kidney, and testicular cancer, according to the United States Environmental Protection Agency.

"Our knowledge of the toxicity of PFAS has increased over time. Recent research on immunotoxicity has driven the drinking water regulations even lower than before. Long-term low-level exposure to certain PFAS may make it more difficult for humans to build antibodies after being vaccinated again various diseases," he added.

In a nation like India, where rainwater collection has a long history, this situation is particularly troubling. In fact, mandates for rainwater gathering have been issued in several areas of the nation. For instance, the Tamil Nadu government mandated the installation of state-approved rainwater harvesting systems on the premises of all governmental, commercial, educational, and residential buildings. According to a recent study, the country's captured rainwater could not be suitable for human consumption.

"There are fairly simple clean-up methods for removing PFAS such as filtering with activated carbon, but to clean the water to the very low levels in the guidelines is challenging and expensive. The activated carbon will need to be renewed regularly and the old contaminated material destroyed," explained Cousins

While the need for pricey filtration techniques for rainwater is alarming in and of itself, there is a much deeper issue. PFAs were once widely thought to eventually wash off into the oceans where they would be diluted. However, according to the findings of a separate recent study, some PFAs can be returned to the atmosphere by mixing with sea spray aerosols. This could imply that PFAs are continuously cycled through the hydrosphere, resulting in their continued contamination of surface soils, freshwater bodies, and precipitation.