Pollution also comes from above. Dangerous levels of man-made PFAS have been found in rain around the world and are linked to cancer , behavior and learning problems in children, increased cholesterol, impaired immunity, and infertility and pregnancy complications, among other serious health problems. Health.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS ), which are believed to enter the environment through industrial emissions, wastewater, or packaging transfer, have many uses, including in fire-fighting foams, nonstick coatings on pans, and textiles.

rain from the sky

These PFAS are highly persistent man-made hazardous chemicals that are currently dispersed in the atmosphere globally and can be found in rainwater and snow even in the most remote places on our planet. Many can take more than 1,000 years to degrade.

The US Environmental Protection Agency (EPA) now recommends a safe concentration of PFOA of 0.004 nanograms per liter (ng/L); the EU Environmental Quality Standards say PFOS should be 0.65 ng/L, while the US EPA suggests 0.020 ng/L for PFOS; and the Danish drinking water guideline for four PFAAs (PFOA + PFNA + PFHxS + PFOS) is 2 ng/L.

“There has been a staggering decline in the reference values for PFAS in drinking water over the last 20 years. For example, the drinking water guideline value for a well-known substance in the PFAS class, namely perfluorooctanoic acid (PFOA), which causes cancer, has decreased 37.5 million times in the US.” commented Ian Cousins, professor of environmental sciences in Stockholm and lead author of the study published in the journal Environmental Science & Technology.

Alert

However, the study led by Stockholm University and ETH Zurich shows that current levels of PFAS in environmental media are now above reference levels , defining a new planetary limit for novel entities that has been exceeded.

“Under the latest US guidelines for PFAS in drinking water, rainwater everywhere would be considered unsafe to drink. Although we don’t often drink rainwater in the industrial world, many people around the world hope that safe to drink and supplies many of our drinking water sources,” continues Cousins.

These findings have led scientists to conclude that a ‘planetary boundary’ has been crossed: there is no place on Earth where one can avoid substances. The researchers therefore suggest that PFAS use and releases be ‘rapidly reduced’, as the chemicals have little reversibility.

Conducting laboratory and field work on the atmospheric occurrence and transport of PFAS over the last decade, Professor Cousins ​​and colleagues found that atmospheric levels of some of these chemicals are not markedly declining, despite several major manufacturers are phasing them out. In addition to being highly persistent, their continued presence in the atmosphere is also due to natural processes that continually recycle them back into the atmosphere from the surface environment, such as the transport of seawater into the sea air by marine aerosols.

“So now, due to the global spread of PFAS, environmental media everywhere will exceed environmental quality guidelines designed to protect human health, and we can do very little to reduce PFAS contamination. In other words, it makes sense to define a planetary limit specifically for PFAS and, as we conclude in the paper, this limit has now been exceeded,” the authors conclude.

Referencia: Per- and polyfluoroalkyl substances (PFAS) define a new planetary boundary for novel entities that has been exceeded, Environmental Science & Technology (2022). DOI: 10.1021/acs.est.2c02765