A new study shows the law of unintended consequences may have reared its ugly head in the decades following the 1987 Montreal Protocol that successfully saved the ozone layer.
The Montreal Protocol, an international treaty ratified by 197 parties, was designed to phase out ozone-depleting chlorofluorocarbons (CFCs), such as freon used in old air conditions. And it’s working—the ozone hole in Antarctica is recovering. However, new research suggests the chemical compounds that replaced CFCs are not a better alternative. In fact, they degrade into products that do not break down in the environment and have instead continually increased in the Arctic since 1990.
“Our results suggest that global regulation and replacement of other environmentally harmful chemicals contributed to the increase of these compounds in the Arctic, illustrating that regulations can have important unanticipated consequences,” said Cora Young, professor at York University, and the paper's corresponding author.
Short-chain perfluoroalkyl carboxylic acids (scPFCAs)—part of the perfluoroalkyl substances (PFAS) class of man-made chemicals—have replaced CFCs in automotive, electrical, industrial and construction applications. For the study, researchers from York University and Environment and Climate Change Canada sampled ice cores from two locations in the Canadian Arctic looking for three compounds of scPFCAs: trifluoroacetic acid (TFA), perfluoropropionic acid (PFPrA) and perfluorobutanoic acid (PFBA).
According to the results, since 1990, all three compounds have steadily increased in the Arctic. Concentrations of TFA were the highest, above the method detection limit in every sample from Devon Ice Cap and 96 percent of Mt. Oxford samples. Although slightly lower than TFA, concentrations of PFPrA were also above the detection limit in every sample from the two ice cores. Conversely, concentrations of PFBA were much lower and not detected in all samples. PFBA was detected in 68 percent of samples from the Devon Ice Cap and 74 percent of samples from the Mt. Oxford icefield.
Measurements made throughout the 1980s confirmed scPFCAs were consistently detected at low levels in both ice core locations. However, researchers found TFA rose almost an order of magnitude between pre‐1990 and post‐2000. Similar increases were observed for PFPrA and PFBA over the same time period.
The researchers say this is troubling as these compounds have already been found accumulating in human blood at an exceedingly high level. They have multiple pathways of human exposure, as accumulation has been demonstrated in crops for human consumption and aqueous environments, including lakes, rivers and wetlands. Additionally, current water treatment technology is unable to remove scPFCAs.
“For these reasons and more, persistence and mobility should be taken into consideration when replacing one class of performance chemicals with another, since this can often lead to unanticipated environmental effects that persist for the foreseeable future,” reads the paper, published in Geophysical Research Letters. “The Montreal Protocol will undoubtedly continue to positively impact stratospheric ozone and climate and represents an unparalleled achievement in global environmental stewardship. However, this study emphasizes that even the most successful regulations can result in unintended environmental impacts.”
Photo: Researchers drill and measure ice cores in the Actic. Credit: University of Alberta