Thousands of Mysterious Yellow “Sponges” Wash Up On French Beaches

Though experts were initially stumped, the substance has now been identified

Sea-Mer Association

France’s Opal Coast is studded with pristine, sandy beaches that overlook the deep blue waters of the English Channel. But over the past week, this picturesque stretch of land was marred by yellow, spongy clumps that washed ashore in droves. 

The weird, fluffy balls numbered in the hundreds of thousands, affecting several beaches along the coast—including La Slack, Wimereux, Le Portel, Equihen-Plage, Hardelot, Le Touquet, Stella and Berck. Experts were initially befuddled at the cause, but the strange substances have now been identified, according to the CBC.

As Gizmodo’s George Dvorksy reports, a team of firefighters was tasked with collecting samples of the invasive clumps earlier this week. The materials were analyzed at the Cedre Association, which specializes in testing hydrocarbon pollution. The results of the test suggest that the “sponges” are actually paraffin wax, a derivative of petroleum, coal or oil shale.

Paraffin wax is used in the manufacture of many products, including candles, crayons, and food additives. According to Tia Ghose of Live Science, the substance is “often transported in large quantities by tanker ships, and because it floats, will rise to the top of the water and wash ashore in clumps.”

The English Channel is a highly trafficked area, and one of the many ships that pass through its waters may be responsible for the spongy blobs invading the shores of France.

 Jonathan Hénicart, president of the environmental NGO Sea-Mer Association, told the CBC that ships are allowed to dump paraffin wax residue into the sea—in limited quantities and far away from the shore.  But the huge amount of the yellow fluff leads Hénicart to believe that somebody emptied the residue close to land. 

It isn’t the first time that globs of paraffin have invaded the coast of a European country. In May of this year, the waxy substance washed up onto the beaches of North Yorkshire, England.

The Cedre Association told the French publication Le Voix du Nord that paraffin "does not present a danger to public health or fauna and flora,” according to the CBC. But Sea-Mer notes on its website that the substance could be “very polluting and  harmful to the environment” if it contains chlorine or polycyclic aromatic hydrocarbons

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