Fewer Toxic Chemicals Are Showing Up in the Himalayas, and That’s Good News for Your Health

Scientists find that the bans on some once widely used carcinogens are paying off.

(Photo: Tim Chong/Reuters)

Mar 13, 2015· 1 MIN READ
Padma Nagappan is a multimedia journalist who writes about the environment, renewable energy, sustainability, agriculture, and biotechnology.

Chemicals used in nonstick cooking pans, fire-retardant foam, and other common consumer products travel thousands of miles to reach such remote corners of the world as the Tibetan Himalayas.

But the good news is that the volume of chemicals showing up in ice cores on the mountains’ western slope is on the decline. That shows that Western countries’ moves to ban or phase out the chemicals is working, according to new research.

“Ice cores in places like Tibet are barometers for global pollution,” said Crispin Halsall, environmental chemistry professor at the University of Lancaster and one of the senior authors of the ice core study with the Institute of Tibetan Plateau Research. “When legislation bans certain chemicals, we don’t detect them in the latent snow core. It’s there in the core for the 1990s, but it’s not there for the later years.”

That was not the case for the eastern slope, however. Deposits of the chemicals deposited from Asia have grown with the region’s industrialization. The good news is that those chemicals are less toxic than the ones used in the West in decades past.

The scientists spent five months collecting Tibetan ice core samples and testing them for the chemical perfluoroalkyl.

Why that particular chemical?

“It’s commonly used in huge quantities, it gets in the environment, and it doesn’t break down,” Halsall said. “It reaches remote regions like Tibet and the Arctic as well as the marine environment. Some of the chemicals also bioaccumulate in breast milk and in our blood.”

Why test ice cores?

Ice cores make for better samples than testing the air, because chemicals accumulate over time in ice and the dates of deposit can be pinpointed. It’s also cheaper and easier to test ice cores because scientists can collect years’ worth of samples during a single expedition.

“Some of the highest concentrations on the east [slope] are in the most recent, fresh snow fall,” Halsall pointed out. “It was dominated by shorter-chain chemicals, which are more typical of production practices in Asia.”

Shorter-chain chemicals don’t bioaccumulate the same way longer chain chemicals do, so they’re less toxic, he said.

The United Nations Stockholm Convention on persistent organic pollutants has played a role in reducing the use of the most toxic chemicals linked to cancer, birth defects, and damage to the immune, reproductive, and nervous systems.

“But much of the change and restriction in use has been through good stewardship from leading companies like 3M and Dupont, because of how harmful they are,” Halsall said. “Some in the industry have also woken up to the mistakes in using certain harmful chemicals.”