- January 15, 2025
- More articles By Chris Carroll
- Illustrations by Valerie Morgan
We’re a salty bunch.
From birth to death, the average American consumes nearly 14 tons of sodium chloride, or table salt, a number that just scratches the surface of the volume of “salts,” broadly speaking, that society uses, says geology Professor Sujay Kaushal. His research shows how humans are making the Earth’s surface saltier by digging up increasing volumes of these minerals.
“Salts of various kinds are used in agriculture, in construction materials—places people don’t necessarily expect,” he says. “The problem is that they hit these thresholds in the environment where they’re hurting aquatic ecosystems, and also affecting human health.”
Just like in our diets, some of this salt is necessary, but Kaushal—who’s called for better management to limit damage—has a few suggestions for cutting back.
CHEMICAL FERTILIZERS
Growing food, not to mention beautiful surburban lawns, frequently involves spreading fertilizers that contain chloride and other salts that leach into waterways. Sparing application and not applying right before heavy rain is forecasted can minimize the harm.
FOOD
Table salt flushed away as a component of human waste creates a measurable impact on the environment, because sewage treatment plants can’t remove salts. This essentially unavoidable effect of staying alive highlights the need to minimize other sources of environmental salts, Kaushal says.
CLEANING PRODUCTS
Sodium borate, or borax, is one of many common salts used in detergents and cleaning products. These run down our drains and degrade water quality, and the more we skimp—possibly by substituting non-salty alternatives like vinegar or rubbing alcohol—the better.
BUILDING MATERIALS
Calcium salts are major components of concrete, and they too leach into the ground and water as it weathers. Inside homes and offices, drywall contains salts that reach the environment following demolition and disposal. Rapid development globally is a major driver of the salinity crisis, Kaushal says.
DE-ICERS
The U.S. uses 20 million metric tons of road salt each year, not counting the smaller amounts spread on residential walks and driveways. “Safety is obviously crucial, but don’t use more than is necessary,” Kaushal advises.
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