MICHEL MARTIN, HOST:
We've been reporting on how the conflict in the Middle East has disrupted global supply chains for things like oil, food and fertilizer. Now it's affecting the supply of fluoride for U.S. drinking water. NPR's Pien Huang explains why some U.S. water systems are cutting back on fluoride.
PIEN HUANG, BYLINE: This week, the city of Baltimore's public water system sent a notice to its 1.8 million customers. The fluoride in their drinking water was getting cut nearly in half, from 0.7 to 0.4 milligrams per liter. Matthew Garbark, director of the Baltimore City Department of Public Works, says the problem has been building.
MATTHEW GARBARK: We were alerted a couple weeks ago that our supplier was going to be reducing the supply from three deliveries per month to two.
HUANG: Those are deliveries of hydrofluorosilicic acid, a chemical that's often used to add fluoride to drinking water to prevent cavities and tooth decay.
GARBARK: We don't manufacture it. We don't produce it. All of our chemicals are purchased, and they rely on the supply chain in order to get to our plants.
HUANG: It comes to the water treatment plant as a liquid transported in big, 5,000-gallon tanker trucks. Much of it is made in Israel. Dan Hartnett is chief policy officer at the Association of Metropolitan Water Agencies.
DAN HARTNETT: As we understand it, one of the main suppliers in Israel has lost a number of their employees temporarily because they've been called up into service in the Israeli military. So that's essentially shut down production at their facility in Israel, so they haven't been producing the acid. They haven't been able to ship it out.
HUANG: Hartnett says it isn't causing widespread problems yet.
HARTNETT: I think there's concern that if this conflict in Iran goes on for longer and the supply chain continues to be disrupted, then a growing number of systems may start to face those similar types of challenges.
HUANG: Ben Thompson is director of production at WSSC Water, which serves 1.9 million residents in the Maryland suburbs outside Washington, D.C. His supplier said it would ship 20% less of the chemical going forward, so they're reducing their fluoride levels.
BEN THOMPSON: So for me, it was looking at the control order from our vendor, trying to stretch out our supplies, because it's unknown to what extent or how long this will continue.
HUANG: Thompson says water use shoots up in the summer months, so he wants to make sure there's some consistent fluoride in the water.
THOMPSON: The water is safe for use. This reduction does not in any way impact water quality. It is simply a reduction in the fluoride treatment.
HUANG: Thompson says these reductions are temporary. WSSC aims to bring fluoride levels back fully in line with public health recommendations when the supply returns, but he couldn't predict when that would be.
Pien Huang, NPR News. Transcript provided by NPR, Copyright NPR.
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