by Natalie Solis and Vicki Chen, originally posted on  January 24, 2017

Editor’s Note: This story has been updated to more accurately reflect which schools have been cleared after a second round of testing. The original report aired on FOX 4 on January 24, 2017.

Dallas ISD has confirmed to FOX 4 that the drinking water at four schools has been cleared as safe for consumption after initially showing elevated levels of lead and copper.

The update comes after the district revealed in January that it had discovered contaminated drinking water at seven schools.

DISD contracted with two private companies to randomly sample the drinking water at all 227 schools during the fall semester. Each school had at least one drinking water source sampled.

While there is no law requiring school districts to test their water, DISD is among dozens of districts in Texas that decided to test their water after the lead contamination crisis in Flint, Michigan made national headlines earlier this year. Lead exposure can lead to negative health effects, particularly in children, according to the Environmental Protection Agency (EPA).

The Environmental Protection Agency recommends no more than 20 parts per billion (ppb) of lead in water for schools. Most school districts are following the more restrictive measure of 15 ppb applied to public water systems, including DISD. The EPA recommends action if copper levels exceed 1.3 parts per million.

Results released in January revealed levels of lead at James Madison, Skyline and Woodrow Wilson High Schools above EPA action levels.

Elevated levels of copper were detected at Billy Dade Middle School, Preston Hollow Elementary School, Wilmer-Hutchins High School and Wilmer-Hutchins Elementary School.