More than 10 million Texans have consumed drinking water with some level of atrazine — a toxic herbicide — with 472 water utility systems statewide testing positive in at least one detection, according to a new report from an environmental group.

Comparing the test results submitted by water utilities to state environmental regulators to those from U.S. Environmental Protection Agency, the Washington, D.C.-based Environmental Working Group concluded that water utilities are testing for atrazine at times when farmers aren't using it — the growing season typically spans late spring and early summer — and also appear to be lowballing their numbers. The group is calling for updates to federal drinking water standards.

The report found that nearly 30 million Americans have atrazine in their tap water — and that Texans who live near sorghum or corn-growing areas are more likely to have contaminated drinking water.

The 472 Texas utilities with atrazine contamination serve nearly 10 million people. Water utilities in Texas send their data to the Texas Commission on Environmental Quality, the state’s environmental regulatory agency.

In their analysis, EWG compared 2017 federal testing data collected at utilities in seven states, including Texas, with atrazine levels reported to state authorities over the same period. For 70 percent of utilities analyzed, the EWG found that tests were conducted outside periods of the atrazine spikes or that reported levels were below what EPA tests found.

Olga Naidenko, an EWG senior science advisor, said many water utilities stay in compliance with drinking water regulations by avoiding testing during seasonal spikes of atrazine.

“The utility, by playing the dates game, may not pick up the spike,” said Naidenko, one of the report’s authors. “By testing before or after the spike, they are effectively missing the spike or reporting very low levels.”

Russell Hamilton, executive director of the Texas Water Utilities Association, said he is concerned when he hears reports like EWG's, but said there are checks and balances in place to address elevation of herbicides like atrazine in water supplies.

"If atrazine is detected, that's when the state takes action and there are steps in place where you have to start additional or advanced treatment procedures," said Hamilton, whose organization provides training to those seeking to become licensed as water supply operators.

Brian McGovern, a spokesman for the state environmental agency, said the TCEQ uses third-party contractors to collect all chemical compliance samples, including those for atrazine. He said that monitoring would increase to a quarterly basis if atrazine levels rose above the EPA's maximum contaminant levels or above the regulatory detection limit.

In Texas, levels have not gone above the limit, but the EWG report said water utilities in Illinois, Kansas, Kentucky and Ohio had atrazine spikes much higher than the federal legal limit but the EWG recommends that the atrazine limit for drinking water be at 0.1 ppb. Only two Texas communities — Huntsville and Port Lavaca — were a part of the EPA monitoring program in 2017, according to Sarah Graddy, deputy director of communications at EWG.

Texas must adopt regulations at least as stringent as those adopted by the EPA under the Safe Water Drinking Act, according to the TCEQ website. The current EPA standard for atrazine in drinking water is 3 parts per billion (ppb), but EWG says it should be 0.1 ppb.

Naidenko said EWG cannot determine whether there is an intent by water utilities to deceive but said what is truly important is whether or not people consuming the contaminated drinking water are made aware of the issue. Atrazine can disrupt hormones and hurt fetuses, leading to greater risks of cardiovascular disease or developmental delays, the group said.

A medical study from the University of Texas Health Science Center at Houston suggests a connection between maternal atrazine exposure and gastroschisis, a birth defect in the wall of a baby’s abdomen. Another study by UTHealth “observed modest, but consistent, associations” between maternal atrazine exposure and various deformities in male genitalia.

Under the Safe Drinking Water Act, last updated in 1996, only annual averages of atrazine need to be reported. Naidenko said it is important for state water authorities to advocate for “greater scrutiny” and to require that testing take place at a time when a spike in atrazine is expected.

“We know there is under-detection because of when utilities take their samples,” Naidenko said. “All we can say is it looks suspicious that the compliance test does not show the same kind of spike as when testing is conducting by testers who are not associated with the water utilities.”

The Office of Pesticide Programs at the EPA is studying whether or not it is appropriate to revise drinking water standards as they relate to atrazine, according to an EPA spokesperson. The EPA said it continues to evaluate peer-reviewed data and information on the health effects of atrazine and simazine, another dangerous herbicide.

TCEQ said Texans can find information about their drinking water supply at Texas Drinking Water Watch, which allows users to search by county and system type, among other parameters. EWG said atrazine can be removed from water using common faucet-mounted filters or pitchers with a filter.