U.S. Not Informed of Plant’s Toxic Leak : Pollution: About 10,000 people were evacuated in Mexicali. EPA says such information is supposed to be supplied under an agreement with Mexico.

Federal environmental officials said Thursday that Mexican environmental officials failed to notify them of a release of hydrochloric acid fumes at a Mexicali chemical plant Sunday that required hospital treatment for 43 people and forced evacuation of about 10,000 people.

Despite a 3-year-old accord under which U.S and Mexican authorities agreed to notify each other promptly of border environmental incidents, a federal Environmental Protection Agency spokesman said the EPA did not learn of the incident at the Quimica Organica de Mexico plant until two days after it occurred.

Notification came from an unidentified non-governmental source instead of the EPA’s counterpart agency in Mexico, SEDUE (a Spanish acronym for Secretariat for Urban Development and Ecology), the spokesman said.

“There has been no official communication,” said EPA spokesman David Schmidt, who is based in San Francisco. “We are concerned that the Mexican government did not make that notification. . . . We would characterize it as a serious incident because it did involve an evacuation and did involve some people being injured off the site.”

The incident, and the EPA’s publicly expressed concern about lack of notification, take on particular significance because border environmental hazards are a key issue in discussions of the proposed free trade pact between the two countries.

EPA administrators plan to discuss the case with SEDUE representatives, who reportedly have ordered the shutdown of the plant. SEDUE administrators in Mexicali and Tijuana could not be reached for comment.

The release occurred because of a leak in a tank of hydrochloric acid at about 8 p.m., according to various accounts. The plant, where pesticides and other agricultural chemicals are manufactured, is about about six miles from the international border.

A toxic cloud wafted over adjacent working-class neighborhoods, causing the evacuation of 10,000 residents, according to Mexican environmental activists and a Mexicali city spokesman.

The situation was declared under control within an hour, city officials said. Most of the 43 injuries were minor, mainly children and young people complaining of nausea and headaches, said Mexicali spokesman Arturo Galvan.

But there was conflicting information Thursday on the injuries. A Mexicali environmental activist said three people remain hospitalized--an account Galvan disputed. The EPA was informed of 30 injuries, Schmidt said.

The Mexicali activist, Fernando Medina of the Civic Ecological Disclosure Committee, said emergency authorities responded quickly and effectively.

“It was handled well,” he said. “Some of these neighborhoods have rapid access to main streets but others do not, so there was a lot of panic among the people. . . . And now people are very angry.”

After protests at Quimica Organica, SEDUE has ordered chemical operations at the plant shut, Galvan said.