The cancer-causing chemical found in dust blowing from the TXI Riverside Cement plant in Rubidoux isn’t just a concern for people living in northwest Riverside County.

Prevailing winds carried hexavalent chromium-laden dust into south Colton and south Rialto, testing by the South Coast Air Quality Management District found earlier this year.

Higher than average levels of the toxic chemical were found in dust near La Cadena Drive and Rancho Avenue, Pepper Avenue and Interstate 10, and Riverside Avenue and I-10.

Hexavalent chromium is the chemical made famous by Erin Brockovich after it contaminated water in Hinkley. Residents there won more than $300 million from Pacific Gas & Electric for heart, respiratory and reproductive problems they blamed on the chemical.

Now, alarmingly, it has been found along the Riverside-San Bernardino border during cancer-risk studies throughout the LA Basin from 2004 to 2006.

It took additional months of studies, sampling and chemical fingerprinting to pinpoint Riverside Cement as the source.

Already, a class-action lawsuit has been filed, alleging the plant is responsible for illnesses including cancer, respiratory problems and skin irritation.

Residents of Bloomington and south Colton have been concerned for years about the dust that coats their cars, their landscaping and the inside of their homes.

Many thought it came from California Portland Cement in Colton. But AQMD officials don’t believe Cal Portland is responsible for the spread of hexavalent chromium.

Executive Officer Barry Wallerstein told me the Colton plant does a much better job of controlling airborne dust than Riverside Cement has done.

AQMD inspectors found Cal Portland Cement has better equipment and better practices for controlling dust:

The plant covers its piles of clinker, made from raw material fired at high temperatures into bricks that are ground up later to make cement. In addition, some of its conveyors are enclosed, AQMD officials said.

Officials believe hexavalent chromium became airborne in dust that was blown off the Riverside Cement site when workers moved clinker. Its clinker piles were left completely open, the AQMD told me.

Riverside Cement spokesman Frank Sheets told me Monday his company has begun spraying the clinker with water and a dust suppressant when it’s being moved, since AQMD cited it recently for dust problems.

It also reduced the number of clinker deliveries and stepped up maintenance of vacuums that remove clinker dust along its conveyor belts, Sheets said.

The company is evaluating the way clinker is delivered to the plant, and may eliminate outdoor storage, he said.

The AQMD and Supervisor Josie Gonzales, whose district includes the affected neighborhoods, will hold a community meeting to discuss the results of testing at the Cal Portland site at 6:30 p.m. May 29 at Colton High School.

Residents should also be able to get their questions answered about the hexavalent chromium in the dust from the Riverside Cement plant at that meeting.

Gonzales said through a spokesman that she wants residents to get “complete and accurate information.”

That’s important, because it will help them take necessary precautions for their health.