What appeared to be a major increase in use of a particularly harmful weed killer in San Mateo County turned out to be an error in reporting by the state.
The state’s most recent data on pesticide use in the county indicated an alarming increase in the spraying of Oryzalin, from 1,900 pounds in 2005 to 105,000 pounds the following year.
The Department of Pesticide Regulation launched an investigation into its figures after The Examiner questioned the increase. State officials acknowledged Friday there had been a mistake in the reporting.
Revised numbers show that only 1,507 pounds of Oryzalin was used in the county in 2006, a drop from the previous year. The total for all “most toxic” pesticides used in 2006 is now 153,500 pounds rather than 257,000, also a decrease from the previous year.
“Many errors result when a decimal point is misplaced, or when the use is reported in gallons of product used when it actually was ounces,” said Veda Federighi, DPR assistant director for external affairs. “The latter occurred in this instance.”
Federighi said that DPR has error-checking software to catch data entry errors, but that “some inevitably slip through in the millions of data fields that are generated each year by pesticide use reports.”
The original reporting confused county officials, although deputy agricultural commissioner Maria Mastrangelo had suspected there was a problem with the data.
County officials said the use of less-toxic pesticides has become a new trend.
The Oryzalin issue came to light when researchers from Sustainable San Mateo County, a community group, gathered the state’s pesticide numbers for its annual report. The state requires all companies to submit its pesticide use to the counties, which in turn reports those numbers on a monthly basis to the state.
“We questioned the county about the [Oryzalin] usage, but they hadn’t figured it out prior to our printing,” said Joe Rois, project coordinator for Sustainable San Mateo. “We couldn’t find out where the spraying was done. It was frustrating for us.”
Oryzalin is commonly used to stunt weeds from curling around roadways, railroads and power lines. The carcinogenic substance has been linked to breast cancer, birth defects and ground contamination.