The decision came three months after an expert panel—convened by the University of California on behalf of the OEHHA to review the chromium 6 science—released its report stating there is no evidence that chromium 6 causes cancer in humans when consumed in water.

The panel proposed that, until the a more definitive study is complete, California should continue to consider its current drinking water standard (maximum contaminant level) of 50 ppb for "total chromium" to be protective of public health. The federal standard is 100 ppb. The U.C. panel’s report is available online at www.oehha.ca.gov/public_info/facts/pdf/crpanelrptfinal901.pdf

OEHHA and the California Department of Health Services (CDHS) committed in March 2001 to develop the nation’s first PHG and drinking water standard specifically for chromium 6, also known as hexavalent chromium. The chromium 6 PHG, which OEHHA will develop by Spring 2003, will replace the withdrawn PHG for "total" chromium consisting of both chromium 6 and chromium 3, an essential nutrient.

DHS will use the new PHG to develop a chromium 6 drinking water standard. Legislation signed by Governor Gray Davis in October 2001 (Senate Bill 351 by Senator Deborah Ortiz) requires DHS to adopt a chromium 6 drinking water standard by January 2004.

A major study planned by the National Toxicology Project at the request of OEHHA and CDHS, will hopefully provide definitive data of the cancer risks of chromium 6 in drinking water. The federal study is expected to take up to five years to complete.

northern california cancer study
In August 2001, at the request of the Santa Cruz County Public Health Department, the Greater Bay Area Cancer Registry at the Northern California Cancer Center completed a review of the incidence of lung and overall cancer occurring in areas served by District wells having detected levels of chromium 6.

This analysis revealed no apparent excess of either lung cancer or overall cancer incidence among residents receiving water from wells in Rio Del Mar, Aptos, and La Selva Beach compared to the rest of the region.

aromas red sands source water assessment
In April 2002, a source water assessment that investigated potential contamination sources and the susceptibility of the District’s drinking water wells to identified contamination threats was completed by Todd Engineers. The study identifies onsite residential septic systems and potential leakage from sewer lines as the greatest threat to the District’s drinking water wells in the Aromas Red Sands Aquifer.

An additional component of the study analyzes the probable cause of the occurrence of chromium 6 in the Aromas Red Sands Aquifer and the potential for increased concentrations of chromium 6 due to in-home reverse osmosis systems in areas using septic systems for wastewater disposal.

The study could find no man-made sources of chromium 6 and found that environmental conditions tend to favor chromium 6 production from dissolved trivalent chromium found in the local geology. These findings led to the conclusion that the occurrence of chromium 6 in the aquifer is natural.

Reverse osmosis systems can result in a significant increase in water usage depending on the type of system used. Reverse osmosis discharges to the regional wastewater treatment plant will have little impact on groundwater quality, while discharges to onsite septic systems can infiltrate groundwater. Point of use systems (treatment at the tap) will have little impact on water use or chromium 6 concentrations in groundwater due to the small amount of the water supply that is treated. Point of entry (all water flowing into the house is treated) reverse osmosis systems can more than double the amount of water used by the household, potentially overloading septic systems and the discharged wastewater may have chromium 6 concentrations two to three times that of the inflow water supply.

Copies of the Source Water Assessment Executive Summary are available free-of-charge at the District headquarters office.

potential proposition 50 grant funding
A grant proposal for a pilot treatment project for chromium 6 in District wells is included in the list of priority projects for Santa Cruz County being considered for Proposition 50 (Water Bond) funding. At this time, there are no guarantees that a grant would be awarded.