Perchlorate Contamination in the Arden Cordova Water Service Area
RANCHO CORDOVA, SACRAMENTO COUNTY, CALIFORNIA
Based upon the information reviewed, there was and is a completed exposure pathway to perchlorate-contaminated water in the Cordova System. Adult residents who lived near and employees who worked at businesses near the contaminated wells may have been or may be exposed on a regular basis to the perchlorate when they drank water and washed or showered with the water. Other exposures occurred over a short duration resulting in a very low dose to the customers and visitors who occasionally frequented the business establishments located near the perchlorate-contaminated wells.
It is hard to say when the perchlorate first contaminated the Cordova System wells but it may have been as early as 1987. As a result of being notified of the perchlorate contamination on February 11, 1997, Southern California Water Company stopped the distribution of water with levels of perchlorate greater than 18 ppb (USEPA's provisional reference dose based on a 70 kg individual consuming two liters of water a day). The water from several Cordova System wells that are currently in use contain perchlorate in lower concentrations (<18 ppb).
Since the uncertainty factors are supposed to account for the somewhat limited toxicological information, it is conceivable that as more toxicological data becomes available, a change in the (provisional) reference dose may occur.
The estimated dose for a adult resident exposed to water from well #13 or a worker exposed to well #15 or 16 exceed the provisional reference dose range which means that noncancer (thyroid depression) health effects may have occurred when the adult resident was exposed to water from these wells. However, because there is a very large uncertainty factor associated with the provisional reference dose and the estimated doses do not approach the NOAEL, it is unlikely that these exposures did cause any noncancer health effects. These wells are no longer being used, thus any noncancer health effects that may have occurred should no longer be occurring now that the exposure has ceased.
The estimated dose for a frequent adult customer/visitor exposed to water from well #15 or 16 does not exceed the provisional reference dose range. This means that noncancer (thyroid depression) health effects would not have occurred to the frequent adult customer/visitor drinking or washing with water from well #15 or 16.
The estimated dose for adult resident exposed to water from well #11 or 14 does not exceed the provisional reference dose range. This means that noncancer (thyroid depression) health effects would not have occurred or should not be occurring to the adult resident drinking or washing with water from well #11 or 14. The estimated dose for worker or a frequent adult customer/visitor exposed to water from well #19 does not exceed the provisional reference dose range. This means that noncancer (thyroid depression) health effects would not have occurred or should not be occurring to the worker or a frequent adult customer/visitor drinking or washing with water from well #19. Wells #11, 14, and 19 are currently in use.
Based upon the information available at the time this health consultation was written, CDHS concludes that well water from Cordova System wells #13, 15, and 16 may have posed a health hazard when these wells were in use. Since the water from these three wells are no longer being used, these wells do not pose a current health hazard. Additionally, the perchlorate levels in the other Cordova System wells that are currently in use do not pose a health hazard.
The Public Health Recommendations and Actions Plan (PHRAP) for this site contains a description of actions taken, to be taken, or under consideration by ATSDR and CDHS or others at and near the site. The purpose of the PHRAP is to ensure that this health consultation not only identifies public health hazards, but also provides a plan of action designed to mitigate and prevent adverse human health effects resulting from exposure to hazardous substances in the environment. The CDHS and ATSDR will follow-up on this plan to ensure that actions are carried out.
- Southern California Water Company immediately discontinued the delivery of perchlorate contaminated water and now is only delivering water with less than 18 ppb perchlorate.
- Southern California Water Company has communicated with the Cordova System water customers by holding a workshop and has released several public notices to keep their customers informed about the perchlorate problem.
- CDHS prepared a fact sheet about perchlorate and health. CDHS made this fact sheet available to the affected water purveyors including the Southern California Water Company.
- CDHS has asked ATSDR to conduct a dose reconstruction exposure investigation of perchlorate exposure in the Cordova System. ATSDR has agreed to come to visit California and investigate the effort that would be needed to conduct the dose reconstruction.
- CDHS is in the process of submitting a protocol to ATSDR to conduct a health statistics review of the CDHS Genetic Disease Branch data of newborn thyroid testing in relation to doses from the dose reconstruction exposure investigation.
- The Air Force and the Perchlorate Study Group (a number of manufacturers and users of perchlorate) are sponsoring an investigation into fate and transport questions regarding perchlorate. For instance, they will investigate if is perchlorate is taken up and bioconcentrated by vegetable crops and the skin permeability of perchlorate.
- The Air Force and the Perchlorate Study Group are also sponsoring a series of animal studies to address some of the information lacking in understanding perchlorate toxicology. CDHS cooperative agreement staff along with other state and federal scientists, were asked by the Air Force to recommend and oversee the planning of the animal studies. As of August 1997, the study protocols have been finalized and the process of choosing a laboratory to conduct the studies is underway. A report on the studies is expected in mid-summer 1998.
- Continue communicating with the Cordova System water customers about the perchlorate issue. For instance, send perchlorate fact sheet or some other type of summary in the next mass mailing to the Cordova System well users.
- Discontinue, as Southern California Water Company has been doing, using wells that have levels of 18 ppb or greater of perchlorate.
- If indicated based on new toxicological information, review toxicological evaluation of past and current perchlorate exposures in the Sunrise District.
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ENVIRONMENTAL AND HEALTH EFFECTS ASSESSORS:
Marilyn C. Underwood, Ph.D.
Environmental Health Investigation Branch
California Department of Health Services
COMMUNITY RELATIONS COORDINATOR:
Jane Riggan, M.S.W.
Public Health Social Work Consultant II
Environmental Health Investigations Branch
California Department of Health Services
ATSDR REGIONAL REPRESENTATIVE
Senior Regional Representative
Office of Regional Operations, ATSDR - Region IX
ATSDR TECHNICAL PROJECT OFFICER:
William Greim, M.S., M.P.H.
Division of Health Assessment and Consultation
Superfund Site Assessment Branch, State Programs Section
The Perchlorate Contamination in the Citizens Utilities' Suburban and Security Park Water Service Areas, Aerojet-General Corporation Health Consultation was prepared by the California Department of Health Services under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the health consultation was initiated.
Technical Project Officer, SPS, SSAB, DHAC
The Division of Health Assessment and Consultation, ATSDR, has reviewed this health consultation and concurs with its findings.
Chief, SPS, SSAB, DHAC, ATSDR