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The Arizona Department of Health Services (ADHS), Office of Environmental Health (OEH) responds to environmental emergencies at the request of the Arizona Department of Environmental Quality (ADEQ) to provide public health related advice. ADHS was asked to provide health related information regarding exposure to a mixture of pesticides.

On August 25, 1996, a security guard for the San Carlos Apache Tribe noticed an unusual odor emanating from the area of the tribal Head Start/Legal Aid building at 31 Tonto St., in San Carlos, AZ. On August 26, office workers in the building noticed an odor, but did not investigate the origins. On August 27, the office workers noticed that the odor had become much stronger. They left the building and returned later in the morning, at which time they began to experience eye and nose irritation, headaches, and nausea. Tribal officials were contacted and the building was evacuated along with other surrounding buildings including the day care center and school classrooms behind the Head Start building. The local Indian Health Service sanitarian, Kenny Hicks, was asked to make an evaluation as to the cause of the odor, which appeared to be coming from the basement of the building. The ADEQ Emergency Response Team (ERT) was contacted and asked for assistance with the situation. An area around the building of approximately 1/4 mile radius was evacuated as a precaution, until the cause of the problem could be determined.

The Head Start workers proceeded to the emergency room of the local Indian Health Service Hospital to be evaluated. The ADEQ on site response person, Mike Malone, determined that an emergency clean-up of the building was necessary and after consulting with the Tribal authorities, called in a request for a clean-up crew to be dispatched from Tucson. The remediation crew arrived at approximately 10 p.m. and began the site evaluation process. The basement area of the building was the apparent source of the vapors. Inspection of the basement using level A protective equipment, which consists of complete personnel enclosure and self contained breathing apparatus, revealed the area was flooded with water with several unidentified barrels floating in the water. Labels were located on at least one barrel and the product appeared to be a herbicide, 2,4-BIS(isopropyl amino)-6-methoxy-s-triazine, used to control annual and perennial grasses and weeds. No manufacturer’s product name could be found on the barrel.

The initial clean up effort consisted of pumping out the flooded basement and storing the liquid in an open top portable storage tank. After the bulk of the liquid was removed, the clean up crew entered the basement in level A protective gear. The remaining materials were packed in approved transportation containers after samples were taken to categorize the materials. Field classification of the materials indicated the main component was pentachlorophenol. Subsequent to the removal of all materials, the basement was steam cleaned. The materials collected during the operation were sent to a registered hazardous materials treatment facility in California for proper disposal.


The ADHS, OEH was contacted by the ADEQ, ERT on August 28 requesting assistance concerning the public health threat of exposure to the identified product.

The OEH representative arrived at the incident command center on August 29 at 8 a.m. and met with the tribal representatives and the ADEQ representative to assess the remediation effort and to discuss the evacuation plans. A meeting with the Tribal Emergency Response Committee (TERC) to assess the overall program took place at 9 a.m. in the Tribal Council room. The U.S. EPA representative briefed the assembled persons on the remediation effort, with the clean-up scheduled to be finished by late afternoon or early evening. Another meeting was scheduled for 3 p.m. to determine if a change in plans was needed. It was decided that since the products in the basement did not appear to be a threat to the surrounding areas that these buildings would be inspected with a photo ionization detector style organic vapor meter to detect any residual vapors. If no vapors were detected, the building would be allowed to reopen for business, with the exception of the day care center, the elementary school, and the residence next door to the Head Start building. The buildings were inspected and cleared for re-occupancy.

The OEH representative met with the Head Start personnel to determine if any were still experiencing any residual effects of the exposure to the herbicide. There were five persons in the office at the time of the evacuation. None indicated any residual effects. The members of the Legal Aid office were located during the 3 p.m. meeting and questioned regarding any lingering health effects. The hospital emergency room admitting log was examined by the Indian Health Service District Sanitarian and the OEH representative on August 28 in an attempt to locate any others who may have been impacted by the vapors. Only one person was located with any symptoms attributed to the release. Efforts to locate this person were not successful during the time at the site. Follow-up inquiries took place on September 3 and 16.


As stated previously, no manufacturer’s product name could be found on the barrel, however, the herbicide, 2,4-BIS(isopropyl amino)-6-methoxy-s-triazine, was located on a label. A product containing this chemical (Prometon 5PS) was found through the electronic database, Micomedex, Inc. TOMES PLUS and a Material Safety Data Sheet (MSDS) was obtained from the manufacturer. The MSDS listed the herbicide as toxic when inhaled, based on animal studies. There are no occupational exposure standards established for the herbicide.

A sample of the herbicide was analyzed using a field Hazardous Categorization Kit which detected Pentachlorophenol as the primary ingredient of the pesticide. Pentachlorophenol was not listed on the MSDS as an ingredient of the herbicide but may have been used as carrier compound. One of the other ingredients of the material is sodium chlorate. Sodium chlorate is known to cause upper respiratory irritation as well as eye irritation but probably not in this situation because it is not volatile and would not be inhaled as a vapor. Exact exposure information for this incident is not available. Based upon the interviews with the persons from the site, this short term exposure to the vapors did not appear to exceed a few hours in duration. Based upon this information, further evaluations should not be necessary.


Based upon the available toxicological data on the ingredients of the materials, there should be no long term effects from exposure to the materials. This determination is made based upon the length of time the occupants of the building were exposed, the low concentration of the air borne vapors and the toxicological information available. Due to the available evidence that the vapors from the spill have not resulted in any detrimental health effects among those exposed, this consultation will be completed with this report.


Due to the nature in which the materials were stored in the basement of an occupied office building, it was recommended to the Tribal officials that an inventory of buildings be conducted, and that all materials be relocated to proper storage facilities to prevent this type of incident from occurring again.


Material Safety Data Sheet for Prometon 5PS, Ciba-Geigy Corporation

Micromedex, Inc. TOMES PLUS, electronic database, July 1996 edition.


Arizona Department of Health Services, Office of Environmental Health

Brian W. Hasty, Environmental Toxicologist

Lee A. Bland, Chief, Office of Environmental Health, Principal Investigator

ATSDR Regional Representative

William Nelson
Office of Regional Operations, Region IX
Office of the Assistant Administrator

ATSDR Technical Project Officer

William Greim
Division of Health Assessment and Consultation
Superfund Site Assessment Branch


The San Carlos Apache Chemical Spill Health Consultation was prepared by the Arizona Department of Health Services, Office of Environmental Health 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.

William Greim
Technical Officer, SPS, SSAB, DHAC

The Division of Health Assessment and Consultation, ATSDR, has reviewed this Health Consultation and concurs with its findings.

Richard Gillig

Table of Contents The U.S. Government's Official Web PortalDepartment of Health and Human Services
Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy NE, Atlanta, GA 30341
Contact CDC: 800-232-4636 / TTY: 888-232-6348

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