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The Arizona Department of Health Services concludes that the symptoms reported by the Laveen and Gila River residents during the nitric acid release are consistent with the effects of nitrogen oxide and nitric acid exposure. However, due to the limited air monitoring data, it is difficult to verify the exact concentrations of the by products produced from the oxidation of the acids. At the time of the release, the site posed an urgent public health hazard, and evidence exists that exposures did occur. Currently, though, the site poses no public health hazard, as there is no longer any release of nitric acid or its constituents into the air and no human exposure is occurring.

The low concentrations of HCL and HNO3 that were measured by ADEQ do not account for all of the health symptoms experienced by residents. However, samples could not be taken inside the plume due the danger posed to emergency response personnel. It is also likely that exposure to nitrogen oxides formed after the release may be responsible for some of the health effects observed.

The acute and severe NOx exposure symptoms noted are similar to those reported by residents during the health effects investigation. While the lack of air monitoring data makes it impossible to verify, ADHS concludes that the symptoms seen in residents are consistent with NOx and HNO3 exposure.



  1. Future ADEQ HAZMAT air sampling needs to measure for all potential toxic by products generated. ADHS must better assist ADEQ to determine what toxic substances to sample for during an emergency release in order to have adequate data to evaluate the public health risk.
  2. In the future, Poison Control centers will be contacted as part of the emergency response team in order to disseminate information to all area hospitals and clinics following toxic releases. This will ensure proper treatment and diagnosis by emergency rooms and primary care doctors unfamiliar with treating rare environmental exposures.


  1. ADHS issued a follow up press release recommending that area primary care doctors to consult with the poison control center to ensure that any remaining residents with symptoms receive proper diagnosis and care.


  1. US Census Data,, 1990.

  2. TOMES Database, acid, August 1998.

  3. TOMES Database, acid, August 1998.

  4. TOMES Database, dioxide, August 1998.

  5. TOMES Database, dioxide, August 1998.

  6. Lipsett, Michael, Hazardous Materials Toxicology: Clinical Principles of Environmental Health , Ch. 97 -Specific Toxins :Oxides of Nitrogen and Sulfur, p.964- 972, 1992.

  7. Pippia, Dino, Laidlaw Report to ADEQ, July 6, 1998.

  8. ADEQ HAZMAT Report: Hudson Farm Nitric Acid Incident, July 1, 1998.

  9. Faisst, Eric, Gila River Indian Community :Nitric Acid Spill Survey Report, July 24, 1998.


Pragathi S. L. Tummala, MPH
Environmental Programs & Projects Specialist
Office of Environmental Health
Bureau of Epidemiology & Disease Control

Will Humble, MPH
Office of Environmental Health
Bureau of Epidemiology & Disease Control

ATSDR Regional Representative

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

ATSDR Technical Project Officer

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


The Hudson Farm Nitric Acid release Health Consultation was prepared by the Arizona 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.

William Greim
Technical Project Officer, SPS, SSAB, DHAC

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

Richard Gillig

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