User:Wikiworkenviro/sandbox

Occupational Uses
Hydrazine is a colorless, fuming, oily liquid with an ammonia-like odor that is toxic and highly flammable. It is used in the synthesis of chemical and blowing agents, manufacturing of paints and dyes, nuclear reactor waste and boiler water treatment, adhesive polymerizations, spandex fibers, rocket and aerospace vehicle propellants, military aircraft emergency fuel, submarine generators, agricultural pesticides, pharmaceuticals and cancer research. Outside of these occupational settings, exposure to hydrazine is also possible in small amounts from tobacco smoke.

The United States Air Force (USAF) regularly uses H-70, a 70% hydrazine 30% water mixture, in operations employing the General Dynamics F-16 “Fighting Falcon” fighter aircraft and the Lockheed U-2 “Dragon Lady” reconnaissance aircraft. The single jet engine F-16 utilizes hydrazine to power its Emergency Power Unit (EPU), which provides emergency electrical and hydraulic power in the event of an engine flame out. The EPU activates automatically, or manually by pilot control, in the event of loss of hydraulic pressure or electrical power in order to provide emergency flight controls. The single jet engine U-2 utilizes hydrazine to power its Emergency Starting System (ESS), which provides a highly reliable method to restart the engine in flight in the event of a stall.

Health Hazards
Potential routes of hydrazine exposure include dermal, ocular, inhalation and ingestion. Hydrazine exposure can cause skin irritation/contact dermatitis and burning, irritation to the eyes/nose/throat, nausea/vomiting, shortness of breath, pulmonary edema, headache, dizziness, central nervous system depression, lethargy, temporary blindness, seizures and coma. Exposure can also cause organ damage to the liver, kidneys and central nervous system. Hydrazine is documented as a strong skin sensitizer with potential for cross-sensitization to hydrazine derivatives following initial exposure.

The official guidance on hydrazine as a carcinogen is mixed but generally there is recognition of potential cancer-causing effects. The National Institute for Occupational Safety and Health (NIOSH) lists it as a “potential occupational carcinogen”. The National Toxicology Program (NTP) finds it is “reasonably anticipated to be a human carcinogen”. The American Conference of Governmental Industrial Hygienists (ACGIH) grades hydrazine as “A3 - confirmed animal carcinogen with unknown relevance to humans”. The U.S. Environmental Protection Agency (EPA) grades it as “B2 - a probable human carcinogen based on animal study evidence”.

The International Agency for Research on Cancer (IARC) rates hydrazine as “2A – probably carcinogenic to humans” with a positive association observed between hydrazine exposure and lung cancer. Based on cohort and cross-sectional studies of occupational hydrazine exposure, a committee from the National Academies of Sciences, Engineering and Medicine concluded that there is suggestive evidence of an association between hydrazine exposure and lung cancer, with insufficient evidence of association with cancer at other sites. The European Commission’s Scientific Committee on Occupational Exposure Limits (SCOEL) places hydrazine in carcinogen “group B - a genotoxic carcinogen”. The genotoxic mechanism the committee cited references hydrazine’s reaction with endogenous formaldehyde and formation of a DNA-methylating agent.

Exposure Treatment
In the event of a hydrazine exposure-related emergency, it is recommended to remove contaminated clothing immediately, wash skin with soap and water, and for eye exposure remove contact lenses and flush eyes with water for at least 15 minutes. Exposed individuals should seek medical attention as soon as possible. There are no specific post-exposure laboratory or imaging recommendations, and medical work-up may depend on the type and severity of symptoms. Exposed patients should be treated symptomatically with special attention given to potential lung and liver damage. Past cases of hydrazine exposure have documented success with Pyridoxine (Vitamin B6) treatment, which could be considered.

Occupational Exposure Limits
NIOSH Recommended Exposure Limit (REL): 0.03 ppm (0.04 mg/m3) 2-hour ceiling

OSHA Permissible Exposure Limit (PEL): 1 ppm (1.3 mg/m3) 8-hour Time Weighted Average

ACGIH Threshold Limit Value (TLV): 0.01 ppm (0.013 mg/m3) 8-hour Time Weighted Average

* The odor threshold for hydrazine is 3.7 ppm, thus if a worker is able to smell an ammonia-like odor then they are likely over the exposure limit. However, this odor threshold varies greatly and should not be used to determine potentially hazardous exposures.

For aerospace personnel, the USAF uses an emergency exposure guideline, developed by the National Academy of Science Committee on Toxicology, which is utilized for non-routine exposures of the general public and is called the Short-Term Public Emergency Exposure Guideline (SPEGL). The SPEGL, which does not apply to occupational exposures, is defined as the acceptable peak concentration for unpredicted, single, short-term emergency exposures of the general public and represents rare exposures in a worker’s lifetime. For hydrazine the 1-hour SPEGL is 2 ppm, with a 24-hour SPEGL of 0.08 ppm.

Proper Handling and Medical Surveillance Program
A complete surveillance program or hydrazine should include systematic analysis of biologic monitoring, medical screening and morbidity/mortality information. The CDC recommends surveillance summaries and education should be provided for supervisors and workers. Pre-placement and periodic medical screening should be conducted with specific focus on potential effects of hydrazine upon functioning of the eyes, skin, liver, kidneys, hematopoietic, nervous and respiratory systems.

Common controls used for hydrazine include process enclosure, local exhaust ventilation and personal protective equipment (PPE). Guidelines for hydrazine PPE include non-permeable gloves and clothing, indirect-vent splash resistant goggles, face shield and in some cases a respirator. The use of respirators for the handling of hydrazine should be the last resort as a method of controlling worker exposure. In cases where respirators are needed, proper respirator selection and complete respiratory protection program consistent with OSHA guidelines should be implemented.

For USAF personnel, Air Force Occupational Safety and Health (AFOSH) Standard 48-8, Attachment 8 reviews considerations for occupational exposure to hydrazine in missile, aircraft and spacecraft systems. Specific guidance for exposure response includes mandatory emergency shower and eyewash stations and a process for decontaminating protective clothing. The guidance also assigns responsibilities and requirements for proper PPE, employee training, medical surveillance and emergency response. USAF bases requiring the use of hydrazine generally have specific base regulations governing local requirements for safe hydrazine use and emergency response.