What is Diborane Toxicity?
Diborane, also known as boroethane and boron hydride, is a colorless gas with a strong, sweet smell. Appearing as a gas in regular room temperature conditions, you can start to smell diborane when it reaches around 2 to 4 parts per million (ppm) in the air. In contact with water, diborane reacts quickly to produce boric acid and hydrogen gas in a powerful reaction. It dissolves easily in a substance like ether. Exposed to a spark, diborane can explode in air at concentrations between 2% to 25%, with explosions becoming more violent at concentrations of 10% and beyond. Diborane has properties that allow it to burn in air, producing boron trioxide and water.
Diborane reacts the way it does because of its structural instability. It has two hydrogen atoms forming two bonds in a tight ring with two boron atoms. Uses for diborane include acting as rocket fuel, an agent for chemical reactions, a processor for rubber, an element for electronic semiconductors, a catalyst for producing hydrogen, and an accelerator for the speed of flames. Fortunately, cases of toxic exposure to diborane are extremely rare due to its limited uses and difficulties in handling.
Diborane is legally recognized as an occupational and environmental toxin and is included on the Right-to-Know Hazardous Substance List. Strict limits are set for its exposure in the workplace, with a permissible limit of just 0.1 ppm over an 8-hour work day. Unique identification numbers are used to regulate diborane for safety purposes, such as its Chemical Abstracts Service number (CAS number), Right-to-Know substance number (RTK substance number), and Department of Transportation number (DOT number).
To identify hazards quickly and easily in emergency situations, the system called the NFPA 704 Diamond is used. This is a diamond shape divided into four colored sections, each representing a different hazard: health (blue), flammability (red), reactivity or instability (yellow), and other special hazards (white). For diborane, the NFPA 704 Diamond indicates a high level of risk in all categories, emphasizing its extreme toxicity, flammability, and reactivity. This information helps emergency personnel and individuals working with diborane to evaluate possible risks and take necessary precautions swiftly.
What Causes Diborane Toxicity?
Diborane gas is a potentially dangerous substance that is used in making electronics, rocket fuels, and by chemical labs. This gas has an explosive nature, and it’s irritating so it needs to be stored and transported carefully. Diborane should be kept in special containers made of stainless steel or commercial steel at extremely cold temperatures of -20 degrees Celsius or -4 degrees Fahrenheit.
There are certain materials like stainless steel, lead, Monel, copper, brass, paraffin, Glyptol, and Kel-F that aren’t harmed when they come into contact with diborane gas. However, it’s essential to note that natural rubber is rapidly destroyed when it comes into contact with diborane.
Because of the dangers posed by this gas, anyone handling diborane gas should always wear personal protective gear. This includes an air-supplied respirator with a full-face piece that has approval from the National Institute for Occupational Safety and Health. It’s also important to ensure good ventilation while working with diborane since it’s hazardous stuff.
If you need to handle this chemical, make sure to protect your skin by wearing gloves made of plastic, butyl, or rubber. You should also wear protective clothing such as Tychem® BR, LV, Responder, or TK, especially if you’ll be exposed to the gas for less than an hour.
Risk Factors and Frequency for Diborane Toxicity
Exposure to diborane gas is a rare occurrence and therefore, the exact number of incidences hasn’t been established. However, certain individuals are at a higher risk of exposure, including laboratory workers handling this chemical, workers in the microelectronics and rocket fuel manufacturing industries, and environmental cleanup crews. Although rare, exposure may happen during environmental cleanups ordered by the Environmental Protection Agency. It’s also important to note, diborane gas has been found at a minimum of three places within the 1,585 sites marked as National Priorities by the Environmental Protection Agency.
Signs and Symptoms of Diborane Toxicity
Those who already have health conditions could have severe reactions if they come into contact with a chemical called diborane, and their health can worsen rapidly. As such, healthcare teams need to be prepared to act fast and prioritize stabilizing the patient’s vital functions like breathing and heart rate. A thorough examination and review can then take place once the patient is stable.
Patients usually report potential exposure to diborane, often describing it as an unknown gas with a “sickly sweet odor.” The symptoms and how serious they are can vary, depending on how much of the chemical the person was exposed to and for how long. If someone has been exposed to diborane acutely, they may experience:
- Burns to the skin or mucus membranes
- Tightness in the chest
- Pain in the diaphragm (a muscle involved in breathing)
- Difficulty breathing, coughing and wheezing
- Dizziness and headaches
- Weakness
- Depression of the central nervous system
- Incoordination
Exposure to lower levels of diborane over a long period, known as chronic exposure, can lead to symptoms like:
- Irritation of the lungs
- Seizures and convulsions
- Fatigue and drowsiness
- Confusion
- Changes in brainwave patterns recorded on an electroencephalogram
- Involuntary muscle spasms
- Less common symptoms like headaches, vertigo, fever, and chills
During a physical examination, doctors may observe signs of breathing difficulty. These can include strained or noisy breathing, rapid breathing, decreased breath sounds, and crackling noises. Other symptoms unrelated to breathing that can appear include low blood pressure, irregular heartbeat, and symptoms of central nervous system depression such as seizures, excessive sleepiness, or even coma. The skin and mucus membranes should be examined to look for signs of burns or frostbite.
Testing for Diborane Toxicity
When someone is suspected of being exposed to diborane, a type of chemical, they might show specific symptoms. These might include problems with their lungs, especially if they already have a lung disease or are prone to lung infections. They would need to be closely monitored, with their heart rate and vital signs tracked, possibly along with additional oxygen.
If there are several patients exposed to diborane, the ones with the most severe symptoms should be taken to a hospital immediately. Severe symptoms can include continuous coughing, difficulty breathing, chemical burns, trouble protecting the airway, and other signs of diborane exposure. Patients with minor symptoms, such as temporary eye irritation or a sore throat, may be allowed to go home after being checked out and watched for a bit. Hospital personnel are not likely to become contaminated by taking care of diborane-exposed patients.
Even though specific tests are not needed to confirm the presence of this chemical exposure, they can be helpful. These tests might include a complete blood count, glucose levels, checking the metabolic activity, arterial blood gases, and a urinalysis. This could help to identify the seriousness of organ damage and rule out other conditions. Depending on the combined results of the urinalysis and the metabolic tests, kidney health could be assessed.
Additionally, chest radiography and an EKG (electric heart test) might be used to examine the overall health of the heart and lungs. Radiography might show unusual patterns in both lungs, and an EKG could determine if more heart tests are necessary.
Treatment Options for Diborane Toxicity
If someone is exposed to diborane, they should be quickly moved away from the exposure source and washed with saline solution. A chemical filter mask with Hopcalite can be used for temporary protection.
Unfortunately, there’s no specific antidote for poisoning by diborane, and treatment mainly focuses on managing the symptoms; for example, extra oxygen can be given to those experiencing breathing issues. Some patients with severe difficulty in breathing or reduced consciousness may require a tube to be inserted into their windpipe and assistance with breathing.
Burn-type injuries to the airways can lead to swelling that may block the airways. In children, a medicine mist called racemic epinephrine can be used if they start to develop breathing sounds known as stridor. Inhaled and intravenous steroids have been found to aid in lung recovery in cases of poisonings similar to diborane. Adults experiencing bronchospasm, or narrowing of the airways, may benefit from breathing in a medicine called albuterol.
For patients who become unconscious, have low blood pressure, or are having seizures, they should be treated following advanced life support guidelines. Adult patients with shock should be given fluids at a rate of 1000 mL/h. For children in shock, they should receive a quick initial fluid bolus, followed by a slower infusion. Patients with signs of serious burns or lung injury, such as ongoing shortness of breath, violent coughing, or feeling of chest tightness, should be admitted to the hospital until the symptoms resolve.
For those with minor exposure to diborane, their symptoms should clear up within an hour. They can be discharged from observation a few hours after their symptoms have disappeared to make sure no delayed effects are missed. It’s important to note that diborane-related symptoms may be delayed up to 24 hours due to the chemical’s high ability to dissolve in fats. Follow-up after discharge is recommended due to the potential for long-term breathing issues after inhaling diborane. Patients with skin and eye injuries must be reexamined within 24 hours.
What else can Diborane Toxicity be?
When trying to identify the cause of sudden shortness of breath, doctors might consider the following conditions:
- A sudden worsening of asthma symptoms
- An extreme allergic reaction known as anaphylaxis
- Heart problems, like a sudden heart attack
- A sudden lung infection, also known as acute pneumonia
- Pneumothorax, where air leaks into the space between your lung and chest wall
- Exposure to any harmful gases such as chlorine, sulfur dioxide, or ammonia among others
However, the chemical diborane has a distinctive smell and may be identified by those exposed to it, leading to its identification as the cause of the breathing difficulties. In addition to this, diborane is strictly controlled and only available in a few places, which can also help in specifically identifying it as the cause. Another clue that can aid in this diagnosis is if there is also evidence of skin or mucous membrane damage on other parts of the body.
What to expect with Diborane Toxicity
The future health outcome of a person exposed to diborane, a type of chemical, largely depends on how much they were exposed to and for how long. However, in most cases, patients are likely to survive and recover with little to no complications. That being said, those with existing lung diseases or heavy exposure tend to have a less positive outlook. Smokers, too, are more likely to experience health problems as a result of diborane exposure.
Possible Complications When Diagnosed with Diborane Toxicity
After an illness, a patient may experience complications that relate to their lungs. These complications could be mild or severe, and both could affect how well a person can breathe and function. Mild complications can include a prolonged cough, weak respiratory muscles, inflammation in the upper part of the airway, delayed lung swelling, lingering difficulty breathing due to psychological factors, and reactive airway dysfunction (which involves bronchial tubes overreacting to irritants).
Severe complications can be serious and long-lasting. These could include conditions such as bronchiectasis (damaged and dilated bronchial tubes), chronic airflow obstruction (blocking of the airway), bronchial hyperreactivity (bronchial tubes that react in an exaggerated way to stimuli), bronchiolitis obliterans (a rare and life-threatening form of non-reversible obstructive lung disease), and hemorrhagic pneumonitis (inflammation of the lungs).
It’s recommended that patients showing signs of these lung complications see a pulmonologist, a doctor who specializes in lung conditions, for ongoing care and management.
Common complications could include:
- Prolonged cough
- Weak respiratory muscles
- Inflammation in the upper part of the airway
- Delayed lung swelling
- Lingering difficulty breathing due to psychological factors
- Reactive airway dysfunction
- Bronchiectasis (damaged and dilated bronchial tubes)
- Chronic airflow obstruction (blocking of the airway)
- Bronchial hyperreactivity (bronchial tubes that react in an exaggerated way to stimuli)
- Bronchiolitis obliterans (a rare and life-threatening form of non-reversible obstructive lung disease)
- Hemorrhagic pneumonitis (inflammation of the lungs).
Preventing Diborane Toxicity
It’s important to be very careful when handling diborane. This substance should only be stored and used in areas that are dry and have good air circulation. When storing and moving diborane, make sure it’s in the right kind of container and that it’s clearly labelled. Always wear the right safety gear to protect yourself.
