Safety Articles

Injection Injuries: Liquid Bullets

Injection injury -- even the phrase will make a grown man flinch. The airless spray equipment that makes your job easier can make your life quite painful if you don’t follow some simple safety precautions. Never treat an injection injury as a simple cut; you must treat it as though you had been shot with a poisonous bullet.

Airless spray equipment operates by forcing liquids at very high pressure through a very small, precise opening. Grease guns, spray guns, diesel injectors, paint guns, concrete guns, plastic injectors all operate with anywhere from 600 to 12,000 pounds per square inch (psi) velocity. This can drive the fluids you are spraying through your body tissue in excess of 600 feet per second if the nozzle is four inches or less from your body – about the velocity of a rifle.

The military uses the same general technique to administer their vaccinations without hypodermic needles. They just put the injection nozzle on your arm and fire. The velocity of the stream is so strong that the medication is atomized through your skin without breaking it. It’s not painless, but practical for the purposes of mass inoculation. The medical personnel administering the vaccinations are at risk of injection injury. Likewise, animal handlers can suffer injection injuries when vaccinating chicken and pig stock. Even fire-fighters have reported injection injuries from their high-powered water jets.

On coatings jobsites, these easily prevented injuries do occur, whether through accident, inattention, or poor work habits. Simple care and attention to detail will help keep you from becoming a statistic.

Looking at Statistics.

Injection injuries happen most commonly to men, ages 21 to 59, on a new job or using a new tool. That’s just about everyone at one time or another. Over 75 percent of injection injuries reported are to the index finger of the hand not holding the tool. The second most common injury site is the fleshy area below the thumb of the hand not holding the tool. The typical injury occurs with an entry point at the tip of the finger, but the velocity of the pressure can drive the injected substance from fingertip to palm, injuring the surrounding tissues and destroying blood vessels, similar to a gunshot wound.

Grease is the most commonly injected fluid, closely followed by paint. Oil-based paints cause more injury than water-based paints; however, both will cause rapid tissue death.

The number of injection injuries is difficult to assess, but a group at the University of Colorado estimated that 1 in 600 hand injuries treated in their emergency department were injection injuries.

There are several factors that determine the severity of the injury:

  • The type and amount of the liquid injected. A highly toxic material will have a more negative effect than a clean water injection
  • The temperature and viscosity of the material will also affect the injury
  • The injection velocity.
  • The time between injury and treatment.
  • The part of the body that is injured and whether the injected liquid was introduced into the bloodstream.


Treating Injection Injuries.

The injury site may appear to be only a small puncture wound with very little pain, often with a small amount of the fluid injected dripping out of the wound. Don’t mistake this rather unremarkable looking injury for anything less than an injury that can lead to amputation or even death.

Since the injected material acts as a projectile, there may also be a small exit wound. The amount of pain experienced at the time of injection is a very poor indicator of the extent of damage; within even a few hours of a paint or paint thinner injection, the injury site will grow in pain intensity as tenderness and discoloration of the skin start to occur. It may take a couple of days for other injected substances, such as grease, to start to cause this damage.

Prompt treatment of ANY injection injury is absolutely necessary. Typically, most patients with injection injuries report to the medical facility after their work day is complete and the injury site has started to swell and hurt. This delay can be critical to treatment.

It is important to tell the medical personnel treating you that you have suffered an injection injury, what substance you were working with, and the estimated velocity of the machine you were operating. According to Stan Stutzka of the California Poison Control System, “It’s not the injected substance that is critical, but the pressure at which it was injected. A toxin injected at a low pressure may not be as critical as water injected at an extremely high rate of pressure.”

In addition to information about the airless sprayers’ velocity, also bring the Material Safety Data Sheet (MSDS) for the injected coating. This will help the medical personnel to provide the correct treatment.

Some medical personnel may also be fooled by the small wound and not start the radical treatment necessary, so make sure that the treatment team understands injection injuries and their treatments. This type of injury should be considered a surgical emergency. If you suspect that you have suffered an injection injury, go immediately to a Hospital Emergency Room; NOT an Urgent Care or physician’s office.

The treatment may involve a tetanus shot if yours is not current, as well as a preliminary x-ray to see the area of injection and the amount of tissue already involved.

Since the injured tissue is susceptible to bacteria, an antibiotic is often prescribed to prevent secondary infections. The damaged tissue and injection material will be immediately removed under anesthesia, in a procedure called debridement.

The medical team may also need to decompress the injury area by cutting the skin areas open to relieve the swelling pressure and release the toxic chemicals injected. This can result in substantial wound areas. Further debriding may be necessary as the surrounding tissue becomes involved over the next couple of days. The medical team may also need to treat you for any acute reactions to the chemicals injected.

Amputation is often unavoidable, especially in injuries to the fingers. Paint and paint thinner cause the most amputations with estimates as high as 48 percent of these type injuries ending in amputation. Even if amputation is avoided, the finger or toe may be too stiff to be usable. Other complications can include infection, permanent contraction of the injured digit, and chronic pain. Physical and occupational therapy will be critical after the initial injury treatment to help restore as much use as possible to the injured area.

Even air or clean water injection injuries need treatment. Air injection will usually require antibiotics, splinting, and elevation of the injured area. Clean water injection will usually require debriding, antibiotics, and elevation of the injured area.

Prevention of Injection Injuries.

Prevention of this type injury is completely avoidable. Here are some simple rules:

  • NEVER point an airless sprayer towards your hand or body. Treat it as you would a loaded gun.
  • NEVER use your hand to stop a leak in the sprayer.
  • NEVER put your finger or hand in contact with the nozzle.
  • NEVER remove the safety spacer at the tip of the gun. This spacer is placed to reduce the possibility of injection through the skin.
  • NEVER spray in the vicinity of open flame, pilot lights, electrical outlets, or other sources of ignition.
  • NEVER allow hoses to become kinked, or to vibrate against rough or sharp surfaces
  • NEVER spray in an enclosed area without proper ventilation to remove vapors.
  • NEVER leave a spray unit that is pressurized unattended. The unit should be shut off, the pressure released, the trigger’s safety engaged, and the power shut off to the unit.


  • ALWAYS follow the coating and solvent manufacturers’ safety guidelines, as well as those of the spray equipment manufacturer.
  • ALWAYS wear gloves and goggles, but don’t count on these to “save” you.
  • ALWAYS use the correct-sized sprayer tip for the material being sprayed to prevent clogging.
  • ALWAYS inspect the hoses, connections, and fittings for signs of damage, and proper fit before using.
  • ALWAYS use approved grounded outlets and extension cords of the voltage and frequency noted on the motor.


Although these types of injuries are not common, according to the Fluid Power Safety Institute, “Over 99 percent of the people who service, repair, and troubleshoot hydraulic systems have been subject to the exact dynamics that trigger a high-pressure injection injury. However, the ‘liquid bullet’ either missed or deflected off its target.” That means just about everyone who uses an airless sprayer has created the perfect set of circumstances that could have led to this injury and the potential loss of limb.

If you have any questions regarding a possible injection injury, call the Poison Control Hotline at (800) 222-1222.

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