Exploding Insoles and Other Uncommon Causes of Burns

It’s winter and people are wearing heated clothing. Everything – from gloves to vests and socks – are outfitted with compact lithium batteries that activate micro coils woven into the fabric to warm you up. One popular item is the heated insole that goes into boots or shoes. The problem is, in some cases, the batteries in the insoles overheat, ignite and burn through the socks and skin of the person wearing them, causing severe burns.

This is one of the unusual cases that Daniel Lozano, MD, Chief, Department of Surgery with the Regional Burn Center at Lehigh Valley Institute for Surgical Excellence, part of Jefferson Health, encounters. 

This type of burn can happen with any number of electronic devices including vapes, drones and cellphones. Especially when using cheaply manufactured brands, they can end up exploding on some part of the body. And the burns they cause can be more serious than those from fire or hot liquid.

“Third-degree burns can happen at 156 degrees, but a failed electronic device burns even hotter,” Dr. Lozano says. “In the case of insoles, they stay in contact with the skin longer because they’re trapped in shoes. So, these lithium-related burns almost always require surgery.”

Dr. Lozano says lithium battery burns may also cause loss of fingers, toes and feet. The contact is lengthy enough for the burn to reach bones and tendons, which cannot be reconstructed. On the positive side, these burns are often restricted to a small area. So, while the burn is significant in that area, there isn’t a large surface affected. On large skin surfaces, burns are more life-threatening.

Treatment commonly starts with a skin graft and is always a challenging surgery. Dead tissue must be shaved away and new skin – usually taken from the thigh – is grafted onto the burn site. The site is watched to make sure blood supply is getting to the grafted skin.

Recovery from an insole burn can take up to 10 weeks, until the skin is thick enough to walk on. “Unfortunately, the skin on the soles of the feet cannot be fully recreated,” Dr. Lozano says. “There can also be lasting issues of sensitivity and durability. This can impact a person’s ability to work, enjoy activities and even drive.” 

Dr. Lozano says, to avoid this type of burn, choose good shoes and socks and consider chemical inserts, which aren’t battery powered. However, a note of caution: Chemical insoles warm toes with ingredients that react with oxygen in the air. Under normal circumstances, the insoles’ temperature stays in a comfortable range. But if they are worn in ventilated shoes – like sneakers – oxygen continues to react with the ingredients, driving the temperature to dangerous levels.

The Regional Burn Center, the only center in northeastern Pennsylvania verified by the American Burn Association and American College of Surgeons, specializes in all types of burns. The psychological toll is a big part of the care provided at the Walter J. and June H. Okunski Burn Recovery Center, closely affiliated with the Burn Center.

Experts there see many burns, including those from causes you may not think about. They urge awareness about the following: 

Acetylene: Regulations are in place for using oxyacetylene welding torches, but burns have been reported from inflating toy balloons with acetylene gas. It’s explosive and can reach 5,000° F. 

Airbags: Burns sometimes occur from airbag deployment. Causes include high temperature gases, friction and chemical burns from particulate materials and alkaline corrosives. 

Chemicals: Strong acids, drain cleaners, paint thinner, gasoline and other substances can cause tissue damage. People should seek emergency help if a chemical burn is larger than 3 inches, involves all layers of the skin and covers hands, feet, face, groin or a major joint. 

Dry ice: Because dry ice is about 100 times colder than a household freezer, it can cause severe injuries if it comes into direct contact with skin. Burns from dry ice, like frostbite injuries, occur quickly and can be painful and dangerous if not properly treated. 

Electrical current: When an electrical current touches or travels through you, it can damage cells inside your body. Electrical burns happen through accidental shocks from power lines; working with damaged appliances or frayed cables, wires or cords; and even from carrying batteries in your pocket with other items that electricity travels through easily, like keys or coins.

Frostbite: Your skin can become damaged from prolonged exposure to temperatures below 32° F. It can lead to permanent, irreversible damage when the cells in your tissue die.   

Immersion: Prolonged exposure to liquids, such as warm bath water, can cause burns, especially in infants or the elderly. (This is somewhat related to toasted skin syndrome, where skin is exposed to low-grade heat for an extended period – such as with a heating pad. This can cause discoloration of the skin that can be permanent depending on the length of exposure.)

Personal care products: Hair dye and bleach can cause scalp and skin burns, and acetone-based nail polish remover results in chemical burns if used too often or left on too long. Toothpaste containing hydrogen peroxide can burn skin and gums if used excessively. 

Radiation: Beyond sunburn, accidental exposure to X-rays or industrial radiation sources can cause significant damage.

Steam: While dry heat causes burns, wet heat scalds skin. Even a very serious scalding burn may be relatively painless when it first occurs.

Ultraviolet radiation: Ultraviolet radiation from the sun and from tanning beds is harmful. The rays penetrate the skin and can cause severe sunburn as well as aging and DNA damage. 

Warnings:

The U.S. Consumer Product Safety Commission (CPSC) has issued a public warning to immediately stop using certain brands of heated insoles. 

It’s important to note that defective lithium-ion batteries must be disposed of differently than other batteries, because they present a greater risk for fire. Do not throw a defective lithium-ion battery or device in the trash. Before taking your battery or device to a household hazardous waste collection center, contact the center ahead of time and ask whether it accepts defective lithium-ion batteries. If it does not, contact your municipality for further guidance.