The majority of workers in the trades know to wear earplugs or ear muffs when working in noisy environments, but what of the other benefits? Most welders know to wear a full face mask to protect their eyes and face but often neglect the ears.
Hot Slag Injuries
A ‘hot slag injury’ or ‘drop weld injury’ is a risk unique to welders who often find themselves working in awkward positions whereby the hot slag fragment can fall into the ear canal and cause significant pain and damage. If it reaches the eardrum it can produce a hole and potentially lead to lifelong problems.
A hole in the eardrum caused by a hot slag injury is a peculiar type of injury often associated with chronic drainage of the affected ear due to the damage to the lining of the middle ear and the body’s reaction to produce chronic drainage. The fragment itself can get stuck in the middle ear irritating the lining and causing further drainage.
This specific type of injury is also known to ENT surgeons because the hole frequently does not close on its own or just chronically drains. Surgically, the wound is very difficult to close as the surrounding tissue is often injured and will not support the graft used to close it. The other challenge the surgeon faces is ensuring that there are no metallic foreign bodies retained in the middle ear which can cause chronic infection and further damage other structures, such as the facial nerve, ossicular chain [the bones in the middle ear], or the inner ear, causing dizziness, hearing loss, and ringing in the ears. Upon entering the ear, the hot slag can even land near the carotid artery! The facial nerve and carotid artery, deep in the middle ear, are sometimes separated only by a thin plate of bone or in some instances, no bone at all. Who knew that a hot slag entering the ear canal could actually burn through the eardrum and enter the middle ear and then sit so close to a critical structure such as the facial nerve or carotid artery!
Another important point is that ferromagnetic foreign bodies, such as hot slags from welding, have the potential to move when exposed to the magnetic field of an MRI scanner. MRI scans are now in widespread use in medicine so any individual has a significant probability of having an MRI at some point during his or her life. We know ferromagnetic foreign bodies in the eye have moved during an MRI with reported cases of subsequent blindness. Having an MRI performed with a retained metallic foreign body in the middle ear could potentially damage nearby structures such as the eardrum, ossicular chain (bones in the middle ear), facial nerve or even the nearby carotid.
The good news is that hot slag injuries are easily preventable by simply wearing fire-resistant foam or silicone custom-molded earplugs, or ear muffs while welding. Since grinding often precedes the welding job, hearing protection is required anyway. Newer welding masks cover the ears as well as the face. A cloth welder’s cap can be used to cover the ears and neck for added protection.
Article by: Navin Prinja MD, FRCSC