Mining�s pain in the back

WHETHER with a shovel, a hammer or a heavy load, high numbers of low back problems and disorders have plagued the mining industry throughout history. Two NIOSH researchers examined ways to combat the pain in a presentation offered at the recent annual meeting of SME.

Donna Schmidt

“It is believed that the higher incidence of these injuries among miners is the result of high exposures to postural demands, heavy manual work and exposure to whole-body vibration,” noted Sean Gallagher and Alan Mayton of the National Institute for Occupational Safety and Health.

“There is mounting evidence that disc degeneration plays a large role in the development of low back pain, particularly chronic back pain.”

“Back injuries [in mining] are one of the highest in terms of workers compensation claims,” Gallagher added.

While the researchers note that back pain was previously thought to be a result of strain at the “trigger points” of the body, some modern research has pointed to several other factors including disc disruption and degeneration, which they said can account for up to 39% of those suffering pain.

Gallagher and Mayton said the disruption and degeneration of the spine begins when the vertebral endplate is compromised during whole-body vibration (WBV) or loading activities, resulting in a fracture where the body then creates scar tissue. That resulting tissue then prevents nutrient absorption, leading to degeneration and tears in the disc, which is measured in grades of progression.

It is important to note that an item’s weight is not the only factor to be realised with loading activities, according to the researchers. The amount of weight lifted must be multiplied by the distance from the body to determine the muscle force being used.

Additionally, the way in which something is lifted is important. Bending forward, Gallagher noted, can result in as much as three times the spine load as upright lifting of an object.

The best prevention in the end, said the researchers, is reducing the likelihood of endplate fracture. Using mechanical assist devices such as hoists can aid in that, as will the reduction of object weight when possible to reduce spine stress.

Seat design is also being examined for the factor of whole-body vibration, and actions workers can take to minimise pain and stress include reducing vibration impact, using proper alignment, using the adjustability of a seat, keeping unobstructed views, and allowing for maximum circulation and movement.

The researchers also suggested adjusting the layout of a facility, including identifying transportation issues and associated costs and examining supply handling systems. Some of the problem areas most often found, the two noted, include poor housekeeping, obstacles in the flow of materials, crowded conditions and cluttered entries.

In the area of research and development, specialised vehicles and mining tools are other areas of interest mentioned by Mayton and Gallagher. In fact, one such example is the “Zipmobile” – named for its miner developer – that rides on the handrails of a longwall conveyor to transport supplies.

Because not many tools are specifically designed for mining use, the development of specialised equipment often attracts attention. Such has been the case with the researchers’ other example, a tool developed to help remove conveyor belt rollers.

“It should be clear that many opportunities exist for reducing physical demands of mine workers through development, adaptation or use of mechanical assist devices in the mining environment,” the two said.

Because of the high percentage of injuries to individuals in the heavy-duty environment of a mine (statistics reflect as many as 77% of underground injuries are WBV related and occurring in the head, back and neck), the pains will continue to be a significant and costly problem unless operators and miners themselves take the initiative to minimise hazards.

“It may never be possible to completely eliminate back pain in the mining industry; however, there are many steps that can be taken to greatly mitigate the risk,” the researchers concluded.

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