Don’t Forget The Threat Of Heavy Metals
Safety article by Harold Hough
When we think of mine safety, we think of heavy machinery accidents, rock falls, and silicosis. However, there are equally threatening, but less visible problems according to occupational health experts. According to them, the hazards caused by heavy metals are often underestimated because they don’t cause immediate problems, but lead to long term health problems and even cancer. And, they threaten a long term liability in this law suit crazy era.
According to Dr. Kosnett, who consults with many major mining companies, some of the most common hazardous metal compounds found in mining are arsenic, lead, mercury, and cadmium. Nor is the threat just to miners. Mercury, for example is released into the air as a vapor from tailings, effecting above ground workers and even administrative personnel.
Here’s a brief description of some of the major threats that can be found around a mine site.
MERCURY. Mercury and mining have been intertwined for centuries. Not only was it used to refine gold and silver, it’s often found in ore deposits and old tailings. During the Comstock Lode mining era from 1860 to 1895, 15 million pounds of mercury were lost in the Carson River. In cases of massive mercury poisoning, the subject can become irrational, which gave us the expression, “mad as a hatter,” because hatters used mercury.
The biggest mercury threat to miners today is found in the ore as traces of cinnabar. Since it vaporizes at normal temperatures, miners don’t have to be around the dust to be exposed. Serious exposure can occur at the mill, in offices, and near tailings.
ARSENIC. Most people equate arsenic with murder mysteries. You know, the stuff that the butler uses. However, it is common in mines and provides both long and short term problems. Arsenic is usually found in mines as the compound arsenopyrite, realgar, or orpiment. Their risk as a poison is reduced somewhat because they aren’t soluble in water, but they pose a long term cancer risk, especially lung cancer if inhaled. When they are ingested, they are associated with an increased risk of bladder, kidney, liver, and skin cancer.
LEAD. Not only is lead found in many gold and silver operations, lead oxide is still used in fire assay for precious metals. Although this wasn’t even considered a problem until about 15 years ago, studies showed that assayers had high levels of lead in their bloodstream.
CADMIUM. This is often found in the mining and refining of zinc, and copper. Acute cadmium poisoning usually occurs by inhaling its fumes and may be a source of lung and prostrate cancer.
Unlike some poisons, the body can’t quickly rid itself of cadmium because it bonds with metallothionein, especially in the kidneys and liver. Consequently, it may take ten to thirty years to rid the body of half the cadmium ingested.
PREVENTING HEAVY METAL POISENING
Although these metals can cause immediate health problems, many of the risks are long term. As a result, mines should set strict standards for exposure, use equipment to limit exposure to them, and monitor the workers health on a regular basis.
According to experts, the first line of defense is to lower contact with good ventilation. If ventilation isn’t adequate, respirators are recommended. If skin contact is a risk, gloves and adequate clothing should be worn.
One way to monitor the situation is through urine or blood samples. However, these aren’t perfect because some non-toxic arsenic compounds found in seafood can elevate levels. Nor do they detect arsenic found in the lungs. As a result, effective monitoring can’t be limited to occasional testing.
Another way to monitor the site is to install air monitors throughout the site. These devices pump air through a filter where the particulate mater can be monitored. Of course, these monitors are stationary, while workers move around. This means that, as a worker moves through the site, the level of exposure changes. Consequently, personal air monitors clipped to a worker’s clothing are more accurate, although the cost of the monitoring program is much higher.
Although it’s easy to dismiss heavy metal exposure because its results aren’t as dramatic as an accident, mines can’t dismiss them. Even if you follow the MSHA or OSHA standards, recent studies show that they may not be enough. The smart thing to do is to aggressively monitor and avoid heavy metal poisoning threats in the first place.