What Diseases Can Silica Dust Cause?
The harmful effects of silica exposure on human health were first documented in 1700 by Dr. Bernardino Ramazzini, who observed symptoms of silicosis in stone cutters. Silicosis is the most common disease among people who underwent occupational silica exposure. Every year, there are between 3,600 and 7,300 new cases in the United States. The latency period of silicosis is different for each individual. Accordingly, the disease may develop within a few weeks to several decades after one breathes in silica dust.
In the early phase, silicosis produces damage to the air sacs of the lungs, which gradually gives way to fluid buildup (medically known as pleural effusion) and tissue scarring. Progressive massive fibrosis might also occur in severe cases, a condition which hinders breathing tremendously by causing extensive lung stiffening. Because silicosis reduces the amount of oxygen the body receives and affects lung capacity to a great extent, people suffering from this disease experience symptoms such as fatigue, weight loss, wheezing, a chronic cough, shortness of breath, chest pain, and loss of appetite.
There are 3 types of silicosis, each developing at a different pace:
- Chronic silicosis, which typically occurs as a consequence of 15-20 years of exposure to moderate concentrations of silica dust. Swelling gradually develops in the lungs, as well as in the chest lymph nodes. Initially asymptomatic, the disease causes increasingly distressing symptoms as it progresses, such as extreme shortness of breath, fatigue, and respiratory failure.
- Accelerated silicosis. It ensues following 5-10 years of heavy silica dust inhalation. The individual experiences symptoms, which include fatigue and severe shortness of breath, sooner than in the case of chronic silicosis.
- Acute silicosis, which develops within a few months to 2 years after exposure to extremely high concentrations of airborne silica. It has a more aggressive progress than accelerated silicosis, entailing very debilitating symptoms like disabling shortness of breath and often resulting in death.
Suffering from silicosis, regardless of type, increases the risk of developing a secondary lung disease at some point in the future, such as chronic bronchitis, lung cancer, and tuberculosis. Unfortunately, there is no cure for silicosis, but the disease can be effectively kept under control with the aid of medication and oxygen therapy. Due to the enforcement of better workplace regulations, the annual number of silicosis victims in the U.S. declined from 1,065 to 165 between 1968 and 2004. Nowadays, the illness is responsible for the death of approximately 100 Americans every year.
In addition to silicosis, exposure to airborne silica is also responsible for the following diseases:
- lung cancer
- kidney disease
- autoimmune diseases such as scleroderma, lupus, and vasculitis
What Are the Most Common Silica-Containing Products?
Because the construction industry is the primary employer of silica, the vast majority of products which contain it are building materials. Some of the most common silica-containing products in this category are:
- clay and ceramic tiles
- stone (limestone, granite, slate etc.)
- refractory castables
- roof tiles
- soil (top soil, fill dirt, soil with fly ash)
- certain paints
Silica exposure from handling building materials primarily affects construction workers. The general population, however, comes in contact with silica primarily by using the following consumer products, which contain it:
- art clays and glazes
- pet litter
- talcum powder
- household abrasives
Who Is Most Likely to Develop a Disease as a Result of Silica Exposure?
As is the case of asbestos, there is no safe amount of silica dust. Silica is a carcinogenic agent whose hazardous nature has been recognized by multiple reputable health agencies worldwide. Nevertheless, the duration of exposure and the amount of airborne particles are once again factors which play a key role in estimating the risk of developing a disease. People who were in direct contact with high concentrations of silica dust for several years are significantly more likely to be affected than those who underwent short-term exposure. Accordingly, silica exposure which occurs in the workplace is by far the most dangerous.
The following industries and activities entail a high risk if workers are not constantly wearing protective equipment while handling silica-containing materials:
- construction industry (masonry, sandblasting, jack hammering etc.)
- stone cutting
- mining (drilling through or cutting granite or sandstone)
- shipbuilding (abrasive blasting)
- glass manufacturing
- foundry work (moldings, shakeout, grinding etc.)
- pottery industry
- railroad (setting and laying tracks)
- jewelry production
- china and ceramic manufacturing
- hydraulic fracturing for gas and oil
- steel industry
- refractory installation and repair
- soap and detergent manufacturing
At the moment, silica dust is present in approximately 676,000 workplaces in the U.S. The most perilous activity, which releases enormous amounts of crystalline silica in the air, is abrasive blasting. It is performed with multiple purposes, such as to clean and smooth irregularities from jewelry, foundry castings, and molds, to etch glass, to finish tombstones, as well as to remove oil, paint, or rust from objects which are to be restored. Exposure from consumer products is unlikely to result in a disease. Nonetheless, since it remains a carcinogenic agent, regardless of the amount in which it exists, it is better to avoid silica as much as possible and opt for silica-free products instead.
Are There Any Workplace Regulations Concerning Silica Exposure?
Yes. In fact, because the previous permissible silica exposure limit for occupational settings, which became effective 45 years ago, was outdated and inconsistent with contemporary study results stating that even low-level exposure to silica dust can result in serious diseases, OSHA has recently issued a new one. Thus, the permissible limit is now set at 50 micrograms of airborne silica per cubic meter of air, averaged over a period of eight hours. By virtue of OSHA’s new rule, officially known as 29 CFR 1926.55(a), workers in the general industry will be exposed to 50% less silica, whereas those in the construction and maritime industries will inhale 80% less toxic dust on the job.
According to OSHA, the new silica rule is going to spare over 600 lives and prevent approximately 900 new silicosis cases every year. While the rule took effect on June 23, 2016, the industries it targets have one to five years to comply with the requirements, as follows:
- construction – September 23, 2017, one year after enforcement
- general and maritime – June 23, 2018, two years after enforcement
- hydraulic fracturing – June 23, 2018, with the exception of Engineering Controls, whose compliance date is June 23, 2021, five years after enforcement