The International Agency for Research on Cancer (IARC) is a part of the United of the United Nations World Health Organization; one of IARC’s missions is to critically review medical and epidemiological studies and to determine from this information the likelihood that the chemical substances studied causes cancer. While IARC does not conduct medical research, its panel of international experts reviews the data and publishes its opinion in the IARC Monographs on the Evaluation of Carcinogenic Risk to Humans.

In the mid-1980's IARC reviewed the medical and research literature on exposure to crystalline silica; as a result of this, in 1987 they published Volume 42 of their monograph series. In that landmark report IARC concluded that crystalline silica is “probably carcinogenic to humans in exposure by inhalation”, and classified crystalline silica as Group 2A in their ranking of cancer risks. Ten years later IARC again reviewed the medical and epidemiological information on crystalline silica. Based on the more recent medical data published, IARC classified crystalline silica as a Group 1, human carcinogen; their highest risk rating. This finding was published in IARC’s Volume 68 in 1997.

The US Occupational Safety and Health Administration (OSHA) is required to react to information from credible sources like IARC in their efforts to reduce workplace hazards. Based on the IARC finding, OSHA’s Hazard Communication Standard (HCS) requires that products and materials containing 0.1 percent or more of crystalline silica be labeled with a cancer warning.

The identification of crystalline silica as a human carcinogen has initiated at least two activities. First, OSHA has indicated that it intends to significantly reduce the Permissible Exposure Limit (PEL) for crystalline silica. The PEL is the time weighted average amount of a material that cannot be legally exceeded for an 8-hour shift during a 40-hour week. The current PEL for crystalline silica (quartz) is:

10 mg/m³ / (SiO₂^* + 2)
^* this is the percent of crystalline silica in the product.

For example if a material is 100 percent crystalline silica the formula is:

10 mg/m³ / (100 + 2) = 0.1 mg/m³

This means that workers using crystalline silica products cannot be exposed to more than 0.1 mg/m³ of crystalline silica in 8 hours. This is a very small amount of material.

OSHA believes that the current PEL still exposes workers to a significant risk of silicosis and lung cancer and intends to reduce the limit. It is expected that OSHA will publish a proposed rule to regulate silica in the workplace in 2000, and that the PEL will be much lower than it is now. It is very clear, we will see tighter regulation of the exposure to crystalline silica and most likely stricter enforcement.

The second effect of crystalline silica being identified and regulated as a human carcinogen is the increased risk, cost and liability of litigation. There is a very active effort on the part of trial attorneys to sue manufacturers for real or perceived damages caused by their products or raw materials used in making their products. Recent examples of this are the asbestos litigations, which are still on going many years after the use of asbestos has essentially ceased, and the lead paint class action suits. These kinds of litigation are tremendously expensive to defend against and devastating if found liable. There are some law firms seeking these types of cases for crystalline silica exposure.

With the findings of IARC and the acceptance of them by OSHA, the hazards of using crystalline silica are clear and well established. The continued use of crystalline silica in light of its known carcinogenic hazard is an unnecessary health and business risk when there are effective substitutes that are free of detectable respirable crystalline silica.

Contact CR Minerals Company, LLC today to find out how our SafSil ^®and Navajo Brand^® products can reduce the crystalline silica risks for your company.