Substance-Specific Issues

Coal, classification with respect to flammability and toxicity

Substance:

Coal (coke); CAS No. 65996-77-2

Issue:

Does coal fall within the flammability and / or toxicity criteria specified in the Controlled Products Regulations (CPR)?

Considerations:

Coal is a complex mixture as defined in CPR 2(1), i.e., a mixture that is a combination of many naturally occurring chemicals. As provided for by section 5 of the CPR, in the case of a controlled product comprised of 100% of a complex mixture (e.g. pure turpentine), the commonly known generic name for the complex mixture may be disclosed on the MSDS in lieu of the names of the individual ingredients of the complex mixture. As such, it may not be possible to determine classification based on the composition of the coal. Rather, the classification of coal would be based on the properties of the complex mixture and not on its individual components.

Inhalation of coal mine dust has been associated with the development of coal workers pneumoconiosis, emphysema, chronic bronchitis, and obstructive lung disease. These effects have not been observed in animal studies. Animal models did not demonstrate high direct toxicity following coal dust exposure. Animals also demonstrated little evidence of a fibrotic response after coal dust exposure. IARC had reviewed the toxicity of this product and came to the conclusion that coal dust cannot be classified as to its carcinogenicity to humans and assigned it a Group 3 designation [1-3].

In terms of flammability, the potential for this hazard is recognised but is more related to the process; i.e., it is influenced by the presence of coal dust and the co-presence of methane, a flammable gas. Therefore, it is the process, rather than the coal itself, that may present fire and explosion hazards. In addition, flammability could vary with the origin (geological characteristics) of the coal, the percentage of volatile matter, the calorific value which all have an impact on the ease of combustion [3, 4]. Some suppliers may have test results that indicate if their product meets or does not meet the flammability criteria specified in section 39 of the CPR.

Coal is not classified as a flammable solid under the Transportation of Dangerous Goods Regulations, (TDGR) [5]. The TDGR specify criteria similar to that of the CPR for a flammable solid. It should also be noted that different terminology or terms are used to describe compounds of this family. For example, charcoal and carbon (animal or vegetable origin) are classified as flammable solids (UN1361) under the TDGR. However, charcoal and carbon refer to something different from coal in terms of origin, composition and particle size.

Conclusions:

1. There is insufficient evidence to classify coal as a flammable solid.
   
   
2. Based on the chronic health effects observed in human (e.g. pneumoconiosis) and pursuant CPR 33(2), coal is considered to fall within the criteria for a material causing chronic toxic effects, i.e., it is included in Subdivision B of Division 2 of WHMIS Class D.

References:

1. Répertoire Toxicologique de la Commission de la santé et sécurité du travail, Québec.
   
   
2. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans; Volume 68, "Silica, Some Silicates, Coal Dust and para-Aramid Fibrils", 1997.
   
   
3. Patty's Toxicology, Fifth Edition, Volume 1, Edited by Eula Bingham, Barbara Cohrssen, and Charles H. Powell, Jonh Wiley & Sons 2001.
   
   
4. Kirk-Othmer Encyclopedia of Chemical Technology, Fourth Edition, Volume 6, John Wiley & Sons 1993.
   
   
5. Transportation of Dangerous Goods Regulations as published in the Canada Gazette Part II, SOR/2001-286, supplement to volume 135, August 15, 2001; (coming into force on August 15, 2002).