Abstract
The mining industry, currently undergoing profound changes, is destined to play an increasingly important economic role in the province of Quebec, Canada. Activity in this sector, its real net impact on government tax revenue, the economy, society, and the creation of wealth, is the subject of much discussion. Occupational health and safety is a major preoccupation in the mining sector, in which considerable numbers of workers suffer workplace accidents or occupational diseases due to the use of industrial chemicals, compounding the problem of exposure to noxious substances that exist naturally in mines or are produced inevitably in the course of normal mining operations. Air in mines thus can become laden with a wide variety of chemical agents, in the form of suspended solids, liquid droplets, and vapors and gases. Long-term exposure to most of these agents can seriously harm the health of mineworkers. Prevention remains the key to avoiding the social and economic consequences of these hazards and will make mining a more attractive sector for investment and employment in Canada.
The principal focus of this study, presented in two articles, is to set a preliminary theoretical framework for categorizing chemicals in terms of their effects on the health of mineworkers throughout the various phases of mining projects. The objective is to decrease (over the long term) the number of occupational diseases due to the use of chemicals by raising awareness among employers and exposed workers in the mining sector.
This research was conducted in four phases. The first article presented a review of the literature [1] on the chemical aspects of health and safety in mining in the province of Quebec. In the present article, the findings on the recurrence of health problems attributable to chemicals encountered in mines and how these effects should therefore be ranked from an occupational health and safety perspective are presented. The results show that various forms of dermatitis are the most recurrent health and safety risk.
1 Introduction
In 2018, the Quebec mining industry employed 17,909 persons directly or indirectly in some aspect of mineral extraction, up to and including mine shutdown and rehabilitation of sites [2]. Numerous chemical agents come into play during the initial process of transforming ores into saleable minerals. Most of the occupational diseases caused by these agents are not diagnosed early, and symptoms often are not apparent until after several years of exposure [3, 4].
Gases, vapors, dust, and smoke also can accumulate in mines and have harmful effects on the human body if inhaled at concentrations much higher (50 times higher may be lethal) than the safety limit, defined usually for 4 h of exposure [5]. However, the risk is seldom negligible at low concentrations and must be taken into consideration.
Chemical-associated OHS risks and potential health effects compiled previously [1] have been characterized for the chemical industry in general, using indexes such as short-term exposure and time-weighted average exposure limits, toxicological data, and the danger statement on each safety data sheet in the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) (GHS) [6]. The toxicity of a chemical depends on several factors, primarily the duration of exposure, the frequency of exposure and toxicological (concentration) data [7]. All toxic effects appear more markedly with longer exposure [8].
The Ontario occupational cancer research center estimates at 1,300 per year the number of cancers associated with exposure to asbestos, diesel motor exhaust or crystalline silica during work in mines [9]. Occupational diseases tend to have long latent periods and not to manifest themselves until long after exposure to the causal chemical agent [10]. This accounts for most of the indemnities paid out between 2008 and 2017 in the mining sector [11].
In Quebec, the number of occupational lesions related to chemicals in general is about 1,500 cases per year [12]. Of these, 326 were recorded in the mining sector during the years 2010–2012 [13]. The agents listed in our previous article [1] are the cause of afflictions of the skin and mucus membranes (irritation, eczema, etc.), the respiratory system (asthma, hypersensitivity pneumopathy, cancer, etc.), the nervous system (parkinsonian syndrome, etc.), kidneys, urinary bladder, liver (kidney failure, cancer, etc.), blood (anemia, leukemia, etc.), heart (cardiac arrhythmia, infarction, etc.) and circulatory system [14].
Some risk management tools have been used to attempt to lower occupational risks in the mining industry [15]. However, this practice is often limited and does not extend systematically to the use of chemicals or the generation of noxious chemical substances by mining activities.
Having reviewed the literature available on chemical hazards in the mining industry in Quebec [1], this paper presents the second part of the framework for defining in detail the consequences of exposure of workers throughout the various phases of mining projects, by focusing on the number of recurrences of harmful effects attributable to chemicals. A ranking of risk management is then proposed accordingly. The aim is to recommend ways of raising greater awareness among exposed workers and on the long-term to decrease the numbers of occupational disease cases in the industry.
The rest of this article is organized as follows: Section 2 provides a description of the research methodology used to attain the main goal of the study overall and of this article specifically. The results of the present research are presented in Section 3 and discussed in Section 4. Conclusions are presented in Section 5.
2 Methodology
The methodological approach features a theoretical framework presented previously [1] and a practical framework, presented here. The former consisted of listing the chemical agents known to have some negative impact on workers' health during each of the four phases of a mining project and identifying these effects, based on a review of the literature [1]. The practical aspect is also two-fold: ranking of occupational diseases according to their potential recurrence, and ranking of chemical agents according to their potential of risk (Fig. 1).
Methodological approach
Citation: International Review of Applied Sciences and Engineering 14, 1; 10.1556/1848.2022.00487
2.1 Ranking of occupational diseases according to their potential recurrence
This step consists of tallying recurrences of harmful effects on mineworkers potentially due to each of the chemicals listed in Table 1 through 4 in the previous article [1]. Standardization of the potential effects and the set of chemical agents are shown in Appendix (Table A1) in the form of contingency matrix K with q × m dimensions crossing variables X1 (potential occupational diseases) and X2 (chemical agent) having respectively q and m modalities observed.
Potential harmful effects of exposure to chemicals in mining
| Harm caused by exposure to the chemical | Potential effects on health (occupational disease) | Organs affected |
| Burns or irritates on contact | Dermatitis | Skin |
| Genetic anomalies or other afflictions following ingestion or inhalation | Kidney disease | Internal |
| Not immediately apparent physiological consequences | Cancer | Skin, internal |
| Respiratory distress or symptoms appearing later | Asthma | Lungs, trachea |
| Serious lesions or irritation | Fibrosis | Eyes, skin |
| Respiratory or visual difficulty, rash, carcinogenesis | Mesothelioma | Skin, lungs |
| Respiratory tract distress after inhalation, ingestion | Pulmonary disease | Lungs |
| Possibly fatal reactions when inhaled or in contact with skin | Silicosis | Nose, sinuses, eyes |
| Possibly fatal reactions when inhaled or in contact with skin, carcinogen | Asbestosis | Lungs |
The harmonized system safety code indicator (H…) refers to the risk associated with using a chemical in a mining operation during any of the four phases of a mining project. It defines the likelihood of the risk associated with an agent in the sample nj from the set of agents catalogued. Starting from this information, the risk inherent in each chemical is used also to define and rank an occupational disease based on the number ni of recurrences. This step provides the objective elements used to determine and analyze the research results presented in the next section.
2.2 Ranking of chemical agents according to their potential of risk
Ranking the OHS effects potentially attributable to chemicals provides an evaluation of the relative risk associated with each based on the combination of the intrinsic hazard level (gravity) and the intensity (frequency) of exposure. For this model, the hazard criterion is scored on a 4-level scale based on the harmonized system (GHS) statement (or mention) of health risk on safety data sheets, namely Sgh05, Sgh06, Sgh07, Sgh08. The exposure criterion is defined by the “H” code and the category of hazard.
The estimated level of risk is presented in Section 4 as results in matrix form with rows corresponding to hazard category. Table A1 shows the risk code determined according to the number of recurrences as a function of the standardized potential effects on health.
The catalogued chemicals are ranked using the 4-level qualitative health hazard scale: 4 = critical (Cat. 1, Cat. 1A/1B/1C), 3 = high (Cat. 2), 2 = moderate (Cat. 3), 1 = low (Cat. 4). The risk criterion for each chemical is chosen based on the maximal multiplication of the number of occupational diseases and the hazard level of the chemical agent.
3 Results
The potential harmful effects of chemicals encountered in mines are identified in Section 3.1 below. The number of recurrences of these effects and their ranking are given in Sections 3.2–3.4.
3.1 Identifying of the potential occupational diseases of chemicals on the health of mineworkers
The chemical agents catalogued previously [1] are recognized as potential health hazards in the workplace when they bear the mention “H” for hazards in their safety data sheet, in accordance to the GHS. Only 29 mentions of hazards (47% of all physical, health and environmental risks) listed in the safety data sheets are relevant to the present research work. These concern occupational diseases well known in the Quebec mining sector: acute toxicity, serious eye lesions, eye irritation, respiratory or skin sensitivity, mutagenicity, carcinogenicity, toxicity during production, specific toxicity targeting certain organs, danger of inhalation. Table 1 shows the occupational diseases resulting potentially from exposure to each chemical as a function of the mention of hazards on the safety data sheet.
3.2 Recurrences of the occupational diseases attributable to exposure to chemicals in mines
The potential effects of exposure of mineworkers to the chemicals listed previously [1] are based on title 9 (chemical property information) and title 11 (toxicological information) of the safety data sheet. The method used to calculate nj is also used to group chemical agents, safety data sheet information, occupational disease family, risk score and risk level in Table A1.
The numbers of recurrences of the occupational diseases defined in OHS and grouped by chemical agent are shown in Table 2.
Calculated recurrences of occupational diseases in mines
| Potential effects on health (occupational disease) | Total number of recurrences n(j) | % of recurrences |
| Dermatitis | 105 | 47.3 |
| Pulmonary disease | 46 | 20.72 |
| Asthma | 30 | 13.51 |
| Kidney disease | 17 | 7.66 |
| Cancer | 15 | 6.67 |
| Mesothelioma | 4 | 1.8 |
| Fibrosis | 2 | 0.9 |
| Silicosis | 2 | 0.9 |
| Asbestosis | 1 | 0.45 |
| Total | 222 | 100% |
3.3 Ranking of occupational diseases according to their potential recurrence
The relative significance of each of the 9 potential occupational diseases related to chemicals encountered in mining, based on the numbers of recurrences (Table 2 above), is represented graphically in Fig. 2 below.
Classification of occupational diseases according to their recurrence n(j)
Citation: International Review of Applied Sciences and Engineering 14, 1; 10.1556/1848.2022.00487
3.4 Ranking of chemical agents according to their potential of risk
Based on the potential occupational diseases determined above, the chemical agents can be ranked in decreasing order as a function of the safety data sheet H (hazard) status. Figure 3 (derived from Table A1) shows their grouping into 4 hazard categories or OHS priorities (category 1/1A/1B/1C critical, category 2 high, category 3 moderate, category 4 low). Figure 4 shows the ranking relative to the maximal risk score of each chemical listed in Table A1.
Chemicals agents and cleaning products used in the mining industry, categorized by health hazard
Citation: International Review of Applied Sciences and Engineering 14, 1; 10.1556/1848.2022.00487
Ranking of chemical agents according to their potential of risk (Rmax(i))
Citation: International Review of Applied Sciences and Engineering 14, 1; 10.1556/1848.2022.00487
4 Discussion
The results in this article are in fact based entirely on the exploratory analysis of the literature available on chemicals encountered by mineworkers in Quebec, occurring naturally or used in operations associated with one or more stages of mining projects [1], and on the health hazards they appear to represent, based on safety data sheets and statistics provided by the CNESST, the provincial compensation board.
4.1 Representativity of the repertory of chemical agents
The list of chemicals was derived from rational evaluation of mining practices without focusing on the details of the work environment in this sector [1]. Of the 85 chemicals used during at least one of the four stages of a mine lifecycle (exploration, development, extraction, and shutdown), 64 (80%) are not rated for short-term-exposure concentration limit, 48 (60%) are not rated for time-weighted average concentration limit, 4 (5%) are not associated with any specific harm and 3 (3.75%) have no health hazard mentioned in the harmonized system. The chemicals for which short-term exposure data are available are used during extraction (16%), development (15%), shutdown (11%), and exploration (9%). In the absence of specification of these tolerable exposure limits, especially acute toxicities, the OHS-defined harm associated with exposure to these substances cannot be verified.
4.2 Characteristics used to rank chemicals based on potential occupational diseases
Among the numerous agents to which mineworkers are exposed by inhalation are gaseous fallout from the use of explosives, diesel motor exhaust, smoke or dust produced by drilling, rock fractures and evacuation, metal refining, welding, and vapors from cleaning products. About 47% of the most recurrent harms representing occupational disease are dermatitis, followed by pulmonary disease (21%) and asthma-like syndromes (14%). Allergic contact dermatitis is enhanced by pre-existing skin conditions. Cuts, sores, and abrasions also facilitate the development of allergen-associated dermatitis. The grouping of these principal categories of occupational disease is only approximate, based on what was suggested by the data retrieved during this study. It should be noted that occupational disease risk factors can be controlled by technical means that employers are free to implement to reduce or prevent needless exposure of mineworkers to chemical hazards, including safe work methods, properly adapted ventilation systems and adequate monitoring of air quality, spills, and worksite cleanliness.
4.3 Characteristics used to rank chemicals as hazards
Safety data sheets, an essential decision aid tool, contain limited information but nonetheless sufficient for ranking chemical agents using a simplified method based on determining the number of recurrences of symptoms or conditions suggesting a health hazard, as shown in Table A1.
Using the number of recurrences and the H status, ranking of the chemicals in decreasing order allowed to define four families (Fig. 4), based on maximal hazard scores of 20–16, 15–12, 9–6, and 4–3, and each corresponding to a specific category of OHS-defined health hazard. The fourth family contains 50% of the chemical agents, these causing burns on the skin and serious lesions on the eyes of mineworkers. This finding and its implications are straightforward. Using a simple method and minimal information, a mining company can orient a prevention program and OHS strategies insofar as chemical agents are concerned. However, this method does not yet suggest how to reduce specific chemical risks.
4.4 Prevent occupational diseases
The prevention of occupational diseases caused by chemical agents is a difficult task and mines must tackle the source of the problem. Several researches recommend these measures [16, 17]:
- -Know the hazards in the workplace (e.g. learn about the products that are used, their hazards and the measures to protect yourself).
- -Develop (for employers) and adopt (for employees) systems, procedures, practices and programs that are designed to protect people from chemical hazards in the workplace.
- -Transmit all information concerning health hazards and exposure to employees. Provide appropriate training and information regarding the hazards that are present.
- -Work with health professionals to assess occupational illnesses that have characteristics indicating that they are likely in the workplace.
- -Keep a list of all jobs held and the sectors of activity in which workers may be exposed to chemical agents.
- -Review the conditions of employment.
- -Train workers and managers to make them aware of OHS legislation and regulations.
- -Offer OHS support for workers and managers.
- -Develop tools to facilitate their work (e.g. software to consult the worker's experience and the training courses followed before entrusting them with tasks).
- -Stay on standby to be able to replace chemical products with others that do not present any danger.
- -Provide individual and collective protective equipment and ensure their proper use and maintenance.
This list proposes the main lines and the mines must set up a fairly detailed prevention program. They can refer to the various occupational disease prevention programs in other activity sectors in Quebec, such as construction and manufacturing. It is clear that the involvement of an occupational physician is necessary in this preventive work.
4.5 Limitations of this research, and prospects
This portrait of the health risks associated with exposure to chemical agents encountered in mining, both those used in operations and those that occur naturally, remains incomplete. Among the limitations of this preliminary and exploratory study are the absence of mineralogical analysis of aerosols and discussion of specific methods of raising awareness among exposed workers and of lowering over the long term the risks of developing occupational diseases.
The evaluation of the chemical hazards was based mainly on safety data sheets, primarily the hazard symbol and associated statement, which was advantageous for our purposes. However, the incompleteness of the short-term and time-weighted average exposure concentration data was an obstacle to obtaining more detailed results. Analyses of field samples or workplaces in which multiple mining-related contaminants are present would have strengthened our study. It is nevertheless possible to compare in considerable detail product information available at supplier websites and occupational disease statistics to rank the risks thus identified. Future research could build on the present study, using the results presented here as a database in a project focused more on the management of chemical risks associated with mining activities, for example the design of risk ranking software.
5 Conclusion
This paper exposes the health risks associated with chemicals to which workers are exposed during mining operations in Quebec. The research began by reviewing the literature to compile a catalog of the chemical agents used or encountered naturally during at least one phase of the mining project lifecycle and to identify worker health conditions potentially due to this exposure, referring mainly to general harmonized system safety data sheets. The results of this review are published elsewhere [1]. Then sought to guide OHS priorities by ranking the potential effects of chemicals on the health of mineworkers as a function of their recurrence in claims for worker compensation. According to this objective ranking, dermatitis was the most frequent basis for claims, recurring 105 times, while the most problematic family of chemicals had a hazard score of 20.
Despite certain limitations, this research has contributed to the identification of strengths and deficiencies in the evaluation of chemical hazards. In view of the number of chemical agents encountered throughout the lifecycle of a mining project and their potential effects on worker health, the findings of this study reiterate the urgency of OHS research and field practice and suggest how these activities might be ranked.
Author Contributions
This paper is entirely based on the results of research conducted by Paul-Patrice Biyick as part of his master’s project in industrial safety and hygiene under the direction of Professors Adel Badri and François Gauthier. Adel Badri has written the paper in collaboration with Paul-Patrice Biyick and François Gauthier. All authors have read and agreed to the published version of the manuscript.
Funding
The authors thank the Université du Québec à Trois-Rivières (UQTR), Fonds de recherche du Québec - Société et culture (FRQSC) and Natural Sciences and Engineering Research Council of Canada (NSERC) for their financial support.
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Appendix
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