Chemical-related injuries and 


illnesses in U.S. mining
 

D.F. SCOTT, E.M. MERRITT, A.L. MILLER 

AND P.L. DRAKE 

D.F. Scott, member SME, E.M. Merritt, A.L. Miller and 

P.L. Drake are research physical scientist, a former NIOSH 

intern, mechanical engineer and branch chieg, prevention of 

hazardous exposures, respectively, with the National Institute for 

Occupational Safety and Health, Spokane Research Laboratory 

(NIOSH-SRL), Spokane, WA. 

Abstract

The purpose of this study was to determine if miners were 

at risk from exposures to chemicals used in the mining 

industry and determine the nature and sources of the 

illnesses and injuries. The U.S. Mine Safety and Health 

Administration’s (MSHA) employment and accident, injury and illness database was reviewed.There were 2,705 

cases of chemical-related injuries and illnesses reported 

from 1999 through 2006, involving 66 different chemicals. 

The main source (cause) of chemical-related cases was 

acids/alkalis (about 39%). The primary nature (effect) 

of chemical-related cases was chemical burns (about 

57%). The job classification where workers incurred the 

most chemical-related injuries and illnesses was cleaning 

plant operator/media operator/boney preparation plant 

operator/crusher worker (cleaning plant operators are 

responsible for maintenance of plants, media operators 

are responsible for handling reagents, boney preparation 

plant operators oversee removal of “bone” from coal, 

and crusher workers use large crushers to break mined 

material). From 1999 through 2006, the rate of “nonfatal 

days lost” and “no days lost” (resulting from injuries) 

did not change significantly; however, the rate of illnesses 

decreased significantly. Chemical burns accounted for 

a large number of injuries; mining companies should 

carefully examine their personal protective equipment 

(PPE) requirements, training methods and safety culture 

to ensure that their workers are protected. 

Introduction

Thousands of miners are routinely exposed to a variety of chemical 

hazards. With nearly 329,000 operators and contractors working in the 

mining industry in 2006 (U.S. Dept. 

of Labor, 2007a), the potential for 

chemical-related illness and injury is 

high. In a recently published review 

of the occupational health hazards 

associated with mining, a variety 

of chemical hazards were assessed 

(Donoghue, 2004). The predominant 

hazards identified were exposure to 

silica, coal dust, asbestos and diesel particulate matter. 

Other noted health risks included exposure to arsenic, 

nickel, lead, cadmium, manganese, 

platinum, cobalt, mercury, cyanide, 

sulfur dioxide and xanthates. A report by the Industrial Disease Standards Panel (IDSP, 1994) assessed 

lung cancer in hard rock mining and 

the potentially harmful agents included ionizing radiation, arsenic, 

nickel, sulfuric acid mist, asbestos, 

diesel emissions, oil mist, blasting 

agents and silica. 

The wide range of chemicals 

used in mining lead to a variety of 

potential exposure hazards. Chemicals posing a physical or health hazard can enter the body 

via the following three main pathways (Patnaik, 1999): 

• 	Contact with the eyes and skin: When chemicals come 

in contact with the skin they can cause dermatitis, 

rashes or burns. Alkalis, acids, soaps, detergents and 

organic compounds are the most frequent causes of 

dermatitis and the response to the exposure can be 

exacerbated by humidity, friction and excessive heat. 

Poisonous chemicals, as well as their vapors, can also 

cross the skin barrier and enter the blood stream 

(Patnaik, 1999). If a chemical gets into the eye it can 

burn, cause an infection or hinder vision. Chemical 

eye burns typically occur from alkalis, acids or organic 

solvents (Weeks et al., 1991). 

• 	Ingestion: Exposure due to ingestion of a chemical 

can occur if hands are not thoroughly cleaned after 

handling chemicals. Exposure occurs from subsequent 

handling of food, utensils, cigarettes or other items 

that might be placed in the mouth. 

• 	Inhalation: Inhaled chemicals can cause acute responses such as nausea, headaches, shortness of breath 

and asphyxiation, or they can have chronic outcomes 

such as central nervous system disorders and respiratory illnesses. 

A study by the National Institute for Occupational 

Safety and Health (NIOSH) summarized a survey that 

focused on injuries, illnesses and hazardous exposures to 

mine workers (NIOSH, 2000). This survey included an 

analysis of MSHA data for the 10-year period from 1986 
 

through 1995, to determine the number and nature of 

nonfatal injuries within each commodity. Nonfatal chemical burns and poisonings, listed by type of operator are 

presented in Table 1. 

 

Table 1 

Total number of nonfatal injury cases and those caused 

by chemical burns and poisonings for 1986 through 

1995 (NIOSH, 2000). 

All Chemical 

Operators nonfatal burns Poisonings 

Coal 131,144 701 244


 Metal 31,494 733 166


 Nonmetal 17,133 239 103


 Stone 54,359 1,132 217
 

Sand and gravel 19,406 127 141


 Totals 253,536 2,932 871
 

Most of the burn cases resulted from 

exposure to acids and alkalis, with the eye as the most 

common site of injury. The majority of the poisonings 

were from noxious mine gases. The injuries typically occurred in the summer months and workers with less than 

fi ve years of experience had more burns and poisonings 

than whose who had more experience. 

A study of all chemical-related injury and illness 

cases from 1983 though 2000 was completed by MSHA 

researchers (MSHA, 2002). That study identifi ed 4,652 

chemical burn cases, 805 poisonings and 635 cases of 

dermatitis. 

The results of these studies, along with concerns for 

the many workers who are regularly exposed to a variety of chemicals, prompted MSHA to develop the Hazard Communication (HazCom) standard. The standard 

was designed to increase worker awareness about the 

use of PPE and, ultimately, to reduce injuries, illnesses 

and deaths due to overexposure or misuse of chemicals. 

Learning about the dangers of working with chemicals 

increases the understanding of the importance of using 

PPE. In addition, implementation of the information provided on MSDSs regarding the chemical properties and 

health hazards is important in prevention of overexposure or misuse of chemicals. 

The HazCom rule became effective in 2003. Chemicals at a mine would be considered hazardous for the 

purpose of the rule if the chemical has the potential to 

harm persons as indicated by any of the following: 

• the chemical’s label or MSDS indicates that it is a 

hazard, 

• the chemical is produced at this location and available 

evidence concerning its physical or health hazards 

indicates that it can be a hazard to exposed persons, 

or 

• the chemical is a mixture produced at this location 

which contains at least 1% of a hazardous chemical 

or 0.1% of a carcinogen. 

If the answer was yes to any of these questions, and 

it was not exempted in the MSHA rule, 30 CFR, Part 

47, it would need to be on the mine’s hazardous chemical list. 

To quantify the number of chemicals currently in use, 

NIOSH queried several hard-rock mining companies in 

2008.These mines volunteered to share their chemical inventories, resulting in a list of more than 1,000 chemicals 

that are currently in use. 

This paper summarizes a recent review of the MSHA 

illness and injury database, which was conducted with 

two goals. The primary goal was to determine if miners 

are at risk from exposures to chemicals used in the mining industry, determine the nature and sources of the 

illnesses and injuries, and communicate that information 

to the mining industry. The second goal was to investigate trends in the data that might target opportunities 

for health and safety research that would help prevent 

chemical-related injuries and illnesses. 

Methods 

MSHA’s definition of an injury is “any injury to a 

worker that occurs at a mine for which medical treatment is administered or that results in loss of consciousness, inability to perform any job duties on any day after 

an injury, or transfer to another job” (U.S. Department 

of Labor, 2007b). An illness is defined as “an illness or 

disease of a worker that may have resulted from work at 

a mine or for which an award of compensation is made” 

(U.S. Department of Labor, 2007b). 

When illness or injury occurs in the mining workplace, 

mine operators and contractors must file a Mine Accident, 

Injury, and Illness Report (MSHA Form 7000-1) within 

10 days of the accident, injury or diagnosed illness (injuries requiring only firstaid are not considered reportable). 

The report includes demographic information such as 

age, sex, total years of mining experience and information 

regarding the incident, such as the body part impacted, 

the incident location, the source and nature of the injury, 

a brief narrative detailing how the incident occurred and/ 

or other pertinent information. This information is then 

entered into the MSHA database (U.S. Department of 

Labor, 2007a). In the current study, data from the MSHA 

database for the years 1999-2006 were analyzed.The data 

were imported into a Microsoft Excel1

1 Reference to a company name or product does not 

imply endorsement by NIOSH. 

database, and each 

case was verified by reading the accompanying narrative 

(MSHA Form 7000-1). 

Injury or illness cases were classifi ed as chemical-related if the worker inhaled, ingested or came into direct 

contact (through eyes or skin) with a chemical. Cases 

that could not be verified were removed from the data 

set. Cases were reviewed to capture only those that were 

chemical-related based on the nature and source of the 

injury (office workers excluded because they have minimal contact with hazardous chemicals).To be considered 

in this review, cases had to meet the following criteria: 

• the source of the injury was listed as acids/alkalis, 

chemicals/chemical compounds, noxious mine gases 

or oxygen defi cient atmosphere; 

• 	the nature of injury was listed as a chemical burn, poisoning systemic, dermatitis, occupational diseases, black 

lung, disease/contagious infection, other pneumoconiosis, asbestosis, silicosis and anthracosis; and/or 

• the case contains reference to chemicals including, 

but not limited to, acids, alkalis and caustic solutions, 

asbestos, asphyxiates, coal dust, crystalline silica,
 

cyanide, carbon monoxide, heavy metals, metal dusts, 

mine gases (e.g., sulfur dioxide, oxides of nitrogen or 

methane), reagents, respiratory irritants, solvents and 

xanthates. 

After identifying the injury and illness cases that were 

chemical-related, the data were further organized using the groupings in the MSHA database. The groupings included: mine type, part of body affected, standard 

industrial code, job title, state, source of injury or illness, 

accident/injury/illness classification, injury type, degree 

of injury/illness, mine worker’s activity at the time of the 

injury or illness, the nature of the injury or illness and the 

narrative describing the injury or illness. 

Incidence rates (number of new cases reported each 

year per 100 workers) were calculated for each year using the identified cases of chemical-related injury and 

illness. The number of reported cases was divided by the 

total number of hours worked and multiplied by 200,000 

(MSHA standard-assumes a 40 hour work week, 50 

weeks per year for 100 employees). This calculation was 

done because MSHA records the hours worked and not 

the number of employees for each mine. For this review, 

work hour information was gathered from the Mine, Injury and Worktime, Quarterlies Closeout Editions for 1999 

through 2006 (U.S. Department of Labor, 1999-2006). 

Results 

The purpose of this review was to determine if miners were at risk from exposures to chemicals used in the 

mining industry, determine the source (cause) and nature 

(effect) of the illnesses and injuries, and to communicate 

that information to the mining industry. 

Injury rates and severity. Based on the sorting criteria 

for this review, there were 2,705 cases of chemical-related 

injuries and illnesses reported from 1999 through 2006 

(Table 2). 

Table 2 

Combined number of chemical-related injuries and 


illnesses for the years 1999 through 2006.
 

 Year Number Year Number 

1999 

 2000 

 2001 

 2002 

394 

382 

344 

388 

2003 

2004 

2005 

2006 

317

279

322

279 

 Total: 2,705

The results for the calculation of nonfatal days lost 

(NFDL), no days lost (NDL) and occupational illness 

incidence rates during the review period are shown in 

Figs. 1, 2 and 3, respectively. 

FIGURE 1 

Incidence rates by year for NFDL (n = 887). 

FIGURE 2 

Incidence rates by year for NDL (n = 893). 

FIGURE 3 

Incidence rates by year for occupational illnesses (n = 

925). 

Source and nature of illness and injury. According 

to the analysis of the injury and illness case narratives 

recorded in the MSHA database, a total of 66 chemicals 

were responsible for the 2,705 cases.The sources of chemical-related injuries and illnesses are shown in Fig. 4. Acids and alkalis, defined by MSHA to include wet cement, 

wet grout, shotcrete, lime-cement dust, trona and rock 

dust, accounted for about 39% of all cases. Pulverized
 

minerals are defined by MSHA to include fi nes, particles 

and mine dust, and these accounted for about 28%. 

FIGURE 4 

Source of chemical-related injuries and illnesses, 1999­

2006 (n = 2,705). 

Chemicals accounted for about 13%, and coal/petroleum products, including processed coal, clinkers, methane gas and solvents, creosote, hot oil, hydraulic fl uid, 

antifreeze, gasoline and mouse milk accounted for about 

8%. These four sources accounted for about 94% of all 

chemical-related illnesses and injuries. 

The nature of chemical-related injuries and illnesses 

is shown in Fig. 5. Chemical burns accounted for about 

57% of all cases, followed by coal workers pneumoconiosis (CWP) (24%), poisonings (8%), dermatitis (3%) 

and silicosis (2%). 

FIGURE 5 

Nature of chemical-related injuries and illnesses, 1999­

2006 (n = 2,705). 

The main route of chemical exposure was through direct contact (64%), and less than 

1% of the cases involved ingestion of a chemical. The 

most common affected sites were the eyes and chest 

(lungs), 37% and 29%, respectively, while injuries that 

affected more than one body part accounted for 7% of 

the cases. 

Job classifi cations. The number of cases varied by job 

or profession.The five job classifications with the highest 

number of injuries and illnesses were: 

• cleaning plant operator/media operator/boney preparation plant operator/crusher worker (18%), 

• mechanic/repairman (16%), 

• laborer/utility man/pumper (12%), 

• laborer/muck machine operator/pipe gin (6%) and 

• electrician (3%). 

This constitutes about 1,490 cases (55%). Those jobs 

(276 different job types) with fewer than 50 cases were 

grouped together and accounted for the remaining 45% 

of the cases. 

For the job classifi cation with the highest number of 

cases (cleaning plant operator/media operator/boney 

preparation plant operator/crusher workers), the activities being performed when the injuries or illnesses occurred were: 

• handling supplies or material (loading or unloading) 

(24%), 

• maintaining and repairing machines (21%), 

• working around mill equipment (11%) and 

• working with chemicals (9%). 

Eighty-two percent of these cases resulted in a chemical burn with acids and alkalis as the most common source 

of injury followed by chemicals/chemical compounds. 

These injuries typically occurred in mines or processing plants where the primary commodities mined were 

lime/limestone (25%), cement (23%) and alumina (19%). 

Other significant job-related data included: 

• approximately 40% of cases among mechanic repairmen occurred during machine maintenance; 

• common activities among the laborer/utility man/ 

pumper included handling supplies or materials 

(24%), machine maintenance and repair (20%) and 

working with chemicals (8%); and 

• the most frequent source of injury for electricians was 

pulverized minerals (47%), followed by acids/alkalis 

(30%). 

Discussion 

Based on results from this review, 2,705 miners suffered either an injury or illness caused by chemical exposure during the period 1999 through 2006. While the 

MSHA illness and injury database is not the only source 

of information regarding chemical-related miner injuries 

and illnesses, it is a unique and valuable tool for analyzing 

the types of cases. Analysis of the case narratives along 

with the quantitative data presented led to the following 

summations regarding incidence rates, the sources and 

nature of illnesses and injuries and job types as they relate to exposure to chemicals. 
 

Injury rates and severity. About 2% of all injuries 

and illnesses reported to MSHA from 1999 through 2006 

were chemical-related. While this percentage is small, it 

translates to an average of 338 cases yearly. Of the 2,705 

cases, 66% resulted in injuries and 34% resulted in illnesses. A slight increase for both NFDL and NDL and 

a decrease in occupational illnesses was apparent. The 

correlation between year and incidence rates for NFDL 

is 0.2 (p > 0.35) and for NDL is 0.1 (p > 0.45), indicating 

no statistically signifi cant correlation. However, the correlation between year and illness incidence rate is 0.8 (p 

< 0.003), which shows a strong correlation (decline from 

1999 to 2006). 

The significance of injuries to the mining industry 

translates into employee distress and pain and suffering 

for the workers and their families. The mining industry 

also suffers from lost resources and economic loss. For 

example, Camm and Girard-Dwyer (2005) estimated the 

cost of one nonfatal injury at a sand and gravel mine to 

be $46,400 in 1990; when accounting for inflation, in 2008 

dollars this cost is $77,650. 

Source and nature of illness and injury. The 2,705 cases 

of illnesses and injuries were associated with 66 different 

chemicals. However, about 67% of all the identifi ed cases 

were a result of pulverized minerals (specifically coal 

dust) and acids/alkalis (specifically lime and cement). 

Coal dust is the single leading cause of illness among 

miners and is responsible for CWP, which results from 

inhalation of coal dust and continues to be a signifi cant 

problem in the mining sector. Because CWP has a latency period of 20 to 30 years, it is diffi cult to determine 

if or when the number of cases will begin to signifi cantly 

decrease. In addition, a resurgence of CWP in certain 

geographical areas may present a new health and safety 

research challenge (Dos et al., 2005). Coal dust is the 

leading chemical contributing to chemical-related illnesses and researchers need to continue to develop new 

methods (e.g. NIOSH Personal Dust Monitor) to protect 

coal workers from inhalation of coal dust (Volkwein et 

al., 2004). 

Acids and alkalis (specifically lime and cement) were 

the source of about 39% of the total cases. Combined, 

injuries and illnesses from exposures to lime and cement 

totaled more than coal dust. MSHA narrative data verify 

that most lime and cement cases are from direct exposure to the skin, resulting in chemical burns. For example, 

selected narratives mention that workers wait until the 

end of their shift to remove clothing and footwear after 

significant exposure to lime. This allows the lime to be in 

contact with the skin for longer periods of time and often 

results in severe chemical burns.Wearing the proper PPE, 

including protective eyewear, gloves and hats, is essential 

to prevent burns from lime contact. Immediately removing the contaminated clothing decreases the likelihood of 

a chemical burn occurring. 

The most common body part affected were the eyes. 

Nearly 37% (988) of the cases resulted in injuries to the 

eyes. As liquid chemicals are transferred from container 

to container or used for certain applications, splashing 

can occur.An average of 125 “chemical-to-the-eye” injuries occurred each year from 1999 through 2006. Narrative data did not indicate if protective eyewear was worn 

when the injuries occurred. 

Job classifi cations. The job with the highest number of 

injury and illness cases was cleaning plant operator/media operator/boney preparation plant operator/crusher 

worker. This particular job is actually a compilation of 

several jobs. Cleaning plant operators are responsible 

for maintenance of plants, media operators are responsible for handling reagents (light oils), boney preparation 

plant operators oversee removal of “bone” from coal, and 

crusher workers use large crushers to break mined material. Many of the identified cases involved both inhalation 

and direct contact during handling of chemicals. Some of 

the cases result in CWP from workers inhaling coal dust 

generated during handling and/or crushing operations, 

illuminating the need for proper PPE when working with 

coal dust. 

Jobs that involve handling lime/cement also present 

high risk for workers. It is apparent from the case narratives that there are many job types that have potential for 

exposure to these materials. It is important to address the 

resulting burn cases through mitigation of the sources of 

exposure rather than looking at the problem from a job 

classifi cation perspective. 

Because the MSHA database lists a total of 281 different job classifications, there are many jobs for which 

relatively few illnesses and injuries are associated. This 

makes it difficult to explain worker risk from job descriptions alone and highlights the importance of examining the sources and nature of injuries more closely, 

as they often are more indicative of risk than job type 

alone.Another drawback of looking at only the job classification is that injured workers may not have been 

engaged in work that falls within their job description. 

For example, a roof bolter may have suffered a chemical-related injury or illness while performing an activity 

other than roof bolting. Therefore, the job classifi cation 

may not be a reliable factor for determining a chemicalrelated case. 

Summary 

From 1999 through 2006, a total of 2,705 chemicalrelated injury or illness cases were reported to MSHA. 

For these years, the incidence rate for chemical-related 

injuries did not change significantly; however, the incidence rate for chemical-related illnesses showed a 

significant decline. Coal workers pneumoconiosis was 

the single most common illness listed, while chemical 

burns were the most common type of injury. The burn 

cases are mainly associated with materials containing 

lime and cement and the most common injury was to 

the eyes. 

Based on this review, the mining industry should 

focus on prevention of chemical-related injuries and 

illnesses resulting from exposure to acids/alkalis including wet cement or grout, shotcrete, lime, trona and 

rock dust. Chemical burns accounted for many injuries 

and illnesses; therefore, safety management personnel 

in mining companies need to carefully examine their 

PPE requirements, training methods and safety culture 

to insure that their workers are protected. To decrease 

the number of burn injuries, a thorough investigation is 

needed to determine what factors (e.g., lack of safety 

training, lack of proper safety equipment or repetitious 

tasks that can lead to shortcuts) are responsible for 

these cases. 
 

Acknowledgments 

The authors thank Laura Martini, NIOSH Spokane 

Research Laboratory, for providing expertise in extracting and formatting the MSHA data. 

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