NIOSH Research Rounds

NIOSH Research Rounds is a monthly bulletin of selected research conducted by researchers at NIOSH and NIOSH-funded researchers at other institutions.
Volume 4, Number 7 (January 2019)

Inside NIOSH:
Risk of Mining-related Lung Disease Varies by Region, Mine Type, and Safety Observance

With the recent resurgence of the most severe form of black lung disease among coal miners, especially in central Appalachia, understanding and preventing exposure to the respirable, or inhalable, dust generated during the extraction of coal is paramount.  Black lung is a form of pneumoconiosis, or scarring lung disease, caused by breathing in dust that can occur with exposure to respirable coal mine dust.

Understanding workplace factors that contribute to lung disease is complicated because symptoms of dust-induced lung disease often take years to become apparent. But in a first of its kind study, NIOSH investigators have taken a unique approach by looking at nearly two decades of information about compliance with health and safety regulations leading up to lung disease diagnoses among miners.

Mining companies are required by law to report work-related injuries and illnesses to the U.S. Department of Labor’s Mine Safety and Health Administration (MSHA), the enforcement agency for mining safety and health regulations. Additionally, MSHA keeps records on the enforcement of health and safety regulations in U.S. mines. Using publicly available information contained in MSHA’s injury and illness, enforcement, and employment databases, the investigators evaluated the relationship between compliance with federal health and safety regulations and lung disease diagnoses. This work provided a glimpse into the working environment, including health and safety practices, before mines reported a diagnosis of lung disease within their workforce.

The investigators looked at individual reports of lung disease in the MSHA injury and illness database between 2006 and 2015. From 8,165 mines, they found 730 reports, of which 662 were black lung reported from coal mines. By region, Appalachian mines accounted for the most, with 640 diagnoses. In contrast, 22 cases were reported in the western, southern, and north central regions combined, meaning that Appalachian miners were approximately 9 times more likely than miners from other regions to report lung disease, according to MSHA’s injury and illness database. Similarly, underground miners were approximately 3 times more likely than surface miners to report a diagnosis of lung disease.

Next, the investigators looked at the effects of safety and health enforcement from 1996-2005 on later cases of lung disease from 2006-2015. Focusing on regulations governing management practices and engineering controls, or tools, to control dust, they found that mines that did a better job of complying with these regulations were less likely to report cases of lung disease. The study’s findings underscore the importance of continued dust monitoring and consistent control techniques to prevent exposure among miners.

In addition to studying these critical areas, NIOSH administers the Coal Workers’ Health Surveillance Program, a federally mandated screening and surveillance program which provides chest X-rays and lung-function testing at no cost to eligible miners nationwide.

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NIOSH Research Rounds is Brought to You By:
  • John Howard, M.D., Director
  • Christina Spring, Editor in Chief
  • Anne Blank, Managing Editor
  • Donjanea Williams, Contributing Editor
  • Sarah Mitchell, Contributing Editor
  • Jeanette Novakovic, Copy Editor
  • Glenn Doyle, Technical Lead
  • Tonya White, Technical Support

Chemical Exposure in Healthcare Differs by Task and Product

Cleaning and disinfecting products are complex mixtures of chemicals that can irritate the skin. Evidence also shows that exposure to these products may increase the risk of work-related asthma among healthcare workers. But the effects of specific chemicals remain unclear. Now, a NIOSH study published in the journal Annals of Work Exposures and Healthexternal icon has added to our understanding by linking products and tasks to specific exposures.

In work-related asthma, symptoms such as wheezing, coughing, chest tightness, and shortness of breath occur from exposure to substances found in the workplace. To identify these exposures in a healthcare setting, investigators measured air levels of 14 chemicals commonly present in cleaners and disinfectants. Known as volatile organic compounds, or VOCs, these chemicals evaporate at room temperature, becoming airborne, and may potentially cause or worsen asthma if breathed in.

First, the investigators took 143 pairs of air samples. Each pair included one sample from study participants’ personal breathing zone and one from areas where they performed various cleaning and disinfecting tasks. They then used statistical methods to group the workers by cleaning task and products used into eight clusters across different occupations and departments.

Results showed that healthcare workers faced exposure to numerous chemicals, and that exposure to specific chemicals varied by task and product. For example, exposure to two chemicals (chloroform and α-pinene) occurred at higher levels during patient and other cleaning tasks when healthcare workers used products that contained chlorine. Exposure to two other chemicals (d-limonene and 2-propanol) was significantly higher during tasks that involved sterilizing and disinfecting medical instruments. One task—surface and floor cleaning, and floor stripping—exposed workers, employed primarily as housekeepers and floor strippers or waxers, to as many as five different measured air-borne chemicals. Based on the ingredients of cleaning and disinfecting products, healthcare workers are potentially exposed to many more chemicals than the ones measured in this study.

The study also found differences in exposure by occupation. Nursing assistants, clinical laboratory technicians and licensed practical nurses had higher personal exposures to more than half of the chemicals measured compared to other occupations. Some exposures were specific to occupations, for example, dental assistants had the highest levels of methyl-methacrylate exposure among all occupations.

Study participants comprised 100 healthcare workers at four U.S. Veterans Affairs hospitals and teaching hospitals. They represented 14 occupations: clinical laboratory technician, nursing assistant, dental assistant, dental laboratory technician, endoscopy technician, floor stripper or waxer, housekeeper, licensed practical nurse, medical appliance technician, medical equipment preparer, pharmacist or pharmacy technician, registered nurse, respiratory therapist, and surgical technologist.

The study’s findings underscore the need for additional research on specific cleaning and disinfecting products in different settings and tasks within a hospital. Next, the investigators plan to use these findings to link actual symptoms of work-related asthma to specific exposures, tasks and cleaning and disinfecting products.

More information is available:


Outside NIOSH:
Gas-burning Fryers Source of Carbon Monoxide Leak at Industrial Kitchen

An uncommon source of carbon monoxide poisoning—industrial gas-burning fryers—caused carbon monoxide poisoning among a large group of workers at an industrial kitchen, according to an investigation published in the CDC’s Morbidity and Mortality Weekly Report (MMWR).

Carbon monoxide is a colorless, odorless, and potentially deadly gas. When carbon monoxide is inhaled, a substance called carboxyhemoglobin forms in the blood. This substance prevents the blood from carrying oxygen to tissues and vital organs in the body. Annually, carbon monoxide poisoning kills approximately 400 people in the United States.

In September 2017, 40 workers from an industrial kitchen presented to several Wisconsin hospitals for treatment after a suspected carbon monoxide leak led to a workplace evacuation. Emergency room staff in two of the hospitals consulted the Wisconsin Poison Center for guidance on evaluation and treatment of these patients. The center alerted the NIOSH-funded Wisconsin Division of Public Health, Occupational Health Surveillance Program, which launched an investigation that included interviewing emergency responders and reviewing workers’ medical records.

Carbon monoxide poisoning is defined as carboxyhemoglobin blood levels of more than 5% for nonsmokers and more than 10% for smokers or those whose smoking status is unknown. Most of the patients had carboxyhemoglobin blood levels higher than the cutoff for carbon monoxide poisoning—in some cases, more than twice as high. The most common symptoms included headaches (93%), dizziness (40%), and nausea (38%). There were no deaths.

In the facility, carbon monoxide levels were as high as 313 ppm (parts per million) near the gas-burning fryers, which is well above the NIOSH recommended exposure limit of 200 ppm.  Gas burners were the carbon monoxide source. The carbon monoxide gas built up in the plant due to inadequate ventilation, according to the Occupational Safety and Health Administration, which also investigated. Although gas-burning appliances are not a common cause of work-related deaths due to carbon monoxide poisoning, it is important to maintain and ventilate them properly, and install carbon monoxide detectors to prevent exposure among workers.

More information is available:


Investigation Shows Limited Respirator Use Among Emergency Responders after Toxic Gas Exposure

Most of the emergency responders dispatched to a serious incident involving a toxic gas exposure did not use required respirators for breathing protection, according to a NIOSH-funded investigation published in the CDC’s Morbidity and Mortality Weekly Report (MMWR).

The gas, phosphine, forms when pesticides containing aluminum phosphide mix with water. These pesticides are restricted to certified users because short-term exposure can cause respiratory and cardiovascular, or heart and blood vessel, complications, and can be fatal. Federal regulations require emergency crews on the scene with such hazardous substances wear personal protective equipment, including a respirator. Multiple studies, however, show this does not typically happen. Little information is currently available on how to increase emergency responders’ compliance.

The NIOSH-funded Texas Department of State Health Services reviewed this case of phosphine exposure among 51 hazardous materials emergency responders who evacuated and treated residents at an Amarillo, Texas, home after an outdoor pesticide application. The scientists reviewed call records from the Texas Poison Control Network related to the exposure and the results of a standardized health questionnaire completed by the emergency responders afterwards. The questionnaire included information about the responders’ role in the incident, respirator use, previous response training, and possible exposure to phosphine and associated health effects.

More than 78% (40) of the emergency responders did not wear a respirator during the response. Of these, 15 received medical treatment and seven reported new or worse phosphine exposure symptoms within a day after the incident. Their symptoms included eye pain, headaches, dizziness, abdominal cramps, and nausea.

The majority of the 51 emergency responders reported being trained in emergency response and understood standard operating procedures within their agency for handling incidents with hazardous substances. They gave several reasons for not wearing a respirator: being unaware that it was necessary (five), focusing on rescuing people (four), being unaware of the chemical’s presence (four),  feeling it was not required for their task (two), and lacking equipment (one).

These findings show that emergency responder trainings alone do not result in proper use of respirators during incidences with unknown hazardous substances. Few studies exist of behavioral interventions related to the use of respirators and other personal protective equipment among emergency responders.  Also, methods for improving compliance with existing guidance and regulations are not well understood. More research is needed to evaluate effective interventions to help ensure that emergency responders comply with current recommendations and regulations for personal protective equipment, according to the scientists.

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Page last reviewed: January 16, 2019