Workplace Safety | Stats + Stories Episode 10 / by Stats Stories

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Chris Whittaker Sofge is a toxicologist who leads a team that conducts quantitative risk assessment for hazards in the workplace. She is the Chief of the Risk Evaluation Branch in the Education and Information Division at the National Institute for Occupational Safety and Health Her group conducts quantitative risk assessment for hazards in the workplace. To learn more about NIOSH work, check out worker safety and health research data from A (Adult Blood Lead Epidemiology and Surveillance) to (almost) Z (Young Worker Safety and Health) ).

+ Full Transcript

Bob Long: We've all seen pictures of workers dressed in special gear because they're dealing with the hazardous nature of their jobs. Workplace safety has become an important issue in America...and you might be surprised at some of the occupations where people face chemical exposure. Take for example workers at a microwave popcorn industry plant who developed a form of lung disease. Hi. I'm Bob Long, and welcome to Stats and Stories... a program where we look at the statistics behind the stories, and the stories behind the statistics, and our focus today is on workplace safety issues. Joining me on Stats and Stories are our regular panelists - Miami University Statistics Department Chair John Bailer and Media, Journalism and Film Department Chair Richard Campbell. Before we talk to our special guest about workplace hazards, Stats and Stories reporter Bethany Miller talked with one scientist who's involved in studies of workplace hazards.

Bethany Miller: The workplace can be hazardous for some employees --- risk of exposure to cancer-causing chemicals or other safety-related issues. Federal agencies like the National Institutes for Occupational Safety and Health - try to identify potential workplace hazards and help to craft rules to safeguard workers. Leslie Stayner spent 23 years at NIOSH - doing studies to identify potential hazards and determine how much risk is involved. Regulators at the Occupational Safety and Health Administration rely on scientists to tell them the risks that certain chemicals pose. Stayner says these studies help determine how federal rules could safeguard workers.

Leslie Stayner: We're involved in a number of important issues. We're involved in OSHA standards, testimony for cadmium, silica; we did extensive work on coal dust, and noise and hearing loss and a large number of other issues.

Miller: For example, Stayner was involved in studies of workers exposed to cadmium, and found the risks were unacceptably high…

Stayner: The workers we studied and did our risk assessment on were workers that worked with cadmium that had been refined. But the results of our risk assessment were generalized to all workers who were exposed to cadmium.

Miller: Stayner says sometimes studies of workplace risks extend beyond America's borders. He points to work he was involved with regarding the dangers of formaldehyde...

Stayner: The research that I did on formaldehyde, along with others at NIOSH and others at NCI, were highly influential in the determination by the international agency for research on cancer that formaldehyde is a known human carcinogen. And that has very wide implications - not only for regulation here in the United States, but worldwide.

Miller: Leslie Stayner says assessing risks in the workplace is no easy task. It could take 3 to 5 years to determine if a chemical causes cancer and another year to assess what level of exposure is considered unsafe. Stayner says developing federal rules can take much longer.

Stayner: The burden of OSHA and the EPA to set regulations - they have to go through all kinds of reviews within the government and also with external forces, so these regulatory processes can drag on for years.

Miller: Leslie Stayner now does research at the University of Illinois at Chicago on issues involving water contamination. For Stats and Stories, I'm Bethany Miller.

Long: Our special guest today is Chris Whittaker Sofge. She's the Chief of the Risk Evaluation Branch at NIOSH - which is the National Institute for Occupational Safety and Health. Chris has worked at NIOSH for a decade - and she leads a team that conducts risk assessments for workplace hazards such as chemical exposure.

Chris Sofge: I'm happy to be here today and talk about what is going on at NIOSH. We look at chemical exposures in the workplace by looking at both studies of workers in the workplace, epidemiological studies, and also we look at animal studies of toxic substances, and then we use that data to extrapolate to what exposures would be safe or safer for workers that are exposed to different kinds of chemicals in the workplace.

John Bailer: So how do you use some of the data that you've collected there, to try to establish some of these exposure levels?

Sofge: Well we used to do a very simple analysis and look for what levels didn't show an elevated health effect; for example, if we're looking for cancer in an animal study, we'd look for the dose that didn't produce any cancer in the animals and then we would use uncertainty factors or safety factors to predict what would be safe for humans. Nowadays we'd get a little bit more sophisticated and do some statistical modeling to use all of the data that's in an animal study to predict what levels are safe for human exposure, especially workers.

Bailer: So, you know I love to hear words like "statistical modeling" in describing the sort of work, even though it makes some of my colleagues uncomfortable here at the table. When you think about some of these models, what kind of models do you mean? What does that mean in this context?

Sofge: Well it's looking at the exposure response data, so we're looking at how much or what concentrations of a chemical in an environment will produce a health effect, in the animals in this case, so we look at that at different doses. So if we have low-doses, medium-doses, and high-doses, how does the number of health effects we observe change over that range, and we can use that to then basically draw a picture of what the exposure and response looks like at low levels and that's hopefully where the workers are exposed, at low levels.

Long: I'm kind of curious because I know you're dealing pretty much with the research that goes into all of this, but then there have to be other agencies, I'm sure, that are involved in actually implementing the guidelines, I wanted to maybe have you explain how that whole process works, once you've done that background research.

Sofge: We do the research and we actually produce recommendations and those come out in the form of recommended exposure limits, and then other agencies look at it and make regulations. For worker health, that would be OSHA, or the Occupational Safety and Health Administration, and I used to work for OSHA as well, early in my career. And what they do, they develop regulations about how much an employer has to keep, what levels the exposure has to be kept at to keep workers healthy.

Long: I'm just kind of curious too, how long, a lot of times from the time you first find out about something to the time a regulation is actually implemented, we're talking several years, aren't we, a lot of time before that actually takes place.

Sofge: Yeah, it can be many years because like for the example that you used in the opening statement which is popcorn manufacturing, so this is a food production plant and people don't think of chemical exposures in the food, and actually the chemical that is responsible for the lung disease that was found in workers is called diacetyl. That is actually butter flavor, and it's the natural butter flavor that we find in our sticks of butter in our refrigerator at home, but when you concentrate it to put it into bags of microwave popcorn, they're heating it up and workers are inhaling it and it's at a much higher concentration than you would have from frying up some butter at home. So that concentrated of an exposure would lead to health effects and decreased lung function and actually a very horrible lung disease in workers.

Long: John Bailer, over to you next.

Bailer: A quick follow-up on that, how did the idea of this example, diacetyl, how did that come to the attention for any kind of action?

Sofge: Well actually back in 1984 was the first documented case, the disease is horrible, it's called bronchiolitis obliterans. It sounds basically as horrible as it is and the only treatment for it once you have it is a lung transplant, so it's a very serious disease; people have died from this. So back in 1984, an occupational physician found a couple of cases of this in a microwave popcorn plant, but they didn't know what was causing it, they didn't know what was going on with the workers there. So then, in the late '90s, more cases of bronchiolitis obliterans started popping up and occupational physicians started to notice this and in 2000 NIOSH actually did some health hazard evaluations where they went out to the worksites of several microwave popcorn plants and they evaluated the workers, they measured their lung function, and they measured the exposures of different chemicals because at that time they didn't know what it was related to and eventually they found the relationship between diacetyl exposure and this disease, or decreased lung function.

Long: You're listening to Stats and Stories and we're discussing the statistics behind the stories and the stories behind the statistics, just like the example we gave you there. And we're focusing this time on the importance of dealing with chemical exposure in the workplace. I'm Bob Long along with me, our regular panelists Miami University statistics department chair John Bailer, media, journalism, and film chair Richard Campbell, and again our special guest Chris Whittaker Sofge of the National Institute for Occupational Safety and Health. I want to go to Richard Campbell for the next question.

Richard Campbell: Chris, one of the things that we are interested in on this show is the way that scientific research and stories about data research gets translated to the public and a lot of time the role, a key role in that process is the role of the journalists explaining things that are, as Bob has pointed out already, are complicated. One of my favorite quotes is from the author David Halberstam who says that "The journalist's job is to make complicated interesting." So sometimes in doing that, things get simplified, so I guess the question for you is could the media, the news media do a better job explaining what it is you do? Maybe you could give us some examples.

Sofge: Well that's a good question. I think it does get very complicated when you're doing risk assessment because we're talking about statistical models and chemicals with long, complicated names, and we need a way to make it simpler because basically what we're trying to do, when people ask me what I really do, I say that our job is to say that's not safe, don't breathe that. It gets a little bit more complicated because we're trying to tell people how much not to breathe, or how much an employer needs to keep the levels at to make it safe. So I think understanding the chemistry behind things, or understanding the statistics would be helpful, but being able to explain kind of what the goal is, and that is to protect workers, I think that would be helpful.

Long: One of the things we always like to do too, is find out what people on the street know about our particular subject, so one of the things we asked them for today was, what kind of workers do you think face chemical exposure in the workplace?

Woman on the street #1: I think people who work outside a lot, so like construction workers. Maybe people who do a lot of landscaping with fertilizers, and also maybe people in the medical field, who have to deal with a lot of chemicals and medications and things like that.

Man on the street #1: Any type of construction worker, people that paint contractors, kind of like contractors, things like that. They're just around different like dust particles that can be dangerous. Painters obviously with the fumes from the paint.

Woman on the street #2: Science or like researching. You are exposed to a lot of different hazardous materials. Areas like chemists, scientists and things like that.

Woman on the street #3: People who work at a garbage disposal place because they have to use a lot of chemicals to keep the smell down.

Woman on the street #4: Probably anyone in the medical profession or like custodial workers dealing with cleaning up messes. There are strong chemicals there, or anyone working in like agriculture.

Long: Chris, maybe we'll have you address that issue too because I imagine there's a wide range of types of cases like Richard brought up, things where, and John also, examples of types of things, so maybe if you could give us an idea of the range of kinds of things that NIOSH has investigated over the years, the types of jobs.

Sofge: Yeah, for chemical exposures we've had all sorts of kinds of occupations that on the face of it you don't think of as chemical exposures. The example I used earlier with the popcorn worker, that's the food preparation. Well diacetyl is also found in all sorts of food preparation including candy making and coffee grinding, all sorts of things. Diacetyl is a very nice flavoring and it goes in a lot of products so there's lots of chemical exposure in food manufacturing that we don't think of as chemical exposures. There's also hospital workers who are exposed to tons of different chemicals and anybody who is involved in cleaning, all sorts of cleaning products are chemical exposures and office workers can be exposed to things like printer toner and things like that. All sorts of jobs have different kinds of chemical exposures, and then there's, of course if you're working in a chemical plant or manufacturing where you're looking at metalworking fluids or something like that, almost every job has some sort of chemical exposures with the exception of probably college professors.

Long: With that, we'll go to a college professor, John Bailer, for the next question.

Bailer: Yeah, our exposures tend to be to other things, like stress. So there are other exposures that you worry about. So you've given us a number of examples that relate to chemicals in the workplace and diversity of different types of workplaces that have chemical exposure, but can you talk about some of the other populations, and perhaps some of the other types of exposures that are non-chemical that could be thought of as hazards in the workplace?

Sofge: The other kinds of work that we do, we try to prevent, as NIOSH, we try to prevent worker injuries and illness of all types, so that can be either falling off of a roof or stress in college professors or it could be, so we look at firefighters, we look at jockeys or football players or waitresses or hair dressers. We had a really interesting example not too long ago about how some hairdressers were exposed to formaldehyde in the salon and things that people don't think of as real chemical exposures; they're everywhere.

Campbell: One of the things that I'm interested in is some of those things that you were just talking about, what kind of outreach do you do to ensure the public and these worker groups know what's going on, and how much push-back is there when they feel like they haven't had this explained to them fully? I can imagine there are some workers that say, "That's silly, I feel fine." And again, I think the role of, are there things that you guys have been involved in where you felt like this is a good story, people need to know about this, and somehow we're not getting anyone's attention.

Sofge: Yeah, my research is usually or, my work is usually at the kind of creating the science end of things and not so much in the outreach, but NIOSH does have a big outreach program that they are looking at and their target audience is usually employers because employers are supposed to be the ones who keep their employees safe, so they're supposed to put things in place that protect workers. So we do some direct outreach to workers and you're right, we get mixed results with that. We have some studies where we're looking at say, ironworkers who are trying to prevent falls because ironwork is one of the most hazardous occupations in the country and the falls, or near-falls are very unreported because there's an element of pride in the job and you don't want to admit that you've had an incident. So trying to get at that psychology and get to the ironworkers or to any occupation and really put it in terms that are meaningful to them. It's a whole issue, and there is push-back on things because people get familiar with what they do every day and they don't recognize the risks.

Long: You're listening to Stats and Stories, and we're focusing this time on the issue of chemical exposure in the workplace. I'm Bob Long and again our regular panelists are Miami University Statistics Department Chair John Bailer and Media, Journalism and Film Chair Richard Campbell. Our special guest is Chris Whittaker Sofge of the National Institute of Occupational Safety and Health. For our topic today, we also had another question for folks on the street: What kinds of health problems they thought of as being caused by inhaling chemicals in the workplace?

Woman on the street #5: It could cause like obviously lung issues and things like that but then also just like cancer, depending on what type of chemical you're exposed to.

Woman on the street #6: I think they face brain damage with like any lobe of their brain, depending on what the chemical is. Also asthma and like any damage to your vocal cords.

Man on the street #2: I'm sure there are risks of heart disease, lung disease, probably an endless list of possibilities.

Woman on the street #7: If you inhale them, probably lung problems. It might affect your breathing or anything that has to do with speaking. Or they could also deal with like skin rashes, problems with skin or brain damage even.

Woman on the street #8: If someone has asthma or allergies that could be a really big problem if there are unknown chemicals they aren't aware of, or health risks they're not aware of for cancer-causing chemicals.

Long: And I kind of wanted to get into that for you as well today, Chris, in terms of not just workers, but we also realize that sometimes the air we breathe, there can be problems. Is that something NIOSH has done a lot of research on as well?

Sofge: Yes, and the kinds of health effects that you could have from inhaling chemical hazards range anything from cancer, which everybody is worried about, to irritation and could be some neurological issues, we could have reproductive hazards. Everything you could think of, every system of the body could fail. If you inhale a chemical that has those effects, you could have problems with those. So one way to think about it, we have a chemical called 1-bromopropane, which is a solvent and in dry cleaning you, the typical dry cleaner uses perchlorethylene which gives that dry cleaning smell when you bring your clothes home, but perchlorethylene gets into ground water and is an environmental hazard, so companies have started replacing perchlorethylene with 1-bromopropane in their shops, and that's much more environmentally friendly because it doesn't get into the groundwater and have all those problems, but the problem is that 1-bromopropane is a neurotoxin, a reproductive toxin, and it causes cancer, and we've had some incidents where dry cleaners that have switched over their shop to 1-bromopropane have ended up in the emergency room with tremors, problems walking, and things like that and we really don't want to see that. When we're trying to work with the EPA and others that are worried about the environment, make sure that when you're moving from an environmentally hazardous chemical to another chemical that's more environmentally friendly, you're also considering the worker as part of the environment.

Long: John Bailer, we'll go to you for the next question.

Bailer: As a follow-up to that, you're describing replacing something that's known to be bad in one context with something that you think is not going to be so bad. So this is something, there has to have been a decision made in the absence of perfect knowledge. So there's a decision making in the face of uncertainty component to what's being described here. With something like the chemical replacement PERC that you described for the dry cleaners, what was not known or what data were not available that would have helped with maybe leading to more, maybe safer exposure level being set in advance?

Sofge: Yeah, and I think that was a good example of where the government lags behind where industry is moving to. And the only information we had about 1-bromopropane at the time, well we had the toxicology studies, but the agencies hadn't set exposure levels at that time because 1-bromopropane was actually used, was on the EPA list to replace ozone depleting chemicals. So it was used as a substitute for those chemicals. Now dry cleaning perchlorethylene is not one of the situations, but when they found out they could use 1-bromopropane, they used that there. NIOSH is now developing a recommended exposure limit for 1-bromopropane as part of its program to address that problem, EPA is also looking into 1-bromopropane because it's a hazardous chemical as well and it just has different effects and because it's marketed for one thing or another, it doesn't mean it's safe.

Long: Richard Campbell we'll go to you.

Campbell: In looking at some of the history of NIOSH over the years, I know carcinogen research goes way back and this is connected, sort of, with one of the problems that daily journalists have is any kind of sort of historical memory over time, journalists are really good at talking about what happened yesterday and what's happening right now. But can you talk about some of the significant changes in carcinogen research and how it affects workers since the mid-'70s.

Sofge: Yeah, NIOSH was created in 1970 and at the time carcinogen research was just getting full steam ahead and so that was the number one hazard of concern. You had at the Food and Drug Administration they were dealing with the Delaney Clause which prohibited carcinogens in food, or had zero tolerance for carcinogens in food. The agencies wanted to have zero exposure for chemicals that caused cancer and that's a reasonable thing to do in the absence of knowledge. In reality, so many chemicals cause cancer in laboratory animals and probably in humans as well that it's impossible to remove all of them from our environment. So you have to deal with some level of risk in there. I think our understanding of chemical exposures that lead to cancer have evolved over the years so now we're trying to look at what are acceptable levels of carcinogens in our air or in our food or in our water, rather than trying to focus on eliminating them all because that seems to be kind of impossible.

Long: We have time for probably one or two more questions, so John Bailer; I'll go to you next.

Bailer: Thank you. The issue that comes to mind for me, as you said there, the development of the recommended exposure level of something that's going to be occurring. Can you talk about some of the data and the process by which the data are collected, the data are considered, and then somehow integrated in a way to make recommendations at these levels.

Sofge: What we do is, at NIOSH, sometimes we collect our own epidemiology data. We go out in the field and do our studies and work our populations and measure health effects and measure exposures and get data that way, but for many chemicals we don't have that level of information. So then we have animal studies that we look at and if we're really lucky we have both animal studies and human studies that we look at and we can draw on. And so once we collect that data and look at what the health effects are there, we look at which time of health effect would be most sensitive, would cause the most problems for an individual. And we look at what concentrations of chemicals cause the health effect and construct what we call an exposure response curve. And then we look at the uncertainty around that estimate because if you're estimating something from an animal study, you have a different level of confidence than you do from a human study, and there are all sorts of other pieces that go in there, but basically then we take that and we estimate what a human exposure would be and it in this case it would be workers exposed. We assume forty hours a week for a working lifetime if we're looking at chronic disease. Now we can also look at short-term exposures and look for health effects like irritation to the nasal passages and stuff or we can look at all different levels of exposure. That's how we do it.

Long: Our special guest today has been Chris Whitaker Sofge of the National Institute for Occupational Safety and Health, better known as NIOSH, where she is the chief of the risk evaluation branch. I bet people have a different take on this after today and I really want to thank you very much for joining us today, Chris.

Sofe: Thank you.

Bailer: Thank you, Chris.

Campbell: Thanks, Chris.

Long: And if you'd like to share your thoughts about our program you can send us an email to Be sure to listen for future editions of Stats and Stories where we'll always talk about the statistics behind the stories and the stories behind the statistics.