Flight Attendant Research on Harvard Gazette

The flight attendant research led by Dr. Eileen McNeely, funded by the Hoffman Pilot Program, is featured in the Harvard Gazette today:









Health at 35,000 feet
The health risks faced by flight attendants, who work outside standard health and safety protections, piqued the interest of researchers. Click HERE to read the full story.





The Continual Regrettable Substitution of Nail Polish Ingredients

Written by Anna Young, edited by Diana Ceballos

“We only buy ‘safe,’ ‘non-toxic’ nail polishes for our salon. They’re all ‘6-Free,’” announced Tiffany, a nail salon employee in the Boston area. But the nail polishes are not non-toxic: every day Tiffany faces complex, and often subtle, toxic exposures. Unfortunately, as a manicurist in the primarily young, female, and Vietnamese nail salon workforce, Tiffany is continuously at risk of reproductive harms, respiratory damage, sensitization, and other health effects.

Investigating Tiffany’s uncharted exposures required detective-esque sleuthing to uncover the full ingredient compositions of various nail polishes, the validity of “6-Free” and other product labels, and the strength of government cosmetics regulation. So I understand Tiffany’s misplaced confidence and trust. She does not know about the inadequate regulation of chemicals and labels, the toxicity concerns of currently used ingredients, or the continual substitution of toxic chemicals for other toxic chemicals. Product information is complex, confusing, and often unavoidably misleading.

In pursuit of learning the chemical compositions of commonly used nail polishes, I first analyzed the ingredients listed on Safety Data Sheets (SDS), which are product chemical hazard information sheets required in nail salons by the Occupational Safety and Health Administration. As I discovered, these SDSs typically only list a handful of ingredients. Brands can avoid disclosure of other potentially hazardous chemicals if the ingredients are trade secrets or below levels that trigger SDS disclosure requirements.

Dismayed at the unhelpfulness of SDSs, I turned to ingredient labels for nail polish products sold to consumers—ingredient lists which are not required by the Food and Drug Administration when the same products are professionally used in nail salons. These labels provide much longer lists of chemicals, many of which have toxicity concerns, compared to the corresponding SDS, demonstrating the inadequacy of SDS health information available for nail salon employees. However, despite their comprehensiveness, the consumer ingredient labels can result in confusion, too. For example, the Food, Drug, and Cosmetic Act of 1938 allows some ingredients to simply be listed as “fragrance” on the label. Diethyl phthalate, a widely concerning reproductive toxic chemical and plasticizer, is one such ingredient.

Nail salon employees and consumers (and even us researchers!) typically don’t understand all the chemicals listed on ingredient labels. Instead, many health-conscious nail polish purchasers look to marketing labels. “Safe,” “Natural,” and “Non-Toxic” labels exude safety reassurance and trustworthiness. Can we really trust these labels?

The answer is uncertain. Many nail polish companies have proactively eliminated concerning ingredients in the face of a seemingly never-ending string of chemicals found to be toxic. For example, in the past decade, most brands got rid of the widely publicized “Toxic Trio” chemicals (dibutyl phthalate, toluene, and formaldehyde) and now advertise “3-Free” nail polish. However, although “safer” nail polish brands may have removed a few toxic chemicals, they still contain other concerning ingredients. In addition, there is no reliable, comprehensive source on the myriad of evolving nail polish labels and their implications for health.

Recent progress from “3-Free” to “10-Free” labels seems both hair-raising (why were those toxic chemicals in the products in the first place?) and promising (toxic chemicals have been removed!). But the evolving labels may provide false reassurances in some instances. Instead of the “Toxic Trio” plasticizer dibutyl phthalate, many nail polishes now contain an alternative plasticizer, triphenyl phosphate, which also has reproductive toxicity concerns. Furthermore, these labels are not always accurate. The California Department of Toxic Substances Control found in 2012 that 5 of 7 “3-Free” nail polishes that they tested did actually contain one of the “Toxic Trio.” The market for “safe” nail polishes has become impossible to fully understand and navigate.

My research endeavors to fully unravel nail polish composition, to no avail, reinforces the inherent problem with product chemical safety: the burden of safe nail polishes should not be on the consumer, nail salon, or employee. A fellow nail salon employee of Tiffany’s should not have to confess, with instinctive suspicion, “I’d rather not know” when offered information about the reproductive toxic chemical exposures sampled in her nail salon. And her employer should not be faced with only one option to switch to safer (and naturally, more expensive) nail polish products: introducing higher service prices that most customers would not be willing to pay.

In a country with no required premarket approval of nail polish products (except for color additives) and fewer than a dozen banned or restricted chemicals in cosmetics, compared to the European Union’s more than 1600, we desperately need to update our 1938 federal regulation of chemicals in cosmetics. We must promote safe ingredients at the design stage of products to protect consumers and workers alike. Meanwhile, as consumers, we can encourage industry to investigate safer alternative ingredients, and we can strive to make the best choices with the little information we have.

* If you are a manufacturer or distributor of nail polish you can help us in a research study! We would welcome nail polish samples sent to us – please contact Anna at ayoung@mail.harvard.edu. In a current pilot project funded by the Harvard Education and Research Center, we are chemically analyzing as many nail polish brands as possible for plasticizers and metal contaminants to inform safe ingredient alternatives.     

Note: Name of nail salon employee has been changed to protect privacy.



California Department of Toxic Substances Control. 2012. Summary of data and findings from testing of a limited number of nail products.

EUR-Lex: Access to European Union Law. 2011. Council Directive of 27 July 1976 on the approximation of the laws of the Member States relating to cosmetic products.

Meeker J, Cooper E, Stapleton H, Hauser R. 2013. Exploratory analysis of urinary metabolites of phosphorus-containing flame retardants in relation to markers of male reproductive health. Endocrine Disruptors 1: 1-5.

Meeker J, Stapleton H. 2010. House dust concentrations of organophosphate flame retardants in relation to hormone levels and semen quality parameters. Environmental Health Perspectives 118: 318-323.

Mendelsohn E, Hagopian A, Hoffman K, Butt C, Lorenzo A, Congleton J, Webster T, Stapleton H. 2016. Nail polish as a source of exposure to triphenyl phosphate. Environment International 86: 45–51.

U.S. Food and Drug Administration. 2013. Cosmetics: laws and regulations; nail care products; fragrances in cosmetics; color additives and cosmetics.

Formal E-Recycling: The Complexity of Solving the E-waste Problem Worldwide

Written by Diana Ceballos and Zhao Dong, edited by Marcy Franck

Mounting e-waste (image from mikebiddle.com)
The mounting e-waste (image from mikebiddle.com)

At seven o’clock each morning I wake up to my electric alarm clock. I turn on the radio, and then go into the kitchen to make coffee, pop some bread in the toaster and heat up some milk in the microwave. When I’m ready to head out, I put on my watch and check to make sure my cell phone and earphones are in my purse. This is what my typical morning looks like and, increasingly, what a typical morning of anyone in the modern age looks like as well.

Our lives are inundated with electronics and appliances that either plug into the wall or use batteries. Our homes, cars, and workplaces are equipped with a multitude of gadgets and devices that provide comfort and functionality to all dimensions of our lives, and we have become dependent on them.

E-waste is a Worldwide Problem

E-waste is growing at an alarming rate worldwide, faster than it can be recycled. The e-recycling industry is fairly new and faces many challenges to keeping up with the different types of electronics, brands, and influx of items that are recyclable, and maintaining standards that keep workers healthy and the environment clean is an ongoing challenge worldwide.

The process for recycling electronics involves dismantling them into valuable materials that can be resold, and the process can be a source of toxic chemical pollution that harms workers, communities, and the environment near the facilities. The process can also release metals such as cadmium, lead, mercury, and nickel, and organic compounds such as flame retardants, and polychlorinated biphenyls into the environment. The amount of harm done depends on whether a formal or informal e-recycling business is performing the work.

Developing countries tend to recycle e-waste at informal e-waste sites inside homes and in back yards, and the conditions are dire. The health of workers—including child laborers—and people in nearby communities can be adversely impacted by the multitude of toxic chemicals present. It’s common to find respiratory problems, babies with birth defects, among other health problems in or around these informal sites.

Developed countries generally use formal e-recycling facilities, which tend to be larger and have better controls for health and environmental protection. These facilities usually refurbish, resell, or dismantle and shred electronics into separate recyclable materials, such as plastic and metal.

 Formal E-Recycling Facilities on the Rise

In the last few years, developing countries like Colombia and China have established formal e-recycling facilities, moving e-waste indoors with varying degrees of protection from hazardous materials. Therefore, I worked with my colleague Zhao Dong, both of us researchers with the Hoffman Program on Chemicals and Health at the Harvard T.H. Chan School of Public Health, to question if transforming informal e-recycling businesses into better-controlled e-recycling facilities would solve the environmental and occupational health problems typical of the informal recycling sites.

To learn about the current conditions of formal e-recycling facilities worldwide in terms of the health of their workers and their environment, we reviewed the literature and published our findings in the Environmental International journal, in a short review article “The Formal Electronic Recycling Industry: Challenges and Opportunities in Occupational and Environmental Health Research”.

Challenges Faced by Formal Electronic Recyclers

We found that the formal e-recycling industry is still very new, as is the research on the topic. The earliest publications dated back to 1999, and 21 (81%) of the publications reviewed were published after 2013. The past two decades covers the informal sector quite well, but there is a dearth of papers documenting conditions in the formal sector— we found 37 in total, including government reports.

Despite limited studies on the topic, our findings are interesting and concerning. Our review suggests that worker exposures to metals were often higher than recommended occupational guidelines. Levels of brominated flame-retardants in workers’ inhaled air and biological samples were higher than those from reference groups. Air, dust, and soil concentrations of metals, brominated flame-retardants, dioxins, furans, polycyclic-aromatic hydrocarbons, or polychlorinated biphenyls found inside or near the facilities were generally higher than reference locations, suggesting transport into the environment. Lastly and most concerning, children of a recycler had blood lead levels higher than public health recommended guidelines because of the dust brought from work to home. This tells us that there are still issues to be addressed in the formal e-recycling industry despite the improved environmental and occupational health conditions compared to those in the informal sector.

Setting a Research Agenda Focused on Health

In our review, we discuss challenges and opportunities in occupational and environmental health research in this area and identify research needs to further assess exposures, health, and improve controls. We recommend that the long-term solution is to manufacture electronics without harmful substances while designing them with easy-to-disassemble components.

How Can We Solve the E-waste Problem?

The e-waste problem is an international issue and is very complex. Strengthening the formal e-recycling industry will help to improve the health of workers and the community of e-recyclers worldwide, and when done appropriately, provides one of the solutions to the problem. What’s more, each of us consumers can also contribute and become part of the solution.

These are small actions that we could all take to make a difference:

  • Do not throw away electronics or electrical equipment including batteries, light bulbs, and solar panels into the regular garbage. Many work places collect these items separately. For homes, residents can explore the many well-established e-waste collections, take back programs, or processing facilities. These services are usually free, although it depends on your state and the item to be recycled. To find the best collection programs or the closest e-waste processing facility near you, you may check government websites or your local health department. Alternatively, look for the nearest processing facility by visiting the electronic recycling industry certification websites—some examples are: http://e-stewards.org/find-a-recycler/, https://sustainableelectronics.org/recyclers.
  • Support electronic recyclers in your community. You can usually dispose of your e-waste by visiting these facilities or go to free community collection days.
  • Do not buy electronics or electrical appliances that you do not need. Upgrade your phones and electronics less frequently.
  • Support electronic and electrical equipment manufacturers that use green technologies and have take back programs.

Are “Green” Dry Cleaning Solvents Bad for Our Health?

by Diana Ceballos and Marcy Franck


Sometimes chemicals we call “green” are better for the environment, but not always good for our health. Dr. Diana Ceballos, our Visiting Scientist with the Hoffman Program on Chemicals and Health, and some of her research colleagues, set out to better understand how chemicals commonly used in the dry cleaning industry impact health, especially as many shops are making the switch to products thought to be better for the environment.

There are about 36,000 commercial dry cleaning shops in the United States. These shops are usually small businesses that are marginally profitable and owned and staffed by individuals with limited English proficiency. Due to these economic and logistical factors, they can have challenges maintaining a safe and healthy workplace.

To inform safe work practices that would better protect workers’ health, Dr. Diana Ceballos and her colleagues evaluated four dry cleaning shops, each using two new “green” dry cleaning solvents. They published their results in the Journal of Occupational and Environmental Hygiene (JOEH), in their article “Occupational Exposures to New Drycleaning Solvents: High-flashpoint Hydrocarbon and Butylal”.

Out with the old, in with the new

The dry cleaning industry is moving away from using the solvent perchloroethylene (PERC), because it is believed to cause cancer and can harm the nervous system, liver, and kidneys. Some of the PERC alternatives are promoted as safe and environmentally friendly, although their effects on human health and the environment are not well characterized.

Due to limited research studies, we know little about the potential human health impacts of the new alternative dry cleaning solvents Dr. Ceballos and her colleagues studied—butylal and high-flashpoint hydrocarbon solvents. Of them, we know that butylal does not suggest toxicity when exposed in the short term, but there’s no research telling us how this chemical might impact health with repeated exposures over time. The high-flashpoint hydrocarbon is a known irritant and, at high levels, can cause headaches, dizziness, drowsiness, unconsciousness, and other central nervous system effects, including death. While it’s unlikely for high-flashpoint hydrocarbons to appear at these levels in dry cleaning shops, the study seeks to better understand typical exposures of those working in close proximity to them on a regular basis.

What chemicals are in workers’ breathing zones?

Dr. Ceballos and her research colleagues collected air samples from workers’ breathing zones. They were looking for evidence of butylal and high-flashpoint hydrocarbons, and also formaldehyde, and butanol because they are potential by-products of butylal. Both are known irritants and formaldehyde is a probable carcinogen.

Air levels in all dry cleaning shops tested highest for the dry cleaning solvents when workers loaded and unloaded the dry cleaning machines and pressed dry cleaned fabrics.

The first two dry cleaning shops in the study used butylal as the cleaning solvent. Test results for these shops found butylal, formaldehyde, and butanol in workers’ breathing zones. The levels of formaldehyde and butanol measured were not of concern for worker’s health. The researchers could not determine if the levels of butylal were harmful, because there is insufficient research about the health impacts of this solvent.

The remaining two shops, each using the high-flashpoint hydrocarbon as the cleaning solvent, found high-flashpoint hydrocarbon solvents in the area where workers breathe, but they were found at levels of no concern for worker’s health.

Innovative new methods for measuring chemicals in the air

This study was important beyond assessing workers health. This is the first time that scientists measure the new dry cleaning solvents butylal and high-flashpoint hydrocarbons in dry cleaning shops. To do so, Dr. Ceballos team worked with chemists to develop a new analysis method to be able to measure butylal in air and adapted an existing method for hydrocarbons to be able to tease out the high-flashpoint hydrocarbon mixture. These methods can be used by other scientist as we learn more about these new solvents. Further, to assess the safety of butylal, Dr. Ceballos team used risk assessment tools as no occupational guidelines exists. The tools results suggested that dry cleaning workers should take precautions to avoid exposures; however, limited information on this new solvent makes the conclusions from the risk assessment tools also limited.

Understanding potential effects on human health of chemicals being used as dry cleaners is important to prevent workers’ health problems. However, there is insufficient toxicological and health information to determine confidently the safety of butylal on human health.

This lack of information can translate into uncertainty about the safety of people who wear clothes washed in these chemicals. As we support businesses using “green” chemicals because they may help the environment, it is important to acknowledge that these chemicals may be harmful. Until future research studies can measure their health impacts, we can’t be sure.

Are You Allergic to Your Job?

Written by Diana Ceballos, edited by Marcy Franck

Are you allergic to your job? (image from: communicatebetterblog.com)
Are you allergic to your job? (image from communicatebetterblog.com)

My interest in the connection between chemicals and health began when I was a high school student volunteering in a neighborhood that was built on top of an abandoned landfill in Medellin, Colombia. My position involved playing with and feeding neighborhood children, selling inexpensive used clothing, and teaching adults to read and write. It also allowed me to observe their deplorable life conditions—I could see decomposing garbage peeking through the top soil between houses, large gas plumes sporadically venting from the ground, and brown water running from kitchen faucets. I could not escape the repulsive odors creeping around every corner.

Even though I was young, I knew that the environment in which they lived made them sick. Mothers were always fatigued and coughing, while their kids looked malnourished and had skin rashes, infected wounds, and sometimes deformities. I knew then that I would devote my professional life to understanding the relationship between chemicals and health—a desire to prevent the suffering that stems from living in toxic environments pushed me to pursue scientific research. Many years later, I now study the health effects of chemical exposures in our environment, focusing on the places where we work.

We spend up to 90% of our time indoors: inside our homes, schools, and workplaces. For most of us, time spent indoors exposes us to a wide variety of chemicals, especially at work, where we are often in proximity to substances associated with day-to-day responsibilities associated with manufacturing, construction, or practicing medicine.

Even if a job doesn’t require working directly with chemicals, we may be exposed simply by spending time in areas where the chemicals are stored. Plus, we are exposed to chemicals in the materials used to construct and furnish the buildings in which we work and live. Some office or home furniture and flooring, for example, may emit low levels of formaldehyde, an irritant and sensitizer, which we may come into contact with daily.

For the most part, we are exposed to very small concentrations to the chemicals we come into contact with, and most of us do not perceive an acute reaction. However, some people develop an allergy that can lead to what we call a chemical sensitivity in my field. Sensitizers are the chemicals that are known to cause a negative reaction involving the immune system. Sensitization is the process by which a person becomes increasingly allergic to a sensitizer through repeated exposure.

The substance may cause a mild response during the first few exposures but, as the allergy develops, the response can become worse with subsequent exposures. Eventually, even short exposures to low concentrations can cause very severe reactions. People with chemical sensitivities may experience symptoms such as skin rashes, asthma, and other respiratory issues (Kimber et al. 2002 and 2011, HSE 2015a).

The implications for chemical sensitivities can be devastating to a person’s livelihood. Imagine, for example, what happens when a metal worker becomes sensitized to nickel, or a painter becomes sensitized to epoxy resins found in some paints. If symptoms improve only after reducing exposure to the chemical, one may need to find a different job or profession (HSE 2015b,c). The transition into a new career can be extremely stressful and disruptive.

It’s not only chemicals that can become sensitizers—the workplace can also expose us to other substances that can lead to sensitization. For example, hairdressers can become sensitized to latex in gloves, bakers to flour dust, and construction workers to wood dust. One of the most challenging aspects of doing research in this field is that we are rarely exposed to only one chemical or other sensitizer at a time. If this were the case, it would be relatively easy to isolate a single substance that could be at the heart of health issues that arise on site. But the nature of our indoor environment often exposes us to a multitude of sensitizers—sometimes all at once, sometimes over time, and sometimes both.

Even still, most of the research on chemical sensitivities focuses on single chemical exposures.

Through my doctoral and post-doctoral research I came to understand the challenges to preventing chemical sensitization. I interviewed many people in the automotive spray paint industry, including painters, business owners, trainers, and industry association folks who used isocyanate base coatings in their profession. I was shocked when every person I talked with knew of at least one person who had been affected by isocyanates. Some reported that their colleagues had changed work responsibilities and, more often than not, ended up doing office work instead of spray painting. I also learned about several extreme cases that resulted in severe reactions if the individual sensitized to isocyanates got too close to an auto body shop.

Later on, through my work with the National Institute for Occupational Health (NIOSH), I encountered many individuals who were highly sensitive to chemicals in their workplace, even when exposed to levels well below those that would be enforceable by regulations. In some cases, my team and I were able to provide recommendations to help with their health concerns, especially in cases where there was a clear relationship between a particular chemical exposure and health symptom. However, in most cases we were not able to help, especially when only one or two individuals reported nonspecific health symptoms. Help became even more challenging to provide when we were unable to determine if the health concerns were exclusively work-related or were also related to home, hobbies, or previous work. In many cases, those with chemical sensitivities would endure high levels of stress because their concerns were not often appropriately addressed. Many people in this situation would take long leaves of absence and eventually resign.

We need a stronger research base to better respond to the needs of individuals who are allergic to multiple substances in their environment. I am drawn to this research for the thrill of helping those who suffer by learning more about the causes behind their sensitivities, and also helping to prevent and alleviate their symptoms.

If you deal with substances at work and are unsure if you are exposed to known sensitizers, you first need to identify the chemicals you encounter. You can start by obtaining the safety data sheet and looking up the chemical ingredients at the NIOSH Pocket Guide to Chemical Hazards and check if “sensitization” is listed under symptoms.

If you think you are sensitized to a chemical or substance at your work, talk to your supervisor and work health provider for assistance.



HSE (2015a). Examples of skin irritants and sensitisers, together with occupations where they occur. http://www.hse.gov.uk/skin/professional/causes/agentstable1.htm. Accessed December 9, 2015.

HSE (2015b). Asthma. http://www.hse.gov.uk/asthma/index.htm. Accessed December 9, 2015.

HSE (2015c). Spray Painter and Isocyanate. http://www.hse.gov.uk/asthma/isocyanates.htm

Kimber I, Basketter DA, Gerberick GF, Dearman RJ. Allergic contact dermatitis. Int Immunopharmacol. 2002 Feb;2(2-3):201-11.

Kimber I, Basketter DA, Gerberick GF, Ryan CA, Dearman RJ. Chemical allergy: translating biology into hazard characterization. Toxicol Sci. 2011 Mar;120 Suppl 1:S238-68.

NIOSH (2015). Skin Exposures & Effects. Skin Notation (Sk) Profiles. http://www.cdc.gov/niosh/topics/skin/skin-notation_profiles.html. Accessed December 9, 2015.