05 Aug NYU Researcher Discusses Nanoparticles in Sunscreens and E-Cigs
MedicalResearch.com Interview with:
Judith T. Zelikoff, PhD, Professor
Department of Environmental Medicine
NYU Langone Medical Center.
MedicalResearch.com: Would you tell us a little about yourself?
Response: I am a tenured full professor in the Department of Environmental Medicine at the NYU School of Medicine with >25 years of experience studying the toxicology of inhaled single contaminants and complex mixtures including metals, nanoparticles, gaseous and particulate (PM) air pollutants, e-cigarettes and combustible products from cigarettes, biomass burning, and diesel exhaust. Over the last decade, studies in my laboratory has focused on the effects of maternal inhalation of environmental toxicants, including fine-sized ambient particulate matter during pregnancy (and/or during neonatal development) on fetal cardiovascular structure, obstetric consequences, and later life disorders including obesity, immune dysfunction, and decreased sociability and reproductive success in adult male and female offspring. Other early life studies associated with inhaled nicotine/tobacco products have demonstrated that maternal and neonatal exposure of mice to aerosols from e-cigarettes (with and without nicotine) alters neurodevelopment and produces hyperactivity in adult male offspring.
Our studies with smokeless tobacco products demonstrate dyslipidemia and non-alcoholic steatohepatitis in prenatally exposed adult offspring. One of my major scientific accomplishments are my early life inhalation exposure studies demonstrating, for the first time in some cases, that prenatal/neonatal exposure to environmental agents can produce effects persistent into adulthood that can increase susceptibility to a variety of disorders, including cardiovascular disease. In addition, I serve as the Community Outreach and Engagement Core (COEC)Director for our NYU NIEHS Core Center. In this regard, our COEC team partners with environmentally-impacted communities in the NY/NJ area to assess community concerns associated with environmental pollution and provide educational information that can help build community infrastructure. I am also extremely active as a leader in the Society of Toxicology having served as Secretary of the Society for 3 years and President of the Metals and Immunotoxicology SOT Specialty Sections where i received an Immunotoxicology Lifetime Achievement Award.
I currently serve as Chairperson of the SOT Committee for Diversity Initiatives and President of the Ethical, Legal and Social Specialty Section. I am currently a full member of a National Institute of Health Study and have also served on several other Federal/State Advisory Panels including the Institute of Medicine and National Research Council, EPA, NASA, NTP, and NJ Department of Environmental Protection. In addition to serving as an Associate Editor and Editorial Board member for numerous toxicology/environmental health journals, I currently serve as vice-President for the NYU School of Medicine Faculty Council.
MedicalResearch.com: How did you become interested in the effects of inhaled toxicants on immune system function and the reproductive process?
Response: My doctoral training was in cellular immunology so immunology was a long-time interest that I applied to my post-doctoral work in air pollution toxicology. In the past, pulmonary immunology was not a well studied field, but it seemed the right direction for me. I combined my doctoral and post-doctoral training with by microbiology background and found myself in a new discipline called immunotoxicology. With the arrival of a new graduate student over a decade ago who had an interest in maternal and child health and tobacco use, we began studies in the emerging area of developmental immunotoxicology. Our studies demonstrated that maternal exposure to relevant levels of inhaled cigarette smoke increased tumor susceptibility of the juvenile offspring, with the males being at greater risk than the females. The findings also demonstrated the role of testosterone in increasing cancer risk in the male offspring and the role of cytotoxic T-lymphocytes in bringing about these effects. More recent developmental studies have focused on the concept of developmental origins of adult disease, as well as on obstetric consequences including low birth weight and preterm delivery following inhalation exposure to metal oxide nanoparticles, particulate air pollution and alternative tobacco products.
MedicalResearch.com: What are nanoparticles?
Response: The simple answer is that a nanoparticle (or nanopowder or nanocluster or nanocrystal) is a microscopic particle with at least one dimension less than 100 nanometers; but, it is more complicated than that as is all particle technology. Nanoparticle research is currently an area of intense scientific research, due to a wide variety of potential applications in biomedical, optical, and electronic fields.
MedicalResearch.com: What is the potential effect of nanoparticles on health when inhaled?
Response: The potential impact of inhaled nanomaterials on public health is limited and depends upon a wide variety of factors such as chemical make-up, size, surface chemistry, shape and factors influencing their fate in the lungs. Due to the attractive properties of nanomaterials, such as high strength, conductivity, solubility, durability and reactivity, they have been used in a variety of applications, including fillers, opacifiers, catalysts, semiconductors, cosmetics, microelectronics, and drug carriers. Unfortunately, knowledge concerning public health implications lag behind their usage.
MedicalResearch.com: Is there any cause for concern regarding nanoparticles in skin care products (ie zinc in sunscreens)?
Response: Nanoparticles in American sunscreens are either titanium dioxide or zinc oxide. The use of nanoparticles in cosmetics poses a regulatory challenge because the properties of nanoparticles may vary tremendously, depending on their size, shape, surface area and coatings. Many studies including those by the FDA and the European Union examined the issue of skin penetration or dermal absorption. These studies have concluded that nanoparticles applied to the outermost layer of skin (strateum corneum) which is made up of dead cells do not penetrate the skin and do not harm living skin tissue. Additionally, in sunscreen formulas, it appears that nanoparticles tend to clump together to form larger-than-nano-sized particles. Studies have also indicated that the use of particle surface coatings by sunscreen manufacturers dramatically reduce the potential for photoactivity. However, inhalation of these same nanoparticles could potentially pose a pulmonary risk and thus consideration should be given for the use of loose powder makeup or spray sunscreens using titanium dioxide of zinc oxide.
MedicalResearch.com: Can you explain how an e-cig differs from a regular cigarette?
Response: Electronic cigarettes turn nicotine and other chemicals into an aerosol that’s inhaled by the user and then exhaled. With most e-cigs, you have a few internal components- a battery, an atomizer and a tank. The tank is where the liquid goes. You fill the tank with the liquid of your choice then place it inside the e-cigarette. Once you power on the cigarette, the atomizer will heat up and warm the liquid. The liquid will quickly turn into an aerosol, which you inhale and exhale. Just one of the battery-powered devices provides as many as 300 puffs, roughly equivalent to the number of drags from an entire pack of conventional cigarettes. The smoker inhales a mix of water vapor and nicotine among other chemicals including propylene glycol, glycerine and flavorings. E-cigarettes are heated and not burned like regular cigarettes and thus do not generate tar, ash or carbon monoxide. In terms of cost, e-cigarettes are cheaper than traditional cigarettes. In lots of countries, normal cigarettes are banned whereas e cigarettes are gaining popularity. In contrast, a cigarette is any roll of tobacco wrapped in paper or in any substance not containing tobacco. Tobacco smoking is the practice of burning tobacco and inhaling and exhaling the smoke that consists of particles and gasses. As a result of tobacco combustion, the resulting smoke contains more than 7,000 chemicals, hundreds of which are known toxicants and about 70 are known carcinogens. Nonsmokers who are exposed to secondhand smoke at home or work increase their lung cancer risk by 20–30%. For all of the differences between e-cigarettes and regular tobacco cigarettes, e-cigarettes still contain nicotine, which is addictive, and it is unclear exactly how much nicotine the e-cigarette smoker actually inhales.
MedicalResearch.com: Are there different/fewer/more toxins released by e-cigs?
Response: E-cigarettes lack tar (the resinous, partially combusted particulate matter produced by tobacco combustion during the act of smoking), carbon monoxide and tobacco (except when tobacco flavorings are used). While the toxicity and/or carcinogenicity of the inhaled/exhaled products of tobacco smoke are well-known and well-studied, toxicological data on e-cigarettes are limited. While the number of toxic agents released from e-cigarettes appear to be far fewer than the 7,000 released from tobacco smoking, the safety of the components via the inhalation route of exposure from e-cigarettes are relatively unknown. In lieu of tobacco, e-cigarettes typically contain three main ingredients: nicotine, a flavoring of some kind (currently >7,000 flavorants available) and propylene glycol—a syrupy synthetic liquid added to food, cosmetics, and certain medicines to absorb water and help them stay moist. While propylene glycol is “generally regarded as safe” by ingestion, its safety when inhaled is questionable based on the results of limited studies. Moreover, evidence is rapidly accumulating concerning the health effects of the flavorings, particularly those associated with the cinnamon flavors. Findings from our recently-published toxicological studies demonstrate that exposure of an animal model during pregnancy and early in neonatal life to e-cigarette aerosols with and without nicotine, alters gene expression important in neurodevelopment and induces hyperactivity in the offspring later in life. Our studies also reveal that components other than nicotine drive these adverse neurological effects. Moreover, a recently released study indicates that vaping e-cigarettes is associated with decreased expression of a large number of immune-related genes, which are consistent with immune suppression at the level of the nasal mucosa in humans. Thus, while far fewer toxins are released by e-cigarettes than tobacco cigarettes, their safety via the inhalation route are not clear.
MedicalResearch.com: Do e-cigs cause more or less addiction to nicotine? Are young people or others who may not have smoked previously, now trying e-cigs thinking they are safe?
Response: The science is still out as to whether nicotine from e-cigarettes are more, less or the same in terms of their addictive nature. While a recent study shows it is less addictive, other studies claim they are more addictive due to the type of nicotine being used for these products. The data are also conflicting as to whether e-cigarettes serve as a way out of tobacco smoking or a gateway into smoking. However, there is no doubt that e-cigarette use has risen dramatically over the last few years and that many of the users are adolescents and young adults. While e-cigarettes may be considered “safer” than regular cigarettes, the question of “safe” requires further scientific studies. What I can say, is that based upon our studies with e-cigarettes and pregnant hosts, women should think long and hard about “vaping” while pregnant.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: A lot more scientific research is needed before we can accurately predict the public health risk (if any) of e-cigarettes. More studies are needed on the individual e-cigarette components, added flavorants, those components not listed on the packaging, as well as on the inhaled aerosol itself and secondhand exposure.
MedicalResearch.com: Is there anything else you would like to add?
Response: Their popularity of e-cigarettes is growing. The CDC states that 2 million high-school students reported using e-cigarettes at least once in the month before the survey. The WHO reported that in 2013, more than $3 billion was spent on e-cigarettes in the US alone and it predicts that sales will increase 17-fold in 15 years. While e-cigarettes appear to be extremely helpful for current smokers, more research is needed for a more accurate safety assessment.
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