Clinical Associate Professor of Global and Environmental Health
Dr. Chris Dickey is an international development innovator and public health entrepreneur whose work seeks to develop sustainable public health models and to forge bonds between the academic community and practitioners in the field. He sees the challenges facing public health - vast health inequities, applied skills gaps among public health professionals, weak community health systems, and shrinking research budgets - and seeks to reimagine sustainable solutions through a multidisciplinary approach. This is reflected by the fact that he has worked in more than 20 countries with the United Nations (UN) and other agencies and co-founded a company that provides clean water and primary care in villages in India.
Dr. Dickey is developing a public health entrepreneurship program to address the demand for a new generation of public health practitioners with the skill sets and opportunities to create innovative and sustainable business models as stand-alone entities or within a larger corporation.
Through a learning model that combines lectures, group exercises, real-time simulations, and implementable course projects and in partnership with the UN and World Food Programme, Dr. Dickey leads an Applied Food System and Nutrition course in which international public health professionals and public health students learn and work together on real world problems. Additionally, Dr. Dickey coordinates the Applied Global Health and Development Lab, where have the opportunity to work on universal health coverage policy, a new data-driven decision support tool, supply chain and logistics analysis, social network and knowledge management analyses, and the development of a business model for online public health programs.
DrPH, Molecular Cancer Epidemiology, Columbia University, New York, NYMBA, Finance and Entrepreneurial Management, University of Pennsylvania, Philadelphia, PAMA, Journalism, New York University, New York, NY
Global HealthInter-organizational NetworksPublic Health EntrepreneurshipSustainabilitySystems Interventions
A New Model of Learning: Environmental Health in a Global WorldRom, W. N., Rao, A., Hoepner, L., & Dickey, C. (n.d.).
Journal titleInternational journal of environmental research and public health
Issue12AbstractIntroduction. Environmental Health in a Global World at New York University was re-designed as a class participatory effort, challenging undergraduate students to understand environmental hazards and the resultant adverse health outcomes by embracing the inherent complexity of environmental risks and proposing solutions. Methods. Following introductory lectures, students are placed into teams and assigned a specific perspective, or avatar, which includes learning to see the challenge from the perspective of a technical expert such as a biologist, an engineer, or an anthropologist. The teams then design specific systems maps to visualize the complex interactions that lead to adverse health outcomes after a given environmental exposure. The maps highlight potential leverage points where relatively minor interventions can provide a disproportionate benefit in health outcomes. The teams then explore potential interventions and identify the potential unintended consequences of those actions, develop and advocate for innovative new strategies to mitigate risk and improve outcomes. Results and Discussion. Over the past 5 years, we have taught this methodology to over 680 students with strong, student-oriented results. The teams created and presented more than 100 strategies, addressing a diverse set of environmental challenges that include water contamination, gun violence, air pollution, environmental justice, health security, and climate change. Developing the strategies helped the students understand environmental threats in a more holistic way, provided them with some agency in finding solutions, and offered an opportunity for them to improve their presentation skills. The responses in course evaluations have been enthusiastic, with many students reporting a deep impact on their college experience.
Behavioral Communication Strategies for Global Epidemics: An Innovative Model for Public Health Education and Humanitarian ResponseDickey, C., Holzman, E., Bedford, J., Manoncourt, E., Shirky, C., Petit, V., Guirguis, S., Bloch, K., & Obregon, R. (n.d.).
Journal titleHealth promotion practice
Page(s)448-452AbstractIn response to a number of growing global health challenges, New York University and UNICEF designed a Behavioral Communication Strategies for Global Epidemics course that brings together United Nations professionals, government staff, and MPH (Master of Public Health) students to design innovative social behavior change communication (SBCC) strategies that address disease outbreaks and humanitarian challenges around the world. Applying a systems approach, participants in the course work on interdisciplinary teams to design strategies, develop skills, and engage in global learning. At the culmination of the course, all teams present strategies to UNICEF country offices for implementation. This innovative model for disease outbreak, public health education, and humanitarian response provides professionals with an opportunity to develop a wide range of competencies, including systems thinking, behavior change, and human-centered design and equips them with the necessary tools to develop more novel approaches to SBCC. As the number of outbreaks and humanitarian challenges increase each year, this format for learning can serve as a model for how professionals can effectively address these complex crises.
Addressing equitable access through innovation: case studies from Ghana, Uganda and Rwanda.
Integrating an approach to assess UHC access barriers into district health systems strengthening in Uganda, Ghana and Rwanda.Dickey, C., O’Connell, T., Bedford, J., & Thiede, M. (n.d.). (1–).
What would it really take to halt Ebola and prevent future epidemics?Healton, C., & Dickey, C. (n.d.).
Journal titleThe Huffington Post
Re: Hemminki,K., Dickey,C., Karlsson,S., Bell,D., Hsu,Y., Tsai,W.-Y., Mooney,L.A., Savela,K. and Perera,F.P. (1997) aromatic DNA adducts in foundry workers in relation to exposure, lifestyle and CYP1A1 and glutathione transferase M1 genotypePerera, F., Tsai, W. Y., Dickey, C., & Hemminki, K. (n.d.). In Carcinogenesis (1–).
Aromatic DNA adducts in foundry workers in relation to exposure, life style and CYP1A1 and glutathione transferase M1 genotypeHemminki, K., Dickey, C., Karlsson, S., Bell, D., Hsu, Y., Tsai, W. Y., Mooney, L. V. A., Savela, K., & Perera, F. P. (n.d.).
Page(s)345-350AbstractLevels of aromatic DNA adducts in foundry workers and controls were followed at four annual samplings. During this time exposure to polycyclic aromatic hydrocarbons (PAH) decreased and the level of DNA adducts decreased accordingly. In the total group exposure was related to the level of adducts. Adduct levels correlated with urinary 1-hydroxypyrene (LOGU1OH), air benzo[a]pyrene, weekly working hours and daily cigarette consumption. In a multivariate model 1-hydroxypyrene had a consistent effect. Neither glutathione transferase M1 (GSTM1) nor cytochrome P450 1A1 (CYP1A1) genotypes had clear effects. Yet the individuals lacking GSTM1 had a stronger effect of LOGU1OH and some effect by other sources of PAH, such as charcoal broiled food, although all these variables were not significant in the multivariate model. The rare individuals with a CYP1A1 polymorphism MspI containing an amino acid change at isoleucine had an increased level of adducts. The results showed that the postlabelling method used was able to detect an increase in aromatic DNA adducts in leukocytes when exposure to benzo[a]pyrene in air was ~5 ng/m3. At such low levels smoking and charcoal broiled food may be important contributors to adducts.
Molecular epidemiology and occupational health
Variability in PAH-DNA adduct measurements in peripheral mononuclear cells: Implications for quantitative cancer risk assessmentDickey, C., Santella, R. M., Hattis, D., Tang, D., Hsu, Y., Cooper, T., Young, T. L., & Perera, F. P. (n.d.).
Journal titleRisk Analysis
Page(s)649-656AbstractBiomarkers such as DNA adducts have significant potential to improve quantitative risk assessment by characterizing individual differences in metabolism of genotoxins and DNA repair and accounting for some of the factors that could affect interindividual variation in cancer risk. Inherent uncertainty in laboratory measurements and within-person variability of DNA adduct levels over time are putatively unrelated to cancer risk and should be subtracted from observed variation to better estimate interindividual variability of response to carcinogen exposure. A total of 41 volunteers, both smokers and nonsmokers, were asked to provide a peripheral blood sample every 3 weeks for several months in order to specifically assess intraindividual variability of polycyclic aromatic hydrocarbon (PAH)-DNA adduct levels. The intraindividual variance in PAH-DNA adduct levels, together with measurement uncertainty (laboratory variability and unaccounted for differences in exposure), constituted roughly 30% of the overall variance. An estimated 70% of the total variance was contributed by interindividual variability and is probably representative of the true biologic variability of response to carcinogenic exposure in lymphocytes. The estimated interindividual variability in DNA damage after subtracting intraindividual variability and measurement uncertainty was 24-fold. Inter- individual variance was higher (52-fold) in persons who constitutively lack the Glutathione S-Transferase M1 (GSTM1) gene which is important in the detoxification pathway of PAH. Risk assessment models that do not consider the variability of susceptibility to DNA damage following carcinogen exposure may underestimate risks to the general population, especially for those people who are most vulnerable.
Molecular epidemiology in environmental carcinogenesis
CYP1A1 Messenger RNA Levels in Placental Tissue as a Biomarker of Environmental ExposureWhyatt, R. M., Garte, S. J., Cosma, G., Bell, D. A., Jedrychowski, W., Wahrendorf, J., Randall, M. C., Cooper, T. B., Ottman, R., Tang, D., Tsai, W. Y., Dickey, C. P., Manchester, D. K., Crofts, F., & Perera, F. P. (n.d.).
Journal titleCancer Epidemiology Biomarkers and Prevention
Page(s)147-153AbstractThe human CYP1A1 gene codes for an inducible enzyme system involved in biotransformation of certain xenobiotics, including polycyclic aromatic hydrocarbons; some of the metabolites are carcinogenic and mutagenic. Effects of environmental exposures (smoking, air pollution, and diet) on CYP1A1 gene induction in placental tissue and the modulation of induction by the CYP1A1 Mspl RFLP were evaluated in two groups from Poland: 70 mother-child pairs from Krakow, a city with elevated air pollution; and 90 pairs from Limanowa, a less polluted area. Compared to placentas from nonsmoking women, CYP1A1 mRNA levels were significantly increased in placentas from current smokers (P < 0.001). Ex-smokers also had significantly higher placental mRNA levels, including women who quit smoking prior to pregnancy (P < 0.01). A marginal increase in CYP1A1 mRNA with environmental tobacco smoke exposure was evident. Within Krakow, there was an increase in CYP1A1 mRNA with ambient pollution at the place of residence for each woman, which was significant among women who were not employed away from the home (P < 0.05 controlling for smoking status, diet, and use of coal for heating). Significant increases in mRNA were associated with dietary consumption of smoked meat, cheese, and fish (P < 0.01). The CYP1A1 Mspl RFLP was not a significant determinant of CYP1A1 mRNA levels after controlling for smoking and other variables. Human placenta provides a readily available and responsive system that can serve as a model for evaluating environmental and genetic determinants of CYP1A1 induction.
Carcinogen-DNA adducts and gene mutation in foundry workers with low-level exposure to polycyclic aromatic hydrocarbonsPerera, R. R., Dickey, C., Santella, R., O’neill, J. P., Albertini, R. J., Ottman, R., Tsai, W. Y., Mooney, L. A., Savela, K., & Hemminki, K. (n.d.).
Page(s)2905-2910AbstractCarcinogen-DNA adducts and somatic gene mutation at the hypoxanthine guanine phosphoribosyl transferase (HPRT) locus were evaluated in peripheral leukocytes of workers in an iron foundry with exposure to benzo[a]pyrene (B[a]P) and other polycyclic aromatic hydrocarbons (PAHs). During the two year study period, B[α]P exposure declined by ∼40%, from a maximum of 60 ng/m3 in the first year to <36 ng/m3 1 year later. A total of 64 persons were sampled in November/December of the two successive study years; 24 of them gave two samples one year apart. The biomarkers included carcinogen-DNA adducts in leukocytes (PAH-DNA measured by an immunoassay, aromatic-DNA by the 32P-postlabeling method) and HPRT mutation in lymphocytes. After adjusting for smoking, levels of PAH-DNA, aromatic-DNA and HPRT mutation frequency (Mf) increased with exposure among the 64 workers sampled during the 2 year period (P ≤ 0.05). However, the markers showed a differential response to the change in exposure, consistent with their individual biology. For example, among the 24 workers sampled in both years, carcinogen-DNA adducts (which have a halflife on the order of several months) were markedly reduced from the first to the second year (PAH-DNA, 6.2 versus 2.3/108; aromatic-DNA, 2.5 versus 1.4/108; P <0.01). HPRT Mf (a longer-lived marker) was somewhat less affected by the decline in exposure (13 versus 0.8, P < 0.05). Moreover, in the second year several long-term workers had low levels of adducts, but elevated HPRT Mf. Thus, PAH-DNA and HPRT Mf were highly correlated in the first year (n = 17; r = 0.67;P <0.01), but not in the second year or in the two years combined. However, when analysis was restricted to workers with detectable levels of adducts (who included the more highly exposed workers) the correlation was significant between PAH-DNA and HPRT (n = 17; r = 0.65; P = 0.005). In contrast, aromatic-DNA adducts and HPRT were not correlated in either year. These results suggest a molecular link between somatic gene mutation and PAHs; and they highlight the need in such molecular epidemiologic studies to consider the varying lifetimes of the individual markers.
Polycyclic aromatic hydrocarbon-DNA adducts in smokers and their relationship to micronutrient levels and the glutathione-s-transferase m1 genotypeGrinberg-funes, R. A., Singh, V. N., Perera, F. P., Bell, D. A., Young, T. L., Dickey, C., Wang, L. W., & Santella, R. M. (n.d.).
Page(s)2449-2454AbstractSixty-three male cigarette smokers were entered into a cross-sectional study to determine whether inverse associations existed between polycydlic aromatic hydrocarbon (PAH)-DNA adduct levels and intake/serum levels of vitamin A, vitamin C and vitamin E. Associations between PAH-DNA adducts and intakes of carotene, as well as serum levels of β-carotene, were also determined. Fasting blood samples were collected for assays of PAH-DNA adducts in circulating mononuclear cells, plasma cotinine and serum levels of vitamin A, β-carotene, vitamin C and vitamin E. Since genetic deficiency in the detoxifying enzyme glutathione S-traasferase M1 (GSTM1) has been associated with increased risk of lung cancer, GSTM1 genotype was also determined. Analysis of PAH-DNA adducts by competitive enzyme-linked immunosorbent assay (ELISA) indicated that 70% of the subjects had detectable adducts, with a mean of 4.38 adducts/108 nucleotides (range 1.00-24.1/108 Pearson's method was utilized to determine whether any associations existed between the various host variables and PAH-DNA adducts. Previously, no significant associations were found between PAH-DNA adducts and cigarettes smoked/day, pack-years, daily/life time tar exposures or plasma cotinine levels (Santella et al., Carcinogenesis, 13, 2041-2045, 1992). PAH-DNA adducts were inversely associated with serum cholesterol-adjusted vitamin E levels (r = -0.25, P ≤ 0.05) and with smoking-adjusted vitamin C serum levels (r = -0.22, ≤ 0.09). Stratification by GSTM1 genotype indicated that these associations were limited to subjects with the null genotype. The relationship between adducts and serum cholesterol-adjusted vitamin E was significant in those of the null genotype (r = -0.38, ≤ 0.04), but not in those with the gene present (r = -0.12, P = 0.5). Similarly, for smoking-adjusted vitamin C, the relationship with adducts was stronger in subjects with the null genotype (r = -035, P ≤.0.06) than in those with GSTM1 present (r = -0.05, P = 0.77). These results are consistent with findings of prior epidemiological studies Identifying significant inverse associations between anti-oxidant micronutrient status or GSTM1 genotype and the incidence of lung cancer. Additional studies should be conducted to confirm a possible role for vitamin E in PAH-DNA adduct formation and to explore further the possible roles of vitamin A, β-carotene and vitamin C in modulating adduct formation and lung cancer risk.
Hprt and glycophorin a mutations in foundry workers: Relationship to pah exposure and to pah-DNA adductsPerera, F. P., Tang, D. L., O’neill, J. P., Bigbee, W. L., Albertini, R. J., Santella, R., Ottman, R., Tsai, W. Y., Dickey, C., Mooney, L. A., Savela, K., & Hemminki, K. (n.d.).
Page(s)969-973AbstractMutations were evaluated in workers in an iron foundry with exposure to polycyclic aromatic hydrocarbons (PAHs), measured by personal and area monitoring, ranging from <5 to 60 ng/m3 of benzo[a]pyrene (B[a]P). Mutation at the hypoxanthine guanine phosphoribosyl transferase (HPRT) and glycophorin A (GPA) loci (measures of molecular effect in lymphocytes and erythrocytes respectively) were assessed to demonstrate their relationship to external exposure at lower levels than previously analyzed in foundry workers at this plant (<50-200 ng/m3). The relationship between mutations and PAH - DNA adducts measured by immunoassay (as a measure of the biologically effective dose) was also investigated. The markers were analyzed for dose-response and interindividual variability. Workers were classified into three exposure categories (low, medium and high). PAH-DNA adduct values for the low, medium and high exposure groups were 5.19, 6.10 and 9.57×10-8 nucleotides respectively (r = 0.28; P = 0.08). HPRT mutant frequencies (adjusted for age and cloning efficiency) for the low, medium and high exposure groups were 1.04, 1.13 and 1.82×10-6 cells respectively and demonstrated an upward trend with increasing exposure that was of borderline significance (r = 0.46, P = 0.06). In contrast, HPRT mutations were highly correlated with PAH-DNA adducts (r = 0.67; P = 0.004). Interindividual variability in mutant frequencies ranged from 1.5- to 4.5-fold within the three exposure categories. With respect to GPA variants, NN frequency (Vf) in erythrocytes (which reflects chromosomal loss and duplication, recombination or gene conversion) was not positively correlated with PAH exposure. The level of NØ Vf (arising from small-scale structural mutations in the GPA gene or from larger-scale chromosomal rearrangements or deletions) increased slightly, but not significantly, over the three exposure groups from 8.2 to 10.7 to 11.8/106 cells (P = 0.32). Interindividual variation in GPA NN Vf ranged from 2- to 18-fold and in GPA NØ from 4- to 5-fold. NN and NØ Vf were highly correlated (P = 0.001) but no correlation was seen between GPA and HPRT or between GPA and PAH-DNA adducts. Thus, the most interesting and novel finding is that, even at relatively low exposures to PAH, HPRT mutations were increased in parallel with PAH-DNA adducts. The observed association between PAH-DNA adducts and HPRT gene mutation in humans is consistent with experimental data for PAHs. These results support the use of both biomonitoring and personal ambient monitoring in further molecular epidemiology studies.
Molecular epidemiology of lung cancer and the modulation of markers of chronic carcinogen exposure by chemopreventive agentsPerera, F. P., Tang, D., Grinberg‐Funes, R. A., Blackwood, M. A., Dickey, C., Blaner, W., & Santella, R. M. (n.d.).
Journal titleJournal of Cellular Biochemistry
Page(s)119-128AbstractChronic inhalation exposure to environmental carcinogens such as polycyclic aromatic hydrocarbons (PAHs), cigarette smoke, 4‐aminobiphenyl (4‐ABP), ethylene oxide, and styrene is associated with elevations in biomarkers such as DNA adducts, protein adducts, sister chromatid exchanges (SCEs), chromosomal aberrations, gene mutation, and/or oncogene activation. These biomarkers indicate an increased cancer risk for the exposed population, although quantitative estimates cannot be made with certainty. There is convincing epidemiological evidence that the antioxidant and free radical‐scavenging vitamins C and E and β‐carotene (β‐C) protect against cancer of the lung and other epithelial tissues, with somewhat weaker evidence for retinol. Experimental studies demonstrate that these micronutrients are capable of blocking or reducing tumor formation caused by diverse carcinogens. A variety of mechanisms appear to be involved, including suppression of carcinogen activation, enhancement of carcinogen detoxification, induction of cellular differentiation, inhibition of mutagenesis, enhancement of immunologic function, and/or reduction of the formation of carcinogen–DNA adducts, SCEs, micronuclei, and other markers of genotoxic damage. Therefore, we have recently investigated the possible modifying effect of serum vitamins C and E, β‐C, and retinol on a number of such biomarkers in a case‐control study of lung cancer, and in a cross‐sectional study of heavy smokers. Preliminary results indicate an inhibitory effect of certain vitamins on DNA adduct formation. A significant number of human intervention trials are ongoing involving these vitamins. It appears that biomarkers can provide useful intermediate endpoints for assessment of both the mechanisms and the efficacy of chemopreventive agents.
Polycyclic Aromatic Hydrocarbon-DNA Adducts in White Blood Cells and Urinary 1-Hydroxypyrene in Foundry WorkersSantella, R. M., Tang, D. L., Young, T. L., Dickey, C., Whyatt, R., Perera, F. P., Paik, M., Ottman, R., Hemminki, K., Vodickova, L., Hemminki, K., & Savela, K. (n.d.).
Journal titleCancer Epidemiology Biomarkers and Prevention
Page(s)59-62AbstractIn an ongoing comprehensive evaluation of biological markers, workers in or near an iron foundry with varying exposure to polycyclic aromatic hydrocarbons (PAH) were analyzed for molecular response to this exposure. Exposure to benzo(a)pyrene, determined by personal monitors worn by the workers (2 to 60 ng/ m3), was considerably lower than in a previous study at this foundry (≤50 to 200 ng/m3) (F. P. Perera ef al., Cancer Res., 48: 2288–2291, 1988). Two biomarkers, 1-hydroxypyrene in urine measured by high-performance liquid chromatography with fluorescence detection (a measure of internal dose) and PAH-DNA adducts in WBC measured by immunoassay (a measure of biologically effective dose) were assessed to demonstrate their relationship to the lowest exposures yet analyzed in foundry workers. In addition, these markers were analyzed for dose response and interindividual variability. Cigarette smoking, but not age or charbroiled food, influenced the level of 1-hydroxypyrene but not PAH-DNA adducts. When workers were classified into three exposure categories (low, medium, and high), mean 1-hydroxypyrene levels were 2.7, 1.8, and 3.6 junol/mol creatinine, respectively. Comparisons by analysis of variance showed a significant difference between the groups after controlling for smoking (P = 0.02), but a trend test using multivariate linear regression analysis was not significant (r = 0.27; P = 0.07). Substantial interindividual variation was demonstrated by the 19-to 20-fold range in the values within each of the three exposure groups. PAH-DNA adducts showed an increasing trend, with exposure from 5.2 to 6.1 to 9.6 adducts/108 nucleotides in the low-, medium-, and high-exposure groups, respectively (P 0.08). The three exposure groups did not significantly differ from each other by analysis of variance (P 0.23). There was a 10- to 35-fold range in PAH-DNA adducts within exposure groups, reflecting the interindividual variability in this molecular response to PAH exposure. The correlation (r) between the two markers was 0.15 (P = 0.37). These results indicate that even at relatively low levels of benzo(a)pyrene (approximately 30-fold lower than in the previous study), we continue to observe a dose-response relationship between external exposure and the biologically effective dose of PAH.
Cigarette smoking related polycyclic aromatic hydrocarbon-DNA adducts in peripheral mononuclear cellsSantella, R. M., Grinberg-funes, R. A., Young, T. L., Dickey, C., Singh, V. N., Wang, L. W., & Perera, F. P. (n.d.).
Page(s)2041-2045AbstractStudies on cigarette smoking related polycyclic aromatic hydrocarbon-DNA adducts in blood have produced conflicting results. To determine whether a subset of specific white blood cells is a useful marker for monitoring exposure to cigarette smoke, blood was obtained from 63 heavy smokers and 27 non-smokers. Adduct levels were determined by competitive enzyme-linked immunosorbent assay with a polyclonal antiserum recognizing benzo[a]pyrene and structurally related diolepoxide-DNA adducts. Analysis of the lymphocyte plus monocyte fraction from smokers indicated 70% had detectable adducts with a mean of 4.38 ± 4.29 adducts/108 nucleotides, while in non-smokers the corresponding values were 22% and 1.35 ± 0.78/108 (P < 0.001). Plasma cotinine levels differed significantly in smokers (286 ± 90 μg/l) compared to non-smokers (4.4 ± 3.3 μg/l) (P < 0.001). However, cotinine was not correlated with self-reported smoking history in these heavy smokers. Nor were DNA adducts in smokers correlated with cigarettes per day, pack-years and plasma cotinine, indicating large interindividual variation in DNA adduct formation. These data demonstrate lymphocytes plus monocytes from smokers have elevated levels of polycyclic aromatic hydrocarbon diolepoxide-DNA adduct levels compared to non-smokers.
Molecular and genetic damage in humans from environmental pollution in Poland