Air cleanliness and food toxicity may be topics that many people feel powerless to control, but epidemiologists and biostatisticians are using their environmental health research to influence policies that lead to big changes. Kiros Berhane, PhD, USC professor of preventive medicine and director of USC’s Master of Science and PhD programs in biostatistics and epidemiology, has dedicated much of his career to developing statistical methods to determine environmental health outcomes, and is working on ways to measure relationships between environmental factors and respiratory health in children.
What is your research focused on?
My primary research focus is on the development of new statistical methods for public health research with specific focus on applications to environmental epidemiology. I am currently working on several topics (quantile regression, multiple outcomes, flexible modeling techniques, latent variable modeling – to name a few) with applications to health effects of environmental factors on respiratory health, obesity and tobacco related outcomes. One current area of focus has been the effects of multiple environmental factors on multiple health outcomes such as childhood obesity and new onset of asthma.
What are your goals in applying these statistical methods?
Our goal with this new application is multi-fold. First, we are working to apply these techniques to address a new problem dealing with the interrelationships between childhood obesity and asthma incidence. The new approach allows us to see if there is directionality in this relationship. Second, we would like to continue new methods by expanding this work to handle multiple interrelated environmental exposures.
What inspired you to get involved in statistics and epidemiology?
The problem of synthesizing effects across several interrelated health outcomes has been of interest to me for many years. This problem was identified as an area that needs methods development as part of our work within the Southern California Children’s Health Study. CHS is a long-running longitudinal study on approximately 12,000 children regarding the impact of environmental and genetic factors on children’s health. We specifically wanted to allow for inference across several lung function measures and asthma incidence outcomes to help determine the underlying respiratory health status of any given child. The methods development involved allowing for complex growth trajectories during childhood, misclassification in asthma diagnosis data and complex dependencies across outcomes. Over several years, we were able to develop new methods that would allow us to handle all these complexities. Now, we are trying to use these techniques within a new research initiative of our Environmental Influences on Child Health Outcomes grant to address the interplay between childhood obesity and asthma incidence by dealing with them jointly.
How collaborative is environmental epidemiology?
This work is a perfect example of how coordinated efforts between biostatisticians, epidemiologists and exposure scientists leads to better science for all involved – it is biostatistics at its best. It is a good example of the longstanding collaboration between the divisions of biostatistics and environmental health within our department. It is also a perfect example of using ongoing research platforms to train the next generation of scientists. For example, this work has been an outgrowth of a PhD dissertation by USC alum Yue Zhang, PhD, who is currently faculty at University of Utah.
What sort of impact has your research had?
I have been working on several aspects of this study for over 15 years. The research output has been great both from methodological and substantive points of view. Our work has informed regulatory decisions by local governments, the California Air Resources Board, the United States Environmental Protection Agency and international regulatory agencies. Several from our team have served on important review and advisory panels at local, state, national and international levels as a direct result of our work on this topic. Recently, we have shown that the improvement in air quality has led to improvement in respiratory health in children — potentially due to regulatory policies informed by our research. Hence, we can honestly say that the effect of our work has been very positive.
What does the future of environmental health research look like?
The health effects of long term exposures to air pollution were not well established prior to the work by CHS. CHS has been instrumental in making ground breaking progress on this topic and still remains one of the most comprehensive ongoing studies in the world. CHS has since branched out to several other health areas such as childhood obesity, cardiovascular health indicators, metabolic outcomes and tobacco related outcomes (especially with new products such as e-cigarettes). It has made significant contribution to our understanding of genetic determinants of children’s health and how genetics and environment interact in affecting children’s health. Hence, the research work is likely to continue on several fronts.
Why is environmental epidemiology so important?
There is emerging evidence that complex environmental mixtures are important determinants of cardio-metabolic outcomes. The possibility of collecting huge amounts of real-time data opens new opportunities for addressing complex public health problems. It also poses many new challenges as techniques need to be developed to handle the huge volume of data in a responsible way. Hence, biostatistical methods research and the multi-disciplinary research model that we have been following for many years remain crucial. If we did not continue this work, we would not have the capacity to properly handle the promising big data opportunities.
Who should be concerned about environmental epidemiology?
What can the public do to get involved?
Interested in biostatistics and epidemiology? The MS and MPH programs at USC offer concentration options that will provide you with the skills and knowledge you need to make a difference. Download our Degrees and Careers Guide to read more about our degree offerings and the field of public health.
— Carolyn Barnes