The Researcher's Perspective
Podcast Interview with Dr. Frederica Perera

Views and opinions expressed in these podcasts are those of the interview
subjects and do not necessarily reflect the views, opinions, or policies
of EHP or of the National Institute of Environmental Health Sciences.

Narrator: EHP presents The Researcher's Perspective.

Ernie Hood: Welcome once again to The Researcher's Perspective, the podcast series from Environmental Health Perspectives, the monthly journal published by the National Institute of Environmental Health Sciences, one of the National Institutes of Health. I'm your host, science writer Ernie Hood.

On this episode of The Researcher's Perspective, we welcome Dr. Frederica Perera to the program.  Dr. Perera is Director of the Columbia Center for Children's Environmental Health at the Mailman School of Public Health, at Columbia University in New York.  

In August 2008, EHP published a commentary article from Dr. Perera entitled Children Are Likely to Suffer Most from Our Fossil Fuel Addiction.  That paper will be the topic of our discussion today.

Dr. Perera, welcome to The Researcher's Perspective...

Dr. Perera: Thank you very much.

Ernie Hood: In your August 2008 commentary in EHP, you make a compelling case that young children and developing fetuses are most vulnerable to the adverse effects of both exposures to the toxic byproducts of fossil fuel combustion and to global warming caused by the world's continuing use of fossil fuels.  
It's easy to see why toxic exposures would be so directly harmful, but how might global warming also harm children in particular?

Dr. Perera: Global warming, we think, is going to be harmful particularly to children.  The average temperature of the earth is predicted to rise by as much as 2-4 degrees Celsius, and that kind of temperature increase could bring more heat waves, flooding, famine, and forced migration, along with the trauma and all those psychosocial effects.  Children are more at risk, biologically, of heat stroke, certainly of drowning, of malnutrition, diarrhea, allergies, and infectious disease, which is also predicted to increase as the result of global warming.  And children are also more susceptible to psychological trauma.  And the reasons they are more susceptible are biologic-the systems, organs, are rapidly developing and therefore more prone to insult.  The immune system and other defense mechanisms are not mature as they are in adults, so that puts children, the very young (and I should include the fetus as well) at heightened risk.  Also, children are very vulnerable to psychological trauma.  All of these effects could be manifest not only in early childhood, but throughout the life course, because we now know that when there are insults that are sustained early on in life, those can have effects later on, as with cardiovascular disease and cancer.  There are a number of examples of other diseases as well, where the damage sustained even as early as in utero can play out later on in heightened risk of those chronic diseases.  So for all those reasons we think of children as being more susceptible

Ernie Hood: Dr. Perera, your article linked both the toxicity of fossil fuel burning emissions and the adverse effects of global warming with the unique vulnerability of the very young...do you see the possibility of an interactive effect at work in terms of impact on children's health?

Dr. Perera: Yes, there are a number of examples of that.  I think one-there are two, actually, good ones...are the fact that with higher temperatures the formation of ozone from volatile organic chemicals is accelerated.  That is, volatile organic chemicals and nitrogen dioxide.  That formation is more rapid at higher temperatures, and also the production of allergens, that is, pollen and other allergens from plants is more rapid as well with increased heat, in a warmer climate.  So those are two ways that you can have interaction.  

I'd like to go back, though, to the issue of susceptibility of the fetus and young child to point out that we actually have, from our various studies internationally we have evidence of greater vulnerability to one of the primary pollutants that comes out of fossil fuel burning in addition to carbon dioxide, CO2-polycyclic aromatic hydrocarbons.  In these cohort studies that we have been carrying out, we've compared the level of genetic damage from these chemicals (we abbreviate polycyclic aromatic hydrocarbons to PAHs), and we have measured the adducts formed when these chemicals are breathed in by the pregnant mother and then are transferred across the placenta to fetus, where they can be activated and bind to DNA.  And we measure that biomarker, we call it, that fingerprint, in umbilical cord blood DNA, white blood cell DNA.  And we've compared the level of damage to DNA from these PAH chemicals in the mother, taking a small sample of her blood at delivery and in the umbilical cord white blood cells, and that even though we know from many studies that the placenta is protecting the baby to a certain extent and reducing the exposure by about a factor of ten, despite that reduction of exposure to the fetus, the levels of DNA damage are equivalent in the newborn cord blood and in the mother.  And that is indicating that the fetus is on the order of about ten-fold more sensitive to genetic damage from these chemicals.
  
Another manifestation of vulnerability could be more damage to what we call the epigenome, that is, not direct genetic damage but damage to the epigenetic or methylation programming of genes, such that they are abnormally expressed, or silenced during critical developmental periods.  And we have found recently that these same chemicals, PAHs, do alter methylation patterns as we're measuring them, again, in the umbilical cord white blood cell DNA.  There are many reasons why that could be potentially serious in terms of chronic disease later on in the children, and we are looking at that in our prospective studies.  
So, two aspects of vulnerability, or two ways in which this vulnerability might be expressed in greater DNA damage as well as greater disruption of what we call epigenetic programming so critical to early development, and here too we know, as I mentioned before, that insults acquired early, in utero and early in childhood could be playing out over the entire life course in the form of various chronic diseases.  

Ernie Hood:  Dr. Perera, your description of that early vulnerability and susceptibility is quite telling, and now we see that the science behind our knowledge of the links between early exposures and long-term adverse health effects has really advanced quite significantly in recent years. Where do you see the research in that area headed at this point? 

Well, you're actually right that it has advanced, and actually I'll pause for just a moment if it's OK and mention that a grip on what the effects of exposure during the in utero period could be on children, and we at Columbia have looked, as well as other investigators, have focused on the in utero window of susceptibility, and we've followed children, we've measured exposures during that time, using biomarkers as well as personal monitoring of the pregnant mother, and then we followed the children forward.  And we have found that the exposures prenatally to these PAHs that I mentioned, which are primary fossil fuel pollutants, toxic pollutants, that they are associated with reduced fetal growth, with more developed mental problems at age three, with reduction in cognitive function at age five, and also in evidence of greater asthma risk in children.  In other words, they're not just a trigger for asthma, but they appear to be an early cause or contributing factor to asthma in children.  
So, you're right that we have been able to really flesh out our understanding of the risks of these exposures, and I think where the field is heading now is to draw the causal links very firmly by getting a better understanding, through the use of biologic markers or biomarkers like the ones I've described in order to fully document, or as best we can, document the mechanisms by which these pollutants are causing disease, and by which they might interact with other pollutants, and also interact with susceptibility factors.  So those susceptibility factors that we and others are studying are genetic factors, nutritional, and also psychosocial factors.
  
And I wanted to bring this back to what we were talking about earlier about global warming, if I can try to pull this all together somehow...
My commentary set out to do something that I felt was needed, which was to link two areas of research and two areas of concern together, and to bring those together seeing through the lens of concern about the health of children.  Because in the past, studies have focused on the toxic pollutants like PAH, or nitrogen oxides, or lead or mercury, or benzene from fossil fuel use, and then other studies have focused on the risk from climate change, not so much focusing on children, but some have touched on that area.  But nobody had tried to pull it together, to think in terms of the cumulative risks, the interactive risks, and also the fact that if you turn things around in your mind, you can consider these risks and these health costs as benefits of taking action to reduce fossil fuel combustion and the exposures that emanate from it.  So that was the goal of this commentary, to put it all together in one place, and then to point out that by protecting children we're doing wonderful things for them, not just in childhood but also over their life course.  We're also protecting future generations, because there is the concern about transgenerational effects of these exposures, and so we can think about this as a way of looking at the benefits of taking action, and I wanted to end the article with pointing to some very authoritative reports on the fact that the technologies and the methods to significantly reduce greenhouse gas emissions, and our reliance on fossil fuel, and our toxic exposures from fossil fuel, are at hand now.  And that was the conclusion in 2007 of the Intergovernmental Panel on Climate Change, who said that stabilizing of global warming can be achieved at relatively low cost, using known technologies and practices currently available.  That was in 2007.  
So I think for all of these reasons there is, and I'm glad to see now, there is movement in this direction in a way we haven't seen in the past years, also, in terms of the political will and muscle behind it to take some action, and I think our children and their children will thank us very much.  

Ernie Hood: Dr. Perera, you conclude the commentary with a call to action, stating that the needed solutions already exist to move away from fossil fuel use...and that implementing them is economically viable compared to the long-term costs of doing little or nothing.  Do you see any signs that we are moving in that direction, towards less reliance on fossil fuels and towards mitigation of global warming?

Dr. Perera:  Yes I do, and I think there are some very positive signs, and not only signs and talk, but action, and I'm so happy to see that, because it's been a long time coming.  But we actually, now we have an administration and world leaders and also people who are able to put into effect these new technologies, and who see both the ecological health advantage and also the financial opportunities here.  I see the will to take the actions toward reducing our reliance on fossil fuel and moving to cleaner or renewable alternatives.  That makes me very happy to see, because I know that the benefits will be tremendous to our children and to future generations.  I really am very positive that we will see some really wonderful improvement and change with benefits accruing across generations.  

Ernie Hood: Dr. Frederica Perera, thank you so much for joining us on this edition of The Researcher's Perspective.

Dr. Perera: You're very welcome, it was a pleasure.  

Ernie Hood: And thank you for listening to this edition of The Researcher's Perspective, the EHP podcast.  Join us again next time as we explore another unique perspective in the environmental health sciences!