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How our foods and fuels drive poor air quality in the tropics

Friday, October 23rd, 2009


Palm oil has garnered a lot of news recently.  It’s an ingredient in many processed foods and, increasingly, is being used to make biodiesel fuel.

One initial concern was the destruction of tropical rainforests and peatlands to create palm oil plantations.  To the extent that these plantations are leading to habitat destruction in places like Indonesia, this threatens species like the orangutan.

In this week’s  early edition of the Proceedings of the National Academy of Sciences (open access), a team addressed a second potential problem:  air pollution, specifically ground-level ozone production.

The news about ozone is potentially confusing, so let me start with a quick primer:

  • Ozone’s chemical formula is O3, which is similar to oxygen we breathe in the air (O2).
  • Ozone is a highly oxidizing molecule, which means that it is harmful to living organisms when it comes in contact with them (such as when we inhale it).  If you have ever been around electrical motors and you smell a pungent odor, that’s ozone.
  • Ozone in the stratosphere (upper atmosphere) is good for life on Earth.  It absorbs ultraviolet light and prevents us from getting skin cancer.   This is the ozone that gets damaged by CFCs and other gases, creating the ozone hole over Antarctica.  Because we do not come into contact with this ozone, we benefit from it’s sunscreen properties without suffering any ill health effects.
  • Ozone in the troposphere (the part of the atmosphere near the ground, so it’s also called “ground-level” ozone), however, is not a good thing to have around because this is the part of the atmosphere that comes in contact with living organisms.
  • Ground-level ozone is often a byproduct of urban sprawl.  It forms when volatile organic carbon (VOC) from vehicles (think gasoline vapor) and vegetation (think the smell of Christmas trees) react with nitric oxides from car exhaust under warm, sunny conditions.
  • It’s a part of the chemical soup we call smog.  This is why we often see code orange or code red days in metro suburban areas like Washington DC, suburban NY, Atlanta, and Raleigh-Durham, NC warning people with respiratory illnesses, children, and the elderly to stay inside.
  • Although there is reason to believe that increasing ozone is connected with the rising incidence of asthma, that link has not been well established.
  • The World Health Organization has recommended exposure limits of no more than 50 parts per billion in any 8 hour period.

The PNAS article indicates that ozone production is a growing threat in palm plantations, which show higher temperatures and levels of VOCs and nitric oxides than adjacent rainforests.

Although the level of ozone in palm plantations is not yet at a level that threatens health, the team used a model of ozone production to suggest that if nitric oxide emissions were to reach levels seen in the developed Western world (which may be expected with further development and auto use), this could lead to ozone concentrations exceeding 100 ppb, which is considered an emergency air quality event.

Bottom line:  In tropical regions, we need to think of how to balance economic development, biofuel production, habitat protection, and–now– human health.   To the extent that processed foods and biofuel production are driven largely by consumption in industrialized countries, we share in the responsibility of dealing with this issue.

Already, some companies like Whole Foods have banned unsustainably produced palm oil to combat habitat destruction, but this doesn’t solve the new issue of air pollution.  The article suggests that new varieties of palm plants that emit much lower amounts of VOCs could solve this problem.  That’s good news.

Photo credit: / CC BY 2.0

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Posted in biofuels, pollutants | 1 Comment »

Do our daily routines put our health at risk?

Wednesday, October 14th, 2009

Every day, we are exposed to synthetic chemicals and radiation from consumer products.   If you asked me how risky these products are, my responses might range from “I don’t know” to “I don’t want to know” to “If they’re on the market, let’s hope they’re safe!”  Unfortunately, it’s difficult to know if many of the things we use every day really are safe.

Risk analysis is a four-step process by which scientists determine whether chemicals or other agents are unhealthy:

  • Step 1: Hazard screening–Does a chemical look or act like other chemicals already known to be harmful or safe?
  • Step 2: Exposure characterization–How much are we exposed to and how much accumulates in our bodies?
  • Step 3: Effects characterization–How do different doses of an agent lead to different health effects, or what we commonly refer to as “dose-response curves”? This is usually achieved using short-term lab animal tests or epidemiological data that show things like health effects of people working at industry sites or living in contaminated neighborhoods.
  • Step 4: Risk characterization–Given that we identify a chemical as being potentially dangerous (Step 1), and can measure our exposure (Step 2) and the effects that this specific exposure has on health (Step 3), what is the likelihood or risk that we will experience ill health as a result of the exposure?

As the EPA will tell you, there is often poor understanding of the long term risks of synthetic chemicals and radiation.  Much of this comes from the fact that

  • We have not screened many of the chemicals on the market for potential safety.  Here’s a quote from the EPA’s website in 1996, which was subsequently removed:

For the majority of the approximately 3,000 high production volume industrial chemicals produced in the United States in 1996, we have little or no publicly available hazard screening data. These chemicals, non-polymers produced in quantities of more than one million pounds per year, are found in the workplace and in thousands of consumer products. Even fewer data are available for the remainder of the some 70,000 chemicals on the EPA’s inventory.

  • Rigorous effects characterizations are hard to do.  Lab animal tests (rats, mice, etc.) are useful, but they are not a perfect substitute for understanding human health impacts.  Moreover, the kinds of long-term data we need rarely exist because that’s the nature of short grant funding cycles.  We know very little about the synergistic effects of multiple chemicals interacting in our bodies.  Finally, health problems analyzed in epidemiological studies can often be confounded with other lifestyle issues, such as weight, diet, exercise, and smoking.

Thus, we know we are exposed to these things, and we can even measure them in our bodies and in infants,  but we don’t know very well how this translates to long term health risk.

To some, this uncertainty might be license to ignore the issue.  To others, it necessitates better education about what’s in or emanating from our products so that we can decide for ourselves whether or not to limit exposure.

The Environmental Working Group has compiled several interesting lists of consumer products including specific ingredients that have the potential to be harmful:

So go ahead and check out your favorite vegetable, shampoo, cell phone, or toothpaste, and see what comes up.

photo credit: / CC BY-NC-ND 2.0

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Posted in environmental science, pollutants, risk analysis, shopping guides, toxics | 4 Comments »

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