small farm

The Road to Probably

small farmLast week, the International Agency for Research on Cancer (IARC) of the World Health Organization announced a summary of a soon-to-be published monograph about organophosphate insecticides and herbicides. An assessment of glyphosate, popularly known as the pesticide, RoundUp®, set the blogosphere on fire.

According to the summary, researchers concluded that glyphosate is “probably carcinogenic to humans.” The use of probably is not my own. That is a direct quote from the report.

The Road to Probably

How did the IARC come to this conclusion? These criteria stand out:

  • Limited evidence of carcinogenicity in humans for non-Hodgkin lymphoma
  • Sufficient evidence of carcinogenicity in experimental animals
  • Evidence of DNA and chromosomal damage in human cells

It’s worth noting as well that “. . . other explanations for the observations (called chance, bias, or confounding)
could not be ruled out.”

The reason is that the findings—for humans, anyway—are based on meta-analysis of observational studies of farm workers and individuals handling/dispensing pesticides. Unlike the lab animals, we don’t experiment with humans. No one is going to volunteer to be in the pesticide application group.

What we’re left with is a distinction between association and causation. Without randomized assignment and sampling of a populaton, science can only find associations, not causes. And that is what makes it problematic.

Confusing to the General Public

Based on the evidence and review, the language of the summary is correct. Science can’t declare something causal without an experiment to control for the confounding factors that may contribute to cancer risk.

Unfortunately, the correct verbiage opens itself to misinterpretation and confusion. Many of the articles I’ve seen reporting on the news have been careful to include the probably part. That’s good from the science perspective; but it’s bad for the general public. In our world, it either does or does not cause cancer. Probably isn’t good enough.

Another thing to bear in mind is the source of the evidence. The human evidence is based on farm worker exposure. The average Joe isn’t going to have the same contact with glyphosate as someone who uses it as part of his job. The other wildcard therefore is the amount of exposure.

As Paracelsus, the Father of Toxicology, reminds us,

“Only the dose makes the poison.”

And that’s where the research needs to go, as problematic as it may seem. In the meantime, it bears mentioning what a pesticide is. A pesticide is “a chemical preparation for destroying plant, fungal, or animal pests.” The findings of the IARC shouldn’t come as any surprise. Chris DR
photo credit: Central Iowa via photopin (license)

drought extreme weather

You Didn’t Build That Storm

drought extreme weatherWe’re in an age now where we want to cut to the chase and get to the facts. We don’t want the whole story; we want the Reader’s Digest version. We even want it with the most complex issues of our time, including climate change.

Extreme Weather and Climate Change

You’ve undoubtedly have read this talking point, but it bears mentioning again. Weather is what you see outside your window. Climate is the prevailing weather conditions for an area. They are not synonymous, though you won’t get that idea from popular media.

Instead, every single snowstorm, tornado, hurricane, and heavy rainfall is attributed to climate change. Both weather and climate are complex phenomenon. To pigeonhole a single event to anthropogenic climate change is too simplistic. Other things contribute to both, like oceans, volcanoes among other things.

What Science Says

Even science acknowledges this fact. The abstract from a 2013 paper from the Bulletin of American Meteorological Society states:

“Approximately half the analyses found some evidence that anthropogenically caused climate change was a contributing factor to the extreme event examined, though the effects of natural fluctuations of weather and climate on the evolution of many of the extreme events played key roles as well.”

The quote refers to 19 analyses of extreme weather events in 2012. As you can see, there is some disagreement with half finding some evidence and the half, not. And notice as well that the the paper references some evidence, not definitive. It also acknowledges other facts, including natural fluctuations.

I bring this up not to split hairs, but as a plea for truth in reporting. The real story is not being told. Instead, we have the snark as evidence by this headline from Bloomberg Businessweek: “It’s Global Warming, Stupid,” in a reference to Superstorm Sandy. I hate to break it you. You didn’t build that storm.

Fallacies Abound

Let’s consider the science. Climate scientists work with past data and modeling. They can’t create an experiment in the traditional way as in a double-blind, randomized controlled setting. As such, they can find correlations but not causation.

Second, in a twist on the chicken-and-the-egg storm, global warming brings about climate change. The unfortunate coining of the former term has fueled many skeptic arguments, sometimes with the ridiculous use of snowballs.

Third, let’s us not forget the Post hoc ergo propter hoc fallacy. (The phrase is Latin for “after this, therefore because of this.”) The argument goes like this: Climate change is happening. We had a huge storm, therefore it must be climate change.

This fallacy often shares the limelight with the appeal to ignorance or argumentum ad ignorantiam. In this case, the argument states that it must be climate change because you didn’t prove that it’s not. The fallacies show us what is wrong with this whole argument.

How About a Solution?

As I wrote last time, the thing missing in this whole dialogue about climate change is rational communication. That means no snark, no Weather Channel euphemisms for any weather event, a grasp of science and statistics, and no political ideologies confusing the issue.

Yes, I accept that climate change is occurring. Yes, there will be consequences. No, I don’t equate it to social issues or politicizing. I want the same things as you want: clean air, clean water, and a healthy environment. Can we all agree on that? Chris DR
photo credit: Dry Riverbed via photopin (license)