Tuesday, March 22, 2005

Science Lesson

I was never really great at the hard sciences (especially biology), mostly because there’s too much to remember. Parts of the cell, organs, chemical names, rules for how they combine—it can get overwhelming very quickly.

But science’s growing complexity and fundamental role in economics (like genetic engineering) and politics (like the EPA) warrants everyone to learn some science terms to better sort through the issues. Here are two such words I found while reading Challenging Environmental Mythology, by Jack W. Dini.

The first is bioavailability, which describes the amount of a substance that’s available for interacting with other agents in the environment. Toxins might have a high bioavailability in the lab (thus making it very likely some amount will kill a given organism) while in nature that same amount of toxin could have a lower bioavailability for the same organism (thus making it less likely to kill it). Most evidence suggests that soil, for example, greatly lowers the bioavailability of chemicals.

The EPA doesn’t pay attention to bioavailability factors when it determines how harmful a substance is. The same goes for other studies done by scientists who are either ignorant of the phenomenon or have a vested interest in overestimating risk. It’s like citing experiments that drown people in water to conclude water is toxic. Bioavailability can vary dramatically (28.2% to 99% decline between six different soils) and diminishes with respect to DDT, DDE, DDD and dieldrin via earthworms.

The second term is chirality which describes the form of amino and nucleic acids. All such molecules can manifest as either “left-handed” or “right-handed,” even though they are comprised of the same atoms with the same quantities of each. Sometimes the “mirror image” is inactive. Other times, it can be dangerous. In 1957 thalidomide was used to lessen morning sickness, but its mirror image caused birth defects. Doses administered with both versions led to the false conclusion that the chemical itself was bad.

Mixed doses can be common (25% of all pesticides, for example, have mirror images), and the EPA doesn’t even acknowledge chirality as a factor. This is reflected in past environmental data which never distinguished which forms of the chemicals in question were present. A 1999 Nature report noted that traces of DDT derivatives, PCBs and plasticizers aren’t really as bad as once thought once you’ve adjusted for chirality.

I have to point out that if we didn’t politicized science and kept it in the private sector, these gaps wouldn’t be as bad because there’s a private sector incentive to recognize poor science and correct for it. Politics, however, isn’t about truth; it’s about perception. And that means never having to admit you were wrong.

3 comments:

Anonymous said...

Funny you should bring up thalidomide...

The problems seen with thalidomide were caused by irresponsible testing procedures on the part of the private organization responsible for manufacture and testing.

A pharmacologist working for the governmental organization, the FDA, was responsible for stalling the pharmaceutical company from marketing it in the US due to the gross incompetence shown in the drug's testing phase.

The German manufacturer of the drug (the name escapes me) continued to market and supply it in Australia, Asia, Europe, and Africa. What caused it to finally be removed from the market (after several thousand gross deformations) was political and media-related backlash.

Not science.

The manufacturer of the drug continued to deny and suppress information about the side effects of thalidomide for years.

Industry has no more stake in correct science than the government. There is no more incentive to pursue accurate science in one than the other. Profit, as any psychologist will tell you, is all about image.

Or perception, if you prefer.

Government or industry, nobody likes to admit being wrong.

Daniel Collins said...

To add to your scientific delving, one criticism of genetically engineered plants is that lateral gene transfer could occur, potentially compromising unsuspected speices and thus ecosystems. But what if the gene being transfered were not compatible in some way?

In all of life on Earth, proteins are left-handed and sugars are right-handed. This chirality matters. Now, if you created an organism that had right-handed proteins and left-handed sugars, a reverse chirality that would extend to the genes, then perhaps gene transfer would indeed not be compatible. Some people at MIT, and probably other places too, are thinking about this in the context of synthetic biology. [See: Wired 13.01: Life, Reinvented].

An interesting idea, until I remembered the case of thalidomide. We should probably be wary of eating proteins and sugars with the wrong chirality.

David said...

Anonymous,

Your interpreation is well recieved but there should be some things to be made aware of.

- Careful of hasty generalization. Just because preception made (temporary) profit here, doesn't mean it always makes profit.
- The name of the company is Grünenthal. No wonder you couldn't remember it. (I can't even pronounce it.)
- While the company did falsify documents (and they should be punished for that), independent tests approved the drug because at the time they didn't know enough about proper testing samples.
- The FDA rejected the drug because the newest reviewer (Frances Oldham Kelsey) happened to have experience in testing pregnancy drugs. The FDA worked because of coincidence and individualism, things that bureaucracies aren't known for depending on.
- There's no reason to believe if the FDA was replaced with private organizations it wouldn't have been caught. (Kelsey could have just as easily been working for a private company that tested drugs independently.) The difference is if the FDA makes a mistake, there's no indenpendent organization to catch it.
- No one said the market is perfect. As you can see, the FDA's actions were most based on chance, rather than inherent effiency and accountability.