Monday, May 7, 2007

Everything is toxic.

This weekend I received an interesting e-mail from a reader, where he asked me why I wasn't worried that BT-corn contains a toxin in it. I wrote in my response to the reader:

Everything is toxic in the wrong dose. Water. Oxygen. So the question we ask isn’t “Is BT safe?” but “Is the dose of BT that you could conceivably get safe?”.
Understanding toxicity isn't just related to BT-corn and GM-food (and I don't want this blog to become all GM all the time). This is of importance to understand everything in your life from X-rays to homeopathic medicine to the environment. So let's do a bit of a toxicology primer (I'll write about long-term health studies in the future).

So what did I mean when I said water is toxic? Was I being facetious? Water can kill you? Well, yes. Recently, a woman killed herself drinking too much water in a water-drinking competition in California. A simplified version of why drinking too much water can kill you, is that you have very specific concentrations of salts (electrolytes) in your blood (and in all the cells of your body). Your body does a pretty good job of keeping those salts at the right concentration. But if you take in a large amount of water too quickly (and we're talking about gallons, here), you essentially dilute out the salt concentration in your blood, and you die. Over longer periods, you can piss out the extra water, to keep the salt concentration within the right range, but if you drink the water too quickly, it can kill you. This is the reason that when you get an IV in the hospital, they inject a dilute salt solution, and not pure water. A pure water IV pushed at a high enough speed would kill you (and even at low speed would likely hurt like shit - any medical folks care to comment?).

Really, everything is toxic. It's much more useful to give a figure of how toxic something is. To do this, we ask the question, how much of compound X (in this case, let's go with water) would it take to kill 50% of the animals that were treated with it. We refer to this figure as the lethal dose 50, or LD50. When looking at things that are not very toxic, we may fail to calculate an LD50, in which case we use the highest dose it is possible to give to an animal, and say that the LD50 is higher than that.

For water, the oral LD50 is greater than 90 mL/kg. In this particular case, it means that they failed to reach a dose of water that killed half their rats, and are calculating based on the highest dose that they were able to give to rats. That means, that if you give a rat 90 mL of water/kg of rat into their stomach, less than 50% of them will die. If you translate this into a human (where the numbers won't be exactly the same, but will be fairly similar), you can give a little over 6L of water to a 150 lb human before 50% of them will die (6 L is about 1.5 gallons). Or around 13.5 lbs of water. That's a lot of water.

Let's compare this to pure BT. Folks who have examined the toxicity of BT have found that when administered orally, that at levels of 10,000 mg/kg, it wasn't toxic. So to compare that to water, 90g of water/kg didn't produce toxicity levels of 50%, and 10g of BT/kg, didn't produce toxicity levels of 50%. Just the fact that folks are unable to get to doses high enough to kill 50% of the animals suggests that these are both fairly safe compounds. Note, I don't say safe, I say fairly safe. There is no absolutely safe compound.

Let's look at a few other compounds that are toxic enough that we can see an LD50. Table salt has an LD50 of 3000 mg/kg (note that smaller numbers mean the compound is inherently more toxic, as it takes a lower dose to kill the animal). So table salt is more toxic than pure BT. And what about the Gabriel Garcia Marquez's favorite poison of lover's, cyanide. It has an LD50 of 5 mg/kg (or the ultratoxic-terror-weapon: botulism toxin, with the incredible LD50 of 0.0000012 mg/kg).

Now back to where I started from, that BT is a toxin. The reason that BT has been engineered into plants is that it kills some types of insects. Meaning that while it is on the same level as water or table salt for toxicity to humans, it's much more toxic to insects. While we share many of the same sensitivities to toxins with rats and mice, we share fewer sensitivities with insects.

So the next time, someone tells you, "BT-corn is toxic!", you can tell them that you know, and that you're not afraid. Everything is toxic.

Digg!

5 comments:

the sacred_monkey said...

Please take a moment to consider this.

The LD50 numbers mentioned here are for when half the population is KILLED. NOT for when they are HARMED.

The question is whether or not a small amount of a substance is HARMFUL (also known as "TOXIC"), NOT whether or not it is so toxic that it will kill a person (or rat).

An amount slightly less than that which would KILL someone obviously would still cause serious HARM. Likewise, an amount much less than that which would kill a person should still be suspect as causing harm, but on a smaller scale.

It should not be assumed that decreasing the does of a substance transforms the chemical into something safe and good for you, while rather it may simply dilute the effects of it, causing SUBTLE damage, rather than ACUTE damage.

Subtle toxicity can accumulate over time, through repeated exposure and chemical buildup. For example drinking water with arsenic in it may cause no observable effect at first, but over time one could develop cancer or gangrene. Fluoride in the water is another example, which accumulates in the bones (JAMA, 1990, 1994; Robins, Ambrus, 1982) and the brain's pineal gland (Luke, 1997, 2001) and is proven to then cause fluorosis (Heller et al, 1997 and McDonagh et al, 2000) as well as indicative data that it lowers IQ (Muellenix, Denbesten, Schunior, Kernan, 1995). See fluoridealert.org for more on that.

The decision to view the risk of subtle or chronic toxicity as negligible and therefore safe is a JUDGEMENT CALL which should be made ON AN INDIVIDUAL BASIS.

Environmental pollutants, fluoridated water, mandated vaccinations or other medications, and Genetically Modified Organisms are all examples of potentially harmful substances being forced upon the people, thereby stripping them of their right to choose for themselves whether or not to trust in the safety of the substance.

If YOU want to ingest questionable chemicals that others view as toxins, then by all means feel free to take that risk with your own body. The problem is in forcing or deceiving others.

Supposedly 7 out of 10 products in a typical grocery store contain genetically modified ingredients which ARE NOT LABELED AS SUCH. Even if that statistic were to be inaccurate, it wouldn't change the argument so long as even a SINGLE GMO product is on the market without the knowledge and INFORMED CONSENT of the consumer.

GMOs are not only evident of causing adverse health effects (more evidence than I imagine you are aware of), but they involve a great deal of other problems as well. As previously mentioned, there is the violation of individual American rights with a lack of informed consent to consumption. There are also issues such as uncontrolled spread of GE plants and even GE ANIMALS which present a major threat to the world’s ecosystems. There are major issues involving the patenting of life which most people are unaware of. There are issues with corporate control over farmers and our food supply. There is evidence of an inferior growth profile of GMOs to natural organic plants. GMOs may result in antibiotic-resistant bacteria, and more.

I AM SINCERELY BEGGING YOU PLEASE TAKE THE TIME TO VIEW THE FOLLOWING:

* The Future of Food (Documentary film)
http://video.google.com/videoplay?docid=3764995188693165078
http://www.thefutureoffood.com

* The Health Dangers of Genetically Engineered Foods and their Cover-up, by Jeffrey M. Smith (Video interview)
http://www.consciousmedianetwork.com/video/112207.htm

* Say No To GMOs (Web site)
http://www.saynotogmos.org

sacred_monkey said...

A quick comment to further point out that there can be toxic effects below the LD50 level..

CCOHS (Canadian government): "Remember, the LD50 is only a ball park figure so that lethal toxicity can be compared. It says nothing about levels at which other acute toxic, but non-lethal, effects might occur."
Source: http://www.ccohs.ca/oshanswers/chemicals/ld50.html

Hazardous Substance Fact Sheet (US Government): "Long-term effects can occur from repeated exposures to a chemical at levels not high enough to make you immediately sick." Source: Hazardous Substance Fact Sheet, Sodium fluorosilicate, CAS No. 16893-85-9, http://nj.gov/health/eoh/rtkweb/documents/fs/1701.pdf

Anonymous said...

Insulin is harvested from genetically modified bacteria. So are most anti-biotics, better not use those either. Same for soy sauce. Would you consider selective breeding genetic modification? If so we've screwed up every animal we've cultivated since the beginning of time.

Anthony said...

I figured I should add one more thing to the argument about BT that seems to be passed over by the GMO-phobic.

BT-GMOs produce the precursor to an active BT molecule. The actual molecule that is being added to the corn is essentially harmless to humans and insects alike. What happens to that molecule once it's been ingested is of paramount importance.

In the insect gut (which we're taught is basic, rather than acidic like the human gut), the BT molecule is altered (cleaved) in a highly specific way by an enzyme in the insect gut to produce the active molecule. Only this specially processed fragment goes on to kill the insect.

In the human gut, the BT molecule is never cleaved in the same way (to produce a toxic molecule), and is either broken down into small fragments, denatured or allowed to pass "harmlessly" through the digestive system.

I have no problem with BT-GMO crops, although I am against the use of "round-up ready" crops for non-health related reasons. (eg, Ethical reasons - I do not approve of Monsanto or their tactics.) At least if you're going to take a stand for or against GMO crops, educate yourself on the biochemistry of what's going on. The links posted by the first commenter are more paranoid than educational.

Anonymous said...

March 27, 2009 2:24 PM Anonymous, I really like your style. You are absolutely The Factician are right on point. Let all the scared monkeys out there live their lives in fear. Just means when they die, they won't have lived nearly 1/2 as pleasant a life as us.