John Riddell learns about some dangerous chemicals
From the TV3 News website:
| CHIPS COULD CAUSE CANCER | UPDATED: 05:56PM WEDNESDAY 26 JUNE |
The World Health Organisation has begun a three-day emergency meeting in Geneva to evaluate the danger of some popular foods. They’re concerned about a recent discovery that certain starchy foods, from deep fried chips to potato chips and bread, contain a chemical called acrylamide. It can cause cancer in rats, but there is no evidence it does the same in people.
There are lots of chemicals in food. Even organic food. Are the chemicals in our food dangerous? Is food safe?
For example many foods contain a chemical called cellulose. How much do we really know about cellulose?
If I want to know if cellulose is dangerous I need to design an experiment. Experimental design can be tricky.
I have limited resources. The best thing to do would be to look at a large sample of individuals. See what happens when they are exposed to small amounts of cellulose over a long period of time. Unfortunately I don’t have the resources to study this way. So I choose to use a high dose of cellulose over a short time period.
I get a rat and put it in a cage. I place the cage about five metres from the base of a 25 metre tall tree. Using a chainsaw, I chop down the tree so that it falls on to the cage containing the rat.
Then I have to repeat the experiment a few times to make sure the first result wasn’t a fluke.
Every single time I have carried out this experiment the rat has died. The conclusion is obvious. Cellulose is dangerous.
Next I must publish the results of this experiment in a “peer reviewed journal”.
This is in the unlikely event I have made a mistake somewhere. If there is something wrong with my experiment, hopefully someone will spot it.
Somebody did. They raised the point that it might not have been the cellulose that killed the rat. Trees also contain other chemicals such as lignin or even water. Maybe it was one of the other chemicals?
Good point. I have to consider the criticism and design a new experiment to answer this question.
Since a tree is mostly water I design another experiment to test if it could have been the water that killed the rat. I put a new rat, in a cage, into 100 litres of water.
And the rat dies.
So I conclude that water is harmful to rats. But this does not necessarily mean that cellulose is not also harmful.
After all, I noticed that while the tree killed the rat instantly, the water took a few minutes. Perhaps there was something in the combination of cellulose and water that made the tree more harmful than merely water alone.
But before I look at the synergistic effects I want to extrapolate these data to look at how dangerous small doses of water might be.
If 100 litres of water causes death in three minutes this suggests 50 litres would cause death in six minutes. Continuing this extrapolation shows that even a small amount of water will significantly reduce the rat’s life expectancy.
Also, what are the implications for humans?
Anecdotal evidence suggests that many humans who have been in large amounts of water have also died. As yet I haven’t yet been able to obtain funding to test this myself. However if water really is dangerous, can we risk even the smallest exposure?
Okay, some scientists have raised doubts about the validity of high dose trials. Just because a high dose of a chemical is harmful, they say this doesn’t necessarily mean that smaller doses are also harmful. And just because it is harmful to rats doesn’t necessarily mean it is harmful to humans.
But can we afford to take the risk? Do we really know the dangers? The results so far are inconclusive. Obviously more research is needed. I just need a bit more funding. However there is one conclusion we can draw.
Scientists don’t like rats, but I suspect the feeling is mutual.
No rats were harmed in the preparation of this article.
