Wednesday, June 29, 2005

*On Water Safety and Chemicals in general*

This is somewhat related to Her post on the flourination of water and in particular the matter in which the anti-flourination camp has overblown the entire issue based upon some very fundamental misunderstandings on the nature of causality and in particular, the pharmaco creedo:"The dosage makes the medicine and the poison"

What happened is that in last month's issue of Lifestyle, a guy by the name of Richard Seah posted a pretty scaremongering piece on article on the dangers of Singapore's "world class water" due to the chemicals within it. Anyway, Lifestyle printed a retraction story in this month's article apologising for unthinkingly scaring their readers. Presumably, someone at PUB read the article and printed a firm rebutal letter. It's just a little sad that the editors actually let it get published without actually sending it for factchecking or even running it past real experts.

What is interesting is that I ran a google search on his name and I came across two articles which seem to be mildly contradictory in nature. One article about how MSG and aspartame might be tasty but bad for health which is pretty standard in its lists of criticisms. Here's the FDA's position. The seaweed he offers as a substitute is legitimate BUT what it does is to creates a false dicotomy between 'natural' and 'unnatural' chemicals/compounds (see below for elaboration).

The other talking about how the media wrongly took a study on the effects of Stevia (a sweetener) on mice and simply applied it to humans, something which he calls a case of newspaper misreporting. Why this article is significant is because it appears that he understands that studies on animals does not cross translate into humans (often you need toxicity test on 2 different species, if it's toxic to both, there's a good chance it's bad for us).

And I seriously doubt it's three different people.

Anyway, this month's Lifestyle article does a very competent job in debunking the prior article so I really won't dwell too much on it (it would have rated higher if it were longer and took pains to explain certain aspects which I mention below). But I would really like to emphasize the idea set forward above i.e. the dosage makes the poison. The American Council on Health and Science has a terrific publication titled "Good Stories, Bad Science: A Guide for Journalists to the Health Claims of "Consumer Activist" Groups" which does a fantastic job in answering basic questions on the basic premise on which these people work and why these assumptions are wrong. Do read the full PDF file, very enlightening.

Anyway our chemical fears are fuelled by a great number of scientific and factual errors that have allowed pseudo-science and such single issue pressure groups to gain too much credence.

1. 'Natural' is better than 'unnatural'. Chemicals are chemicals, that's how our body recognises and processes them. Sorry, but our liver does not differentiate between 'natural' and 'man-made' ascorbic acid (Vitamin C). More than that, ricin is one of the most toxic substances in the word and it's natural. So is poison ivy and nightshade. Plants do contain 90% natural pesticides by weight it being a natural defence mechanism and all, so synthetic pesticides are often a minor issue (given current safety levels). And we can parlay this into another rebutal to a innuendo commonly used i.e. that such chemicals don't exist in nature and is therefore dangerous. I mean it's entirely irrelevant as long as tests show that they are safe and besides they make up a small fraction of our contact with them.

2. There is no treshold or safe levels of 'toxic' substances. Seriously now, anything at high enough levels can be toxic, even Vitamin C (even if it's water soluble), at high enough doses and concentrations you can cause an overloading of the locality and hence cancer. Any drug at high enough doses can kill you, panadol included (although at MUCH MUCH higher levels than commonly expected. 10 tablets are not likely to even cause you any harm actually).

But the problem is that very often these groups extrapolate backwards and claim that even at low levels these things will kill you. Just for a though experiment, let's take very toxic substances. Is there a 'safe' level for lead or mercury or even arsenic? The answer is yes. What happens is this, your regulatory bodies (like WHO, FDA and their European equivalent) set limit values which achieve an "adequate margin of safety to reduce to a minimum any hazard to health in all groups of consumers" (UN speak).

1. So test are first done on groups of animals (so animal rights groups be damned) to set a limit called No Observed Adverse Effect Level (NOAEL)

2. Which is then further reduced to set one for humans called the ADI (Acceptable Daily Intake).

3. And then this is further reduced to make allowances for possible differences in animal and human biology

4. And then again further reduced to allow for differences in population (children and the elderly).

In the end, the ADI is anything from 100 to 10,000 times lower than the NOAEL. And the margin is actually greater because we are bigger than animals (which is why the nerve agents in insecticides don't affect us) and also because there likely is a level whereby there's absolutely no harm to us at all (or possible not granted).

At the end of the day, if you're worried about your health, work out more, eat everything in moderation and really stop worrying about such chemicals and 'poisons'. The stress is more likely to do you more harm than they will.



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