Archive for February 6th, 2008

Drinking water – or bathing in it – can be deadly (not) – part 2

February 6, 2008

Part 2:

The men in grey suits… are actually on the case

As discussed in my last post, the Altmed scare about “cancer-causing chlorination byproducts” in your tap water contains by implication the idea that The Man (the Govt, the regulators, the public health people, the water industry, take your pick) don’t care about you, and cynically ignore the risks, and play dice with your health.

This is, of course, a specific example of a key thread in the modern revival of Quack Healthcare: a deep mistrust of institutions in general, and “the Gubmint” in particular.

We have already seen in the last post how the information about chlorination by-products being a theoretical risk is actually not “a dark and dirty secret”. In fact discussion of the issue appears on numerous websites dealing with water quality, e.g. among many others here, here, and here.

Sterilizing tap water: a no-brainer

Most of this discussion understandably centres round the cost-benefit analysis of “sterilize tap water” versus “not sterilize tap water”. Even in an age where we in the developed world have a century’s experience with water sterilization, and take clean drinking water utterly for granted, we still get occasional waterborne disease outbreaks: for instance with Cryptosporidium. There have also been nasty E.Coli outbreaks in North America within the last decade when water sterilization broke down. And remember the panic in the flooding last Summer when clean water was not available?

If you want to know what the doctors think, then recall that when the British Medical Journal asked its readers a couple of years back to vote on what they thought was the most important medical milestone since 1840 (when the BMJ was first published) the clear winner was “the sanitary revolution“ – i.e. the introduction of clean water piped to your home (which basically means chlorinated water) and sewage disposal

Given this, to most public health people and drinking water system engineers water chlorination is a complete and utter no-brainer. It is a real risk (waterborne disease, which can be nasty and even fatal, and will usually present as an outbreak and possibly even an epidemic) against an essentially hypothetical one (infinitesimal increased risk of particular kinds of cancer from chlorination by-products).

And – surprise surprise – the suits are all over those chlorination by-products

However, even the more specific question of “Is there really a measurable increased cancer risk from chlorination by-products in tap water” has been considered, at length, by a high-powered independent committee in the UK. Strange but true. Furthermore, anyone with internet access can read exactly what they said.

So, contrary to what the Alties would prefer you to believe for sales purposes, our much-derided Ministries are actually on the case here. The committee concerned deliberates on cancer risks from chemicals in the environment. They have considered the toxicological and epidemiological studies on chlorination by-products that I have been reading, and indeed that Dr John Briffa has mentioned on his blog. However, their conclusion is not the same as his.

Overall, the… epidemiological studies fail to provide persuasive evidence of a consistent relationship between chlorinated drinking-water and cancer….

It remains possible that there may be an association between chlorinated drinking water and cancer which is obscured by problems such as the difficulty of obtaining an adequate estimate of exposure to chlorination by-products, misclassification of source of drinking water (including the use of bottled water), failure to take adequate account of confounding factors (such as smoking status), and errors arising from non-participation of subjects.

We therefore consider that efforts to minimise exposure to chlorination by-products remain appropriate, providing that they do not compromise the efficiency of disinfection of drinking-water.”

You can read the whole thing here:

This is a typical scientists’ conclusion: scrupulous, nuanced, and with a common-sense recommendation. The studies shouldn’t make you think tap water is bad for you, but it would be sensible as a precaution to use as little chlorination as is consistent with having safe (i.e. not full of bugs), drinkable, tap water.

The committee, called the
Committee on Carcinogenicity of Chemicals in Food, Consumer Products and the Environment”, or COC for short – is mainly composed of scientists. You can see the membership here. It is an impressive roll-call and they are sufficiently “authoritative” that I have even heard of several of them, though this is not my scientific field.

Again, contrary to what the Alties would typically have you believe (“Conspiracy!”), said Committee it is not full of food industry, or chemical industry, or water industry people. The members are academic scientists and doctors. They also declare their “interests” here, and very few of them even have any research funding from industries like “Big Pharma”. Mainly the list shows that some of them ended up with shares in Building Societies, and things like British Gas, that went private.

I have a lot of respect for the University scientists who sit on these kind of Government committees. It is not an easy job, or a “no real work” one, because there will be a lot of paperwork to plough through and master, which clearly takes time. Because they are doing it in connection with a responsibility for making recommendations connected to public health, they will be reading the stuff very carefully. They will also have three meetings in
London to attend a year, plus oversight of reports. All in all, a lot of work when it is something you do for no money, other than expenses. So they do it, I suspect, out of that old fashioned thing – a sense of public duty.

What impresses me is that this kind of mechanism shows that potentially toxic things in the environment are under constant scrutiny and oversight. Water chlorination and any potential hazards were first considered in detail in 1986, and again in 1992, and again in 1999. The reports are re-examined when there is any substantial new body of evidence, and the conclusions re-tested or altered. Which is proper science. A further review is probably likely some time soon.


The choice is yours

So – it is up to you. You can take your advice on the safety of British tap water from Dr John Briffa, or from the COC.

Dr John Briffa has a medical degree but has no experience of medical research, either in cancer causation, toxicology or epidemiology. He makes his living promoting “natural health”.

The COC is headed by a Professor of Carcinogenesis (the causation of cancer) who works for the cancer charity Cancer Research UK –hardly an organisation that would want more people getting the disease – and is stacked with Professors of Chemistry, Toxicology and Pathology, none of whom are earning a penny from the conclusions they reach.

I know who I am more inclined to believe. But hey, maybe that’s just me.