Dr. Bruce Ames, an American biochemist, is the inventor of the Ames Test. It is test or biological assay for the mutagenicity of chemical compounds.
A positive test indicates that the compound is likely mutagenic and as mutations are often linked to cancer, it has often been used as a test to determine the carcinogenic potential of chemical compounds.
Unfortunately, like most diagnostic tests, there are occasional false-positives and false-negatives. In other words, it is not perfect. But it is a lot cheaper, quicker, and easier than animal trials on rats and mice which have higher levels of false-positives and false-negatives.
In this context, it is not surprising that what Dr. Ames has to say about chemical carcinogens and cancer carries a fair amount of weight.
Recently, I came across a paper written by Dr. Ames and Dr. Lois Gold with the title: "Paracelsus to parascience: the environmental cancer distraction" (Mutation Research, 447, p. 3 - 13). The central thesis is that we need to challenge some of the existing paradigms regarding what causes cancer if we are going to proceed into the 21st century as an informed society.
Specifically, the authors have chosen four topics to focus on as the underlying ideas are implausible and lacking in evidence, from their point of view.
The first is tied to a saying attributed to Paracelsus: "Only the dose makes the poison". This is a central tenet for many researchers studying toxicology.
For example, everyone knows that arsenic is poisonous but that is not, in fact, correct. Some of the compounds of arsenic are poisonous. Others are not. Arsenic is an element and it is only when it is combined with specific other elements, such as oxygen, in a particular fashion, such as an oxide, that the compound becomes a poison.
Is Arsenic poisonous? No. Is oxygen poisonous? No. But put them together in the right way and you have a very effective poison. This is a distinction that often gets missed in any discussion of chemical compounds and particularly in discussions of carcinogenic compounds.
Further, small doses of some poisons have no effect. The body disposes of the chemicals quite easily or can convert them to harmless forms. It is only when a massive dose is received that disease or death ensues.
Arsenic fits into that category. Lobster contains arsenic as part of its biochemical make-up and yet you don't see people keeling over after sitting down to surf-and-turf. Note that the arsenic is in the lobster as part of its metabolism. It is impossible to eat lobster without getting a small, harmless dose of arsenic.
In this case, the dose means that it is not a poison.
In discussing carcinogens, Drs. Ames and Gold make the point that "Half of all chemicals, whether natural or synthetic, are positive in high-dose rodent cancer tests. These results are unlikely to be relevant at the low doses of human exposure."
The further point out that the dichotomy that exists in the public media between "synthetic" and "natural" is false. They point out that: "Human exposure to naturally occurring rodent carcinogens is ubiquitous, and dwarfs the general public's exposure to synthetic rodent carcinogens."
That is to say the number of natural carcinogens that each person encounters every day is significantly greater than the number of synthetic carcinogens.
Using pesticides as a proxy, the average American or Canadian ingests somewhere between 5000 and 10000 different natural pesticides in their normal diet. Estimates put this at about 1500 milligrams of natural pesticides per person per day.
The same analysis shows that on average, we are only consuming 0.9 milligrams of synthetic pesticides per person per day. The push back on this is that synthetic compounds are more potent carcinogens or mutagens and therefore more dangerous. It would be a good argument if it was true but it is not.
The list of naturally occurring compounds in food is extensive and ranges from benzaldehyde to methylhydrazine. The foods that this compounds are found in range from spices to fruits to vegetables to the ubiquitous tomatoes and potatoes. You can't avoid eating naturally occurring pesticides and being exposed to naturally occurring carcinogens.
Nor would you want to as missing out on micronutrients, such as folic acid or iron, is directly linked to many forms of cancer.
Why did Drs. Ames and Gold bring this issue up? The point that they are trying to make is that: "Putting huge amounts of money into miniscule hypothetical risks damages public health by diverting resources and distracting the public from major risks."
Or put another way, we are not necessarily spending our efforts in the wisest way. Working to ensure that everyone has access to fundamental nutrition might be a better use of our resources if we want a healthy population.
It is an argument worth considering.
