Looking at my web stats, I see that this site has been visited no fewer than 29 times in the last few days under the search term "chris snowdon dose makes the poison". Why someone should so persistently associate this phrase with me, I can't say, but for that Googler, I hope the following helps:-
The dose makes the poison is a fundamental principle of toxicology. It is generally attributed to the 16th century scientist Paralcelsus, who said:
"All things are poison and nothing is without poison, only the dose permits something not to be poisonous."
In other words, everything is toxic and everything is harmless. It is the quantity that makes the difference. It is this basic piece of scientific understanding that makes the last Surgeon General's claim that "there is no safe level of secondhand smoke" so risible. It is also one reason why scientists scoff at the homeopathic claim that remedies become more potent as they become more diluted. And it's one reason why the term 'toxic chemicals' can be misleading. When we talk about toxic waste, everyone knows what we mean. Saying that a product contains 'toxic chemicals' implies that these chemicals are dangerous at the levels found in the product. Sometimes, however, the reality is that they could be toxic at higher quantities or under experimental conditions. That's true, but it would be true of oxygen and vitamin C too.
Ignoring the principle that the dose makes the poison makes it possible to claim that acrylamide in french fries, or "gender-bending" phthalates in shower curtains, or nitrosamines in smoker's carpets can cause cancer. It's junk. All these things can be harmful, but not at the levels found in real-world situations. (If you really need to know why these claims are junk, click here, here and here).
I hope that helps whoever was searching. I only wish I could assist the people who found the site by Googling "weasel in wales", "politicians that like fruit cakes" and "fisting with pipes". Alas, you will need to go elsewhere for that kind of information.