[rius]

Note: My english isnt well.
Everyone knows toothpaste's has chemicals in variety. Floride is the main chemical. But how do you know if its not harm your health in the future?
May be it cause cancer in the future. So what precautions do you take when you brush your teeths?
How long have you brush your teeths?
Are you take mouthwash while you doing this?
Does toothpaste chemicals harm to human body?

[Arkcon]

Well, what have you heard that makes you suspect that toothpaste ingredients may cause cancer?  Where have you heard it, and how did the speaker back up their claim?  These are worthwhile questions for a scientist to ask, and its good for everyone to ask questions along these lines whenever faced with a question like this.

[rius]

On Ebay:

http://www.ebay.co.uk/gds/The-5-Harmful-Ingredients-in-Toothpaste-READ-THIS-/10000000003239604/g.html

So; How do we know which chemicals are harmful or not?

[Corribus]

There are so many things wrong with the article you linked to, I wouldn't know where to begin.

In general you should be wary any time the point of an article is to get you to buy something, especially when it's snake oil.

[Furanone]

There are so many things wrong with the article you linked to, I wouldn't know where to begin.

In general you should be wary any time the point of an article is to get you to buy something, especially when it's snake oil.

I could not have said it better!

[rius]

There are so many things wrong with the article you linked to, I wouldn't know where to begin.

In general you should be wary any time the point of an article is to get you to buy something, especially when it's snake oil.

oh! maybe you are right but I read a similar article in a turkish news site about this. Despite those articles I have already interested in chemical substances harms.
Could you please tell me which bond, molecule or elements may cause to carcinogen. How do we determine : "Yes, this chemical is carcinogen?"

[kriggy]

Well its difficult qustion. There are many different carcinogens. From elements like cadmium or berylium (not all forms) through inorganic compounds like those of chromium (VI) to simple organic compounds like benzene or more complicated like Benzo[a]pyrene.
So even thought there are some common features, there are lot of carcinogens with very different properties.

The carcinogenity of a compound is usualy determined by some laboratory tests. As far as I know you just add the compound you are testing to cell culture and observe what happens. There are probably some more rigorous methods but this one is only one I know.
I hope I helped at least a little bit to answer your qustions.

and btw I wouldnt trust the article. Not only for the reasons Corribus said but also they just missinterpret data if I can say. Argumenting that fluorine in toothpase is harmful because it also part of nerve gas compounds is at least wrong argument. While it is true that organophosphates serve as very deadly nerve agents and they contain fluorine it is very different form that the one in toothpaste. Saying that "Sodium fluride is same as sarine" is exactly same argument as "kitchen salt is very dangerous because it contains chlorine and chlorine is very toxic gas"

[Bidagdha_TADIR]

You will brush and then spit out the toothpaste materials, so chemicals are not of great issue. Not all toothpaste contain fluorides, nor does they need it. If not ingested fluorides are of no danger and they will make the teeth resistant to dental carries. The main ingredient of a toothpaste is abrasives such as calcium carbonate which is also available as medicine. Preservatives are the one everybody is so cautious of nowadays but those are present in medicine like syrup as well.

So, you are okay. Even if you ingest it, the damage is usually not of great concern. Since you won't eat it, no need to worry about the harmful chemicals.