[shvcko99]

I know that many poisoning will come with obvious and noticeable symptoms.

How about if we accidentally eat or inhale very small amount of chemicals because we are not "extremely careful", for example, when someone cleans with spray disinfectant near you but he of course doesn't spray on your food directly but you know, those chemicals are usually gaseous or they are able to "fly" some distance, many of us probably eat it but we don't know it, we don't even have any noticeable symptoms. There are endless situations in life, it's just a very common example.

Does it mean we are fine? How does our body handle small amount of chemical when it enters our body? Will it be just excreted safely or stay and accumulate in our body permanently

[Borek]

First of all - everything you deal with is a "chemical". You drink water? Chemical. Carrot juice? Water with chemicals.  You eat an apple? Oh my, someone even prepared a list of chemicals present in an apple, it looked exactly as the list of ingredients in a Mars bar combined with water sanitizer, was just several times longer.

Second: it is dose that makes a poison. There are many substances ("chemicals" if you want) that are absolutely necessary for living but poisonous in excess. Heavy metal like zinc is an environmental hazard, yet you need traces in your body for a correct working of some of the enzymes, if memory serves me well same about manganese and copper. Excessive doses of vitamin D will make you sick and will probably kill you given time. And so on, and so on, and so on, these are obvious examples that I could list a vista, there is plenty of others. Your body deals with numerous poisons and pathogens all the time, it evolved to do so and is quite effective at keeping you alive and well despite all the risks.

Third: there is no "one size fits all" answer. All mechanisms you described can act, depending on the substance and its amount. Plus, many of the potentially harmful compounds are metabolized in the liver, which is actually why poisonings often end with liver damage.

[shvcko99]

First of all - everything you deal with is a "chemical". You drink water? Chemical. Carrot juice? Water with chemicals.  You eat an apple? Oh my, someone even prepared a list of chemicals present in an apple, it looked exactly as the list of ingredients in a Mars bar combined with water sanitizer, was just several times longer.

Second: it is dose that makes a poison. There are many substances ("chemicals" if you want) that are absolutely necessary for living but poisonous in excess. Heavy metal like zinc is an environmental hazard, yet you need traces in your body for a correct working of some of the enzymes, if memory serves me well same about manganese and copper. Excessive doses of vitamin D will make you sick and will probably kill you given time. And so on, and so on, and so on, these are obvious examples that I could list a vista, there is plenty of others. Your body deals with numerous poisons and pathogens all the time, it evolved to do so and is quite effective at keeping you alive and well despite all the risks.

Third: there is no "one size fits all" answer. All mechanisms you described can act, depending on the substance and its amount. Plus, many of the potentially harmful compounds are metabolized in the liver, which is actually why poisonings often end with liver damage.

Hi, well, you are right, I should modify my terms and question a little bit.

I wasn't aware that "Chemical" could mean anything. OK, I am concerned about any chemical that are not supposed to enter our body normally, but found in our surroundings every day that possibly, e.g. household cleaning agent, hair spray, dirt or debris or anything found in the air but not naturally existing like oxygen or carbon dioxide etc

Yes, I truly understand that poisoning depends on the substance and its amount. I am concerned about when the amount isn't enough to get poisoned or experience any noticeable symptoms that you will know immediately and seek for medical support, but the substance has actually entered your body in an insufficient amount for real, how they are handled? Are they mostly discharged through egestion and excretion safely?

[Borek]

but not naturally existing like oxygen or carbon dioxide etc

"Naturally existing" is just another meaningless classification. Practically all these substances exist in nature, and even if some don't they belong to classes of the compounds that are present in our environment. Our bodies did not evolve to deal with particular substances but with these classes and in most cases they do have mechanisms to deal with these things.

how they are handled? Are they mostly discharged through egestion and excretion safely?

As I already wrote: all mechanisms you described play their roles and all are in use, there is no single, simple answer.

[shvcko99]

but not naturally existing like oxygen or carbon dioxide etc

"Naturally existing" is just another meaningless classification. Practically all these substances exist in nature, and even if some don't they belong to classes of the compounds that are present in our environment. Our bodies did not evolve to deal with particular substances but with these classes and in most cases they do have mechanisms to deal with these things.

how they are handled? Are they mostly discharged through egestion and excretion safely?

As I already wrote: all mechanisms you described play their roles and all are in use, there is no single, simple answer.

I am not expecting one single answer that fits all but are you able to provide comments on my question based on general case? i.e. non-food substance, insufficient quantities to cause poisoning or symptoms

[shvcko99]

but not naturally existing like oxygen or carbon dioxide etc

"Naturally existing" is just another meaningless classification. Practically all these substances exist in nature, and even if some don't they belong to classes of the compounds that are present in our environment. Our bodies did not evolve to deal with particular substances but with these classes and in most cases they do have mechanisms to deal with these things.

how they are handled? Are they mostly discharged through egestion and excretion safely?

As I already wrote: all mechanisms you described play their roles and all are in use, there is no single, simple answer.

but if you still think my questions are too broad to answer, then I will try to give a clear note on the "substance" I am concerned. May I ask how bad it could be if our food is unintentionally contaminated with small amount of household cleaner, detergent, dead bugs, paper, newspaper, ink from newspaper, paint pieces, rubber, cigarette smoke, cigarette residue, saliva from unknown someone, mucus or booger from nose, etc

[Borek]

99.999% of the cases it is not a problem at all. Look around - how many of your friends/relatives got sick because of any of these?

Form the statistical point of view you are making much more harm to yourself stressing yourself with a fear that something can happen, than you risk from these things happening.

There was at least one, widely reported case of a woman hit by a meteorite, yet we don't bother to carry thick armor plates all the time, doesn't make much sense.

[Babcock_Hall]

You may want to read up on xenobiotics.  I might be tempted to define them as compounds that we ingest that are not food.  Sometimes are they are defined as being synthetic (man-made), but I don't see a good reason to do so.  Many xenobiotic compounds undergo metabolism of some sort.  They might be conjugated with (joined to) another molecule to make them more water-soluble, and therefore easier to excrete in the urine.  They might also undergo a transformation of some kind, usually involving the addition of one or more oxygen atoms.  This also makes them easier to excrete.  Drugs, whether man-made or naturally occurring, are a type of xenobiotic.

[shvcko99]

99.999% of the cases it is not a problem at all. Look around - how many of your friends/relatives got sick because of any of these?

Form the statistical point of view you are making much more harm to yourself stressing yourself with a fear that something can happen, than you risk from these things happening.

There was at least one, widely reported case of a woman hit by a meteorite, yet we don't bother to carry thick armor plates all the time, doesn't make much sense.

I agree with you most of the time.

However, just a line sharing about my experience. For all kinds of reasons my food was once contaminated with all the substances I have mentioned above. Sometimes I threw the precious food away, sometimes I ate it but felt unhappy, if you were me, I think you would also feel bad to have food contaminated with all those things. I just want to learn about this issue more scientifically so that my worries can go away faster next time. Thanks for your comment I am more comfortable now