|MadSci Network: Medicine|
To answer your question as to whether or not one would get arsenic into their system from a poisoned rat, there always exists a very small possibility for this situation to occur. However, one should always realize the actual likelihood for this occurring and just how little of the poison you would be exposed to. Let's look at it this way. A rat is quite a bit smaller than a human and the amount needed to kill a rat would be a bit less than to kill a human. But, please be aware that the initial amount in the poison should not be disregarded as dangerous to a human. Poisons are designed to be effective with just a few bites from the rodent. Most wild rodents only take a few bites from one source then move just as if they knew it could be poisoned. Therefore, most poisons are made potent enough for just those first few bites. Since there are many different types of poisons out there we are going to take the most typical form for our explanation - a solid or powder form. The form of the poison will have an impact on its transportation to a food source that we may use. Now the rat eats a few bites of the poison and ends up crawling into another food source. A lot now is going to depend what happens in the next few steps. Does the rat simply eat some of this food and leave to die somewhere else? Does it die in that food source? Does it defecate or go to the restroom in this food source? These questions help us figure out how much of that poison will be available to contaminate what we might eventually be exposed to. If the rat eats from food source and leaves, small traces of the poison could be left from amounts trapped in its fur coat that fall out into the food source, amounts transported on its paws, and anything the rat may have spit out. The biggest amount to contaminate the food source will be any amounts that have fallen out of its fur coat and/or come from its paws. This amount will be more concentrated than any amounts the rat may have spit out. If the rat dies in the food source, we are hoping to see the rat and disregard the food source. This would be the single most contaminating source of arsenic poisoning - using a food source with the dead rat in it. This would mean that all the poison the rat ate and came in contact with will now be in that food source. A very unlikely occurrence. Finally, If the rat defecated in the food source, very small trace amounts could have been filtered out by the animal's system (most of the poison will be retained in the rat's body) and passed out of the body. These amounts are significantly smaller than contamination from the poison being carried in the rat's fur coat and on its paws. Even with these consideration we next need to ask how much of the food source is there and how much are we going to use. If it is a small amount and we use all of it, then we can assume we will be exposed to the full amount the rat left in the food source. If this was a large bag of something, the small amount of poison will be diluted in the overall mass of the food source. Given these considerations, the most realistic concentration of arsenic we could be exposed to is if the rat should contaminate a small amount of food directly with the poison itself. This amount would be quite small and not be a significant health concern over the many other health issues associated with a rat getting into our food sources (diseases and other scary illnesses) or eating a poisoned rat directly.
With such a small quantity contaminating a food source in comparison to what the rat actually ate, the chances of a person getting sick from the poison are rare. I can not say that someone may be severely allergic and have a reaction to such small quantities of rat poison, it may happen. However, the realistic likelihood for this to occur would be very rare. In efforts to address the second part of your question on the health effects of arsenic, arsenic in low quantities may create nausea, vomiting, diarrhea, decreased red and white blood cells, slight abnormal heart rhythm, blood vessel damage. An acute, strong and short term exposure to arsenic may be characterized with the following health effects (not inclusive nor exclusive): skin contact can cause burning, itching, and a rash; breathing a liquid spray or powder form can cause nose and throat irritations; eye contact may cause red, watery eyes and irritation; high exposures can cause poor appetite, nausea, vomiting, and muscle cramps; heart effects with an abnormal EKG occur with high exposures. Long term low level exposures may cause ulcers or holes in the bone dividing the inner nose; nerve damage creating a "pins and needles," numbness, and weakness of the arms, hands, legs, and feet; liver damage by causing the blood vessels to contract, and significant decrease in red blood cell production. Another consideration given to long term exposures to arsenic is the increased chance for developing skin cancers. A typical indication of a possible overexposure to arsenic is the appearance of white lines on/in the fingernails and/or toenails. Clinical testing for arsenic poisoning include a urinalysis, blood testing (blood cell count), liver functionality testing, and a general physical exam of the nose, throat, skin, eyes, nails, and nervous system. It is ALWAYS best to seek out a physician if arsenic poisoning is suspected. I hope this has answered your questions.
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