Today I am going to share a document that was created by the Center for Health, Environment and Justice.  I have been holding on to it for a few days and do not remember how I came to find it.  It may have been a link in a news story.
   The handout was prepared for parents.  The issue it addresses is chemicals in products that children use for school.  The message and the handout are important for all people - of any age.
   Understanding that we have more hazardous, toxic, and carcinogenic chemicals in our environment (land, water, air, products) than we can count and classify, protecting ourselves from them is a concern.  Those that we have identified as having a harmful effect at any level, such as lead, are regulated and products that contain it (lead paint, leaded gasoline) are banned.   We also have substances that are harmful but a certain amount can be found in the human body before any health risk occurs.  Think of methylmercury found in fish.  It is measured in parts per million and we can eat a certain fish many times because it is low level (tilapia = .013PPM) or just a few times, if ever, because it is high (tuna, swordfish = .99PPM).  The mercury released from coal fired power plants is the main source of fish contamination.  The EPA could impose regulations (as mandated in the Clean Air and Clean Skies Acts) on those power plants but is stymied by the tremendous push back and power from the energy industry.
    Sometimes the amount of exposure to a chemical doesn't matter as much because the likelihood of that exposure is so rare.  This was once the idea with radiation from medical imaging.  The radiation amounts were moderately high in CT scans, but hardly anyone got them and if they did, maybe it would be one in a lifetime.  That has changed and efforts are being made to lower the dose and limit the frequency.  Remember the many posts on this issue and ask your doctor why you need the scans.  
  Within a similar context, consider the chemicals that are leaching out of our plastics. BPA, phthalates, polyvinyl chloride.... It is not that these chemicals are high in any one place but that they are in EVERYTHING -  EVERYWHERE.  This means we are under constant exposure.  If a substance is toxic, any level is too high if you are being exposed to it repeatedly every day.  So read this handout and consider the environment and your health a little more seriously.  In fact, it makes the banning of certain chemicals for use in plastics make a lot more sense.
 Here is the handout.
   And since so many of us want more info on fats in food, we can think of artificial trans fats as another of those toxic substances.   If you have something with 4 grams of trans fat on one holiday a year - than a dose of 4 grams is a safe dose.  If you have something with 4 grams of trans fat every day - you are substantially increasing your odds of a heart incident (stroke, infarction, death)  In that way, the dose is too high.  A dose of less than .5 grams a day is still a risk.  Less than 1 gram a month is a better level.