A recent article by Girouard and Zagury (doi:10.1016/j.scitotenv.2008.12.019) on the available of arsenic bound in soil highlights a recurring theme in soil environmental toxicology. Our current measurement techniques for contaminants in soil may be significantly underestimating the risk associated with a polluted soil to small children. Typically, we recommend that soils be sieved to pass a 2 mm sieve, or in other words, only particles less than 2 mm are analyzed. Sometimes we suggest that soils should be sieved to pass a 0.25 mm sieve. The reason we do this is that we know that concentrations of pollutants increase as we sieve to smaller and smaller sizes. However, what we don’t know is how ‘available’ pollutants in these smaller size classes would be to small children, or in other words, how easily can pollutants in small sized particles enter our bloodstream. The work by Girouard and Zagury indicates that the answer to this question is: more easily. Thus, the smaller the particles the more risk is posed to small children who might accidentally eat these soils. (as an aside, I’m sure you are wondering how much soil a children will eat. We estimate around 100 mg per day but in some cases, children can eat up to 13 g). As a society we need to revist how we assess risk from contaminated soils and ask the question: are we being protective enough?