I RATE YESTERDAY'S WEBINAR AS OVERALL IMPRESSIVE

Last evening's Webinar on Risk Assessments was worthwhile as I and TAG members learned about some of the inputs, intents, calculations (formulas) and more that make up proper Risk Assessments. At the end we were reminded of the intense necessity to have an accurate Conceptual Site Model (CSM) and an accurate Conceptual Exposure Model(CEM). Without either one the entire Risk Assessment is called into question (i.e. doomed/a sham/ etc.) We were also advised that Risk Assessment's need to be defensible in order to have any credibility.

We were again focused on the CSM, followed by the Risk Paradigm, and then the Protection Goals, the Framework and finally the Toxicity of Chemicals. The Risk Paradigm is simply three overlapping circles of Contaminants, Receptors and Exposure Pathways. Where the three circles overlap is the Risk involved by the Contaminants following the Exposure Pathway and affecting the Receptors. The Protection Goals vary dramatically between Human and Ecological Risk Assessments. With human beings it's all about protecting the most vulnerable such as the elderly, children, pregnant women and mothers etc. With Ecological Risk Assessments it's about protecting the populations of wildlife not the indiviual members. With invertebrates and plants it's about protecting communities not populations or individuals. The one exception is listed species at risk which receive greater protections. The Toxicity of Chemicals basically discussed the difference between Threshold and non-Threshold chemicals. The dose is the poison for many chemicals but nor for carcinogenic, mutagenic chemicals etc. Non-Threshold chemicals literally can cause adverse affects at any concentration or dose.

I was impressed to learn that many of the numbers plugged into the various equations are provided by Health Canada. In other words all the various parameters in the various equations are not the purvue of the polluter and his consultants. Certain things like the amounts of soil ingested by children, the fraction of time receptors are exposed, bioavailability of specific chemicals and time outdoors that children are exposed to dust are pre-determined by Health Canada hence limiting fudging of those numbers.

Of huge interest to me was the insistence of the importance of practical and useful Method Detection Limits. This was emphasized, especially the fact that the lowest detection limits possible are required and that they MUST BE BELOW THE STANDARDS AND CRITERIA provided by the provinces or the federal government. Certainly the TAG Chair and members all picked up on that and recalled the ridiculously high detection limits used in the Canagagigue Creek study by GHD which were dozens to hundreds of times higher than various criteria.

Finally it was also made clear that human exposure is predicted not measured. In other words tissue samples are not collected from potential human receptors to see if indeed they have accumulated the contaminants of concern on a particular site. While this is a weakness compared to Ecological Risk Assessments that collect tissue samples and have formal Tissue Residue Guidelines, clearly this is neither practical, acceptable nor ethical with humans.

This was a very enlightening Webinar and I'm glad I attended.