 |
 |
Gerry, I think the real answer here is to treat every form of toxicity testing with caution. I can however vouch for Toxmaping of sites using lux biosensor techniques. I had one undertaken on a site where existing chemical analysis (repeated - many,many times) had provided information on toxicity. The chemical analysis (undertaken by one of the UK's largest and most reputable environmental consultants) took over 18 months to get the consultants to tell us what the problems were and what was required to be done (well nearly - they wanted to do further testing!!). I arranged for the site to be checked by a firm using lux biosensor techniques by sampling from the same bore holes. They were given no prior information on the site, yet were able (within 10 days) to provide the same analysis as the Chemical Counters . In fact they identified a hot-spot that had been missed by chemical analysis - Why? - because the chemical counters didn't expect the contaminant source to be there. Therefore they didn't look for it. In addition the biosensor analysis told us that a large volume of the contaminated soil could be bioremediated, and how long that would take. This saved my client over £700,000. The chemical counters wanted to did and dump the lot - not very environmentally friendly and certainly not in the best interests of the client. Importantly both the local authority and the environment agency bought into biosensor analysis. I will be delighted if everyone continues to question the benefits of biological indicators - that means that I and my clients can continue to benefit from the competitive edge provided. I am not a scientist but I would have thought that using a biological tool to identify a biological risk would make sense. As a property professional working in the contaminated land sector I can say that I have found the availability of rapid toxicity testing of sites to be a great advantage. The provision of a Toxmap in 2D and 3D form is invaluable to developer clients and legislators alike. It is saving my clients money as it saves the endless reiterative searching previously conducted using chemical testing. At least you can target detailed assessment on areas where toxicity exists instead of the trial and error techniques used by traditional analysis - biosensor techniques only look for toxicity. Simple and very effective. If anyone has any doubts you should try it - no point critising if you haven't experienced it first hand. I can pass you contact details of the firm I use if you are interested. I continue to use Toxmaping through the use of this firm on all Phase 2 investigations I am involved in - they are rapid (usually get results back with Toxmap within 14 days - once done in 3 days!!), reliable (every case has been fully advocated through the local authorities) and relevant (clients and legislators can understand the output). And on top of all that they are significantly more cost effective. They also rapidly provide a Remediation Map of the site identifying where bioremediation would be effective, thus reducing the volumes being dumped and saving vast amounts of cash (don't shout about this one though as this does give my clients a huge competitive advantage) I can only speak from practical experience - I hope the doubters can do the same. Regards, Eric Shearer, MRICS, Director in Charge Chesterton Brownfield Regeneration Group [log in to unmask] tele - 01224 644272 -----Original Message----- From: Contaminated Land Regime Discussion List [mailto:[log in to unmask]]On Behalf Of Dr. Paul H. McMahon Sent: 05 September 2002 11:45 To: [log in to unmask] Subject: Bio-availability & risk assessment (still) Will, I too would recommend caution when using biological indicators as a guage of soil toxicity. Dr Jason Weeks of WRc - NSF in Marlow gave a paper in london last week, titled "Current & emerging Ecotoxicological tests for contaminated land", where he touched on topics such as earthworm bioassays, bio & lux biosensors being used to provide site toxicity maps. At the end of the paper, I specifically asked the question "so can we use ecotox tests (i.e the bioluminescene tests) to give an indication on human health risks?" As far as i understood from the reply from both Paul Nathaniel and Jason, to try to make the leap of faith from concentrations of contaminants which affect eco receptors to concentrations to concentrations of contaminats that can affect human health will place you on decidedly shakey ground. (pardon the pun) As far as I understand, it is propably innappropriate to try and extrapolate the results of what is effectively an ecotoxicity map to human health. All that been said, the concept of the ecotox map allowing the investigator to target areas for further intrusive investigations seems reasonable. I have to caveat this reply by saying that this is only my understanding, and please dont take this as Paul's or Jason's position. It is my interpretation of the reply to my question, but anyone, please come back and comment. Gerry McGarrity ______________________________________________ Gerry McGarrity Contaminated Land Officer Environmental & Consumer Protection Department Dundee City Council 8 City Square Dundee DD1 3BG Tel 01382 43 4038 Fax 01382 43 4080 mob 0789 987 3995