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That’s my concern as well Ruth I think a lot of authorities accept the 450 as there isn’t a better published figure Using the tdis and mdi I posted before I got a combined screening vale of 33mg/kg which is quiet attainable in both the districts I deal with (I'll post the full input paramaters I used next week when im back at North West Leicestershire) Just changing the tox to match that used by Atkins in their atrisk soil suite I got 377mg/kg combined out which is pretty close to the atrisksoil value so my other parameters cant be to far out from theirs (they only make the tdi and mdi values available as part of the suite) The tdi used in the atrisk soil suite is stated in the 2010 JECFA report to be linked to atleast a 3 point IQ drop in children under 4. Most IQ tests are +/- 3 points so is that significant??? Is 0.5 point iq drop linked to the 0.3µg/kg-bw/day minimal risk?? I know if someone told me my daughter could be subject to a 3 point IQ loss I would find that (Personal Opinion here) significant (assuming DQRA and more specific exposure parameters) Thanks Gareth Rees Mgeol (HONS) FGS Contaminated Land Officer E mail: [log in to unmask] Mobile: 07976 431 236 Contact Centre: 01858 82 82 82 Fax: 01858 82 10 00 DX DX 27317 Market Harborough Please Note I only work for Harborough District Council on Thursdays Fridays and alternate Wednesdays -----Original Message----- From: Contaminated Land Management Discussion List [mailto:[log in to unmask]] On Behalf Of Willcox, Ruth Sent: 19 February 2014 12:34 To: [log in to unmask] Subject: Re: calculating lead screening level using JECFA 2010 findings We do not accept use of the old SGV, particularly where the land use scenario involves use/access by children under 4 years old. This is due to increasing evidence that a very small increase in blood lead level can lead to significant adverse impact on neurological development. Questions we have had to consider previously: How much lead is in a child's fist of soil? What would be the resultant increase in blood lead level if this were ingested by a young child? Ruth Ruth Willcox Environmental Protection Officer Environmental Services Plymouth City Council Civic Centre Plymouth PL1 2AA T +441752304154 E [log in to unmask] www.plymouth.gov.uk -----Original Message----- From: Contaminated Land Management Discussion List [mailto:[log in to unmask]] On Behalf Of Chris Dainton Sent: 19 February 2014 12:19 To: [log in to unmask] Subject: Re: calculating lead screening level using JECFA 2010 findings Hello Gareth As no one else wants to reply openly! Firstly, don't go down this route in the real world - it ends in QRA madness (and that's not from the lead). But it's good to do the calcs. The soil ingestion pathway alone (at TDI of 0.3 ug/kg-bw/day) will give a 'GAC' of 20 mg/kg (by contrast Oral TDI via Tox -6 gives 243 mg/kg for soil ingestion alone using same MDI). If you ignore oral MDI, then soil ingestion pathway becomes 40 mg/kg (50% rule is invoked for the 20 mg/kg 'GAC' effectively making the TDI 0.15 ug/kg-bw/day!). The MDI also makes a mockery of the 0.3 ug/kg-bw/day TDI as background oral intake by BW for average female AC1-6 is 2.3 ug/kg-bw/day (average BW is 13.3 kg). For plant uptake you could adopt default 5/0.5/0.5/0.5/0.5 factors and let the model sort it. At kd = 3,000 the veg consumption pathway alone would give 508 mg/kg (Dutch RIVM kd = 36,000 would give pathway output of c. 6,100 mg/kg) Dermal indoors comes in at 41 mg/kg using default approach (the oral and dermal indoors pathways (both using Oral TDI) essentially drive the 'GAC') All the pathways conspire (taking into account MDI) to give a lead 'GAC' of 13 mg/kg (by my quick calcs...). Ignoring all MDI gives an upper bound of 26 mg/kg (50% rule invoked at 13 mg/kg) The best you'll get using CLEA (at the moment, C4SL approach aside) and the TDI of 0.3 ug/kg-bw/day will be between 20 and 40 mg/kg as you are rate limited by the soil ingestion pathway (soil ingestion rate) and the adopted MDI. Most other CLEA approaches I've seen/tried come in the range of 180 to 300 mg/kg. And given the BGS Urban NBC is 810 mg/kg..... And most LA seem to be happy to accept the old SGV of 450 mg/kg as a reasonable compromise. PLEASE DON'T QUOTE OR USE THESE CLEA OUTPUTS - THEY ARE QUICK ROUGH CALCS JUST FOR ILLUSTRATION! Kind regards Chris Dainton Peak Environmental Solutions Limited www.peakenvironmentalsolutions.com uk.linkedin.com/in/chrisdainton ******************************************************************************************************************************************** IMPORTANT: This e-mail (including any attachments to it) is strictly confidential and intended solely for the person or organisation to whom it is addressed. It may contain privileged, confidential or sensitive information. If you are not the intended recipient, you must not copy or distribute it to any other person or take any action in reliance. If you have received it in error, please notify your system manager and the sender as soon as possible and then delete it from your system. You can contact the Council through the website www.harborough.gov.uk, via email [log in to unmask] or by telephone on 01858 828282. 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