This is not unexpected. I have run GACs for BaP using CLEA UK. The
percentage of average daily exposure (ADE) for the inhalation vapour
pathways is <1.4E-4 % for residential with plant, <3.2E-4 % for
residential without plant, <7E-7 % for allotments and <4.8E-5 % for
commercial land uses.
For your information, the significant ADE contributions are:
Res with - 55% soil ingestion, 25% veg consumption, 13% soil contact;
Res without - 75% soil ingestion, 19% soil contact;
Allot - 62% soil ingestion, 29% veg consumption; and
Comm - 79% soil ingestion, 11% contact with indoor dust, 11% soil
contact.
This indicates that in the worst standard land use (residential without
plant uptake) the contribution to the daily exposure is just less than
20%.
Regards,
Kevin Privett.
Dr Kevin Privett
Principal Geo-Environmental Consultant
Hydrock Consultants Ltd
Over Court Barns
Over Lane
Almondsbury
Bristol
BS32 4DF
Tel: (01454) 619533
Fax: (01454) 614125
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Cell phone: (07799) 430870
Offices in Bristol, Plymouth, Northampton, Stoke-on-Trent.
www.hydrock.com
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-----Original Message-----
From: Contaminated Land Management Discussion List
[mailto:[log in to unmask]] On Behalf Of Chris
Eccles
Sent: 09 February 2006 14:16
To: [log in to unmask]
Subject: Re: Benzo(a)pyrene
Has anyone else measured BaP vapour concentrations in the ground rather
than relying on overly conservative risk assessment model predictions?
We have a site with mean BaP of 21 mg/kg in a granular made ground. We
set up a large (25T capacity) test chambers to isolate the material from
outside interferences. At this site we found BaP concentrations in the
ambient air (about 3 ng/m3) to be higher than those found in our test
chambers. A sample with a much lower mean BaP of 5 mg/kg had a measured
air concentration of less than the detection limit of 0.5 ng/m3
(relative to a EH40 EAL of 0.25 ng/mg). This indicates that where
volatilisation is assessed to be the main pathway, modelled SSTL's are
highly conservative - at least in this case. We also found similar
results with other PAH's.
Chris Eccles
Director
TerraConsult Ltd
Bold Business Centre
Bold Lane
Sutton
ST HELENS
WA9 4TX United Kingdom
Tel: +44 (0) 1925 291111
Mobile: +44 (0) 7739 684421
Fax: +44 (0) 1925 291191
E-mail: [log in to unmask]
Web: www.terraconsult.co.uk
-----Original Message-----
From: adamc czarnecki [mailto:[log in to unmask]]
Sent: 09 February 2006 12:38
To: [log in to unmask]
Subject: Re: Benzo(a)pyrene[Scanned]
We have been informed by several LA's not to use SNIFFER particularly as
it does not have any dermal pathway and because of the limitations of
the model with respect to plant uptake.
We have used CLEA UK but this also provides very low numbers for
residential end use scenario although it is useful to be able to model
the dermal contact pathway without having to use the algorithms in CLEA
Briefing Note 1 in a separate calculation.
There is no avoidance of the fact that the DEFRA/EA tox information for
BaP is very very conservative.
Interesting who is conducting risk assessment these days. Even hauliers
now!
Adam Czarnecki
Director
REC Ltd
Osprey House
Broadway
Manchester
M50 2UE
Tel: 0161 868 1300
Fax: 0161 868 1301
Email [log in to unmask]
www.recltd.co.uk <http://www.recltd.co.uk/>
Rob Ashby wrote:
>Nik,
>
>We have used SNIFFER to calculate SSACs for a range of parameters.
>However with B{a)P I think that care is required when using SNIFFER.
>
>SNIFFER does not include a dermal uptake pathway, but incorporates a
>check to identify whether dermal is likely to be significant. The
>check indicates that dermal uptake is significant for B(a)P. Therefore
>we have also incorporated a number of additional calculations which are
>based upon data published in CLR10 and CLEA Briefing Note 1.
>
>It is my guess that if your haulier has calculated a threshold of
>7mg/kg B(a)P, he has not included all the potential exposure pathways.
>Our assessment procedure for apartments, which is based upon
>residential exposure, without up-take from vegetables, also indicates a
>SSAC between 1mg/kg and 2 mg/kg B(a)P.
>
>Trust this helps
>
>Rob Ashby
>Consulting Group Manager
>Enviros Consulting
>Tel 0161 874 3656
>Mob 07800 624 013
>
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>
>-----Original Message-----
>From: Contaminated Land Management Discussion List
>[mailto:[log in to unmask]] On Behalf Of Nik
>Reynolds
>Sent: 08 February 2006 15:39
>To: [log in to unmask]
>Subject: Benzo(a)pyrene
>
>We are currently reviewing the threshold proposals for topsoil for
>importation onto one of our clients sites. Normally we specify between
>1
>and 2mg/kg depending upon the proposed landuse, however we have been
>informed by our clients haulier that we are too conservative and an
>acceptable threshold of 7mg/kg for apartments is possible using a
>modified SNIFFER assessment. We do acknowledge that obtaining these
>low parameters is extremely difficult and does result in the rejection
>of much imported material.
>
>If this is so, fantastic, however thought i'd see if anyone has come
>across this?
>
>We have seen a risk assessment for 10mg/kg, however found that the
>index dose had been incorrected inputed.
>
>Appreciate any assistance any one can give. Maybe this could start to
>become part of the threshold banding to be used in the real world!!!!
>
>
>
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