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E-M:/ Dioxin levels in soil

Enviro-Mich message from "Paul Hanly" <PNARH@bigpond.com>

for those interested in the Midland dioxin clean up.

The NZ government has tested soils around the Ivor Watkins Dow plant in
Paritutu in New Playmouth:
Table D.1 of “Dioxin Concentrations in Residential Soil, Paritutu, New
Plymouth” September 2002 contains a table of soil standards (see below).

Removing adjustments to reduce cancer risk to 1 in 100,000 rather than 1 in
a million the info is below.

It is noted that with the single exception of Japan, all soil standards set
since 2000 have been below 90 parts per trillion.

All standards set before the WHO 1998 TDI issued were drafted at a time when
the TDI was over 400% of the current Australian Federal Department of Health
and Ageing recommended TDI of the equivalent of 2.3 pg/kg/bw/day. On a
simplistic basis the an adjustment of soli standards to 250 pp trillion
would seem warranted.

Country - Residential soil criteria - Comment [Reference]
New Zealand - 1,500 ng I-TEQ/kg - Present criterion - set as an interim
value in the timber treatment guidelines. Currently under review (as at Sept
2002). (MfE/MoH, 1997).
Germany  - 1,000 ng I-TEQ/kg - Set as an “action value” by the Federal Soil
Protection and Contaminated Sites Ordinance (BbodSchV) (BMU, 1999).
Japan - 1,000 ng TEQ/kg Environmental Quality Standard set under the Law
Concerning Special Measures against Dioxin (Law No. 105 of 1999) (MoE, 2001)
Canada - 4 ng TEQ/kg Soil Quality Guideline. Derived using ambient
background concentrations; i.e. is not effects based. (CCME, 2001)
United States Federal Environmental Protection Agency (USEPA) - 1,000 ng
TEQ/kg Preliminary Remediation Goal. Based on criterion developed by
Kimbrough et al. (1984).
USEPA Region 6 - 3.9 ng/kg (for TCDD)1 Screening Level for 2,3,7,8-TCDD [US
EPA R6,2001]
USEPA Region 9 - 3.9 ng/kg (for TCDD)1 Preliminary Remediation Goal for
2,3,7,8-TCDD (US EPA R9, 2000)
Michigan Department of Environmental Quality - 90 ng TEQ/kg Direct Contact
Criterion. Derived based on a 1 in 100,000 cancer risk. (DEQ, 1998)
US Department of Health and Human Services - Agency for Toxic Substances and
Disease Register
50 ng TEQ/kg Screening level
>50 <1,000 ng TEQ/kg Evaluation level
>1,000 ng TEQ/kg Action level. (ATSDR, 1998).

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