UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON. D.C. 20460
JAN 27
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OSWER Directive 9850.4
MEMORANDUM
SUBJECT: Interim. FinaV^u^dance for Soil Ingestion Rates
FROM:
TO:
J. Winston Porter
Assistant Administrator
Regional Administrators
Regions I-X
Risk assessments are conducted at Superfund sites as part of
Remedial Investigations required by the Proposed National
Contingency Plan, and may be conducted at RCRA facilities
undergoing corrective action as described in the soon-to-be
Proposed RCRA Corrective Action Rule, to estimate the risk from
exposure to substances. Within the risk assessment, an exposure
assessment is performed which is based on various exposure
assumptions such as soil ingestion rates. This interim final
guidance provides recommended soil ingestion rate assumptions of
0.2 gram per day for children aged 1 year through 6 years and 0.1
gram per day for older age groups, in the absence of site
specific data.
Introduction and Background;
Currant Agency guidance that might be used within the OSWER
programs for developing risk assessments provides ranges of
different ceil ingestion rates. However, no guidance is provided
regarding the selection of an ingestion rate from within these
ranges. In order to promote consistency within Agenc- guidance
and the use of realistic, conservative exposure scenarios
throughout the CERCLA and RCRA programs, this interim final
guidance provides specified assumptions to be made for soil
ingestion rates for both children and adults.
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OSWER Oir. 9850.4
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This interim final guidance supersedes previous program
related guidance (Superfund Public Health Evaluation Manual,
October, 1986, OSWER Directive 9285.4-01) only with reference to
soil ingestion rates and should be used by regional staff who are
responsible for conducting and evaluating risk assessments in
OSWER related programs. This interim final guidance is based on
the most recent reliable data available on soil ingestion rates.
It may be revised to reflect new. data the Agency may review that
would significantly affect risk, assessment results.
In developing exposure scenarios used in program risk
assessments, a soil ingestion rate of 0.1 grams per day should be
used for adults and a soil ingestion rate of 0.2 grams per day
should be used for children who are one year through six years of
age. These rates are based on the most recent reliable data
reviewed by the Agency, and represent reasonably constr/dtive
values. This guidance does not address children who exnibit
abnormal mouthing behavior (pica). The occurrence of pica
behavior and the associated rates of soil ingestion have not been
well defined, without this information, risk cannot be
quantified for children with pica behavior.
There may be cases where site- or facility-specific data
exist on soil ingestion rates or the occurrence of pica behavior
of children. In these cases, deviation from this guidance may be
appropriate. However, the data supporting this deviation should
be provided within the related risk assessment. If the data are
provided by the potentially responsible party in the Superfund
program or the owner/opera tor in the RCRA program, these data
should be reviewed and verified by the risk assessment experts in
the Regions, who may also choose to consult with Headquarters.
Contacts:
If there are any general questions regarding this interim
final guidance, please contact Sherry Sterling, (FTS) 382-4826,
of my staff. For program specific information, the following
staff may be contacted:
RCRA Alec McBride (FTS)382-7045
CERCIA/Fund Dave Bennett (FTS)475-9486
CERCLA/Enforcement Sherry Sterling (FTS)382-4826
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OSWER Directive 9850.4
cc: Bruce Diamond, OWPE
Henry L. Longest II, OERR
Sylvia Lowrance, OSW
Timothy Fields, ERD
Stephen Lingle, HSED
Russell H. Wyer, HSCD
Joseph carra, PSPD
David Bussard, HMD
Lloyd Guerci, CED
Susan Bromm, RED
Directors, Waste Management Divisions, Regions I, IV, V,
VII, VIII
Director, Emergency and Remedial Response Division, Region
II
Directors, Hazardous waste Management Divisions, Region III
VI
Director, Toxics and Waste Management Division, Region IX
Director, Hazardous Waste Division, Region X
CERCLA Branch Chiefs, Regions I-X
RCRA Branch Chiefs, Regions I-X
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