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Improving risk assessments for manufactured gas plant soils by measuring PAH availability
Author(s) -
Stroo Hans F.,
Nakles David V.,
Kreitinger Joseph P.,
Loehr Raymond C.,
Hawthorne Steven B.,
Luthy Richard G.,
Holman HoiYing,
LaPierre Adrienne
Publication year - 2005
Publication title -
integrated environmental assessment and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 57
eISSN - 1551-3793
pISSN - 1551-3777
DOI - 10.1897/2004-009r.1
Subject(s) - pyrene , environmental remediation , environmental chemistry , environmental science , soil water , contamination , chemistry , soil science , ecology , organic chemistry , biology
Abstract Remediation of soils at oil‐gas manufactured gas plant (MGP) sites is driven primarily by the human health risks posed by the carcinogenic polycyclic aromatic hydrocarbons (PAHs), particularly benzo[a]pyrene (BaP), that are associated with lampblack residues. Although PAHs on lampblack are tightly sorbed, risk assessments do not account for this reduced availability. A multi‐investigator study of 7 oil‐gas MGP site soil samples demonstrated that the dermal and ingestion absorption factors are far lower than current default assumptions used in risk assessments. Using these sample‐specific absorption factors in standard risk assessment equations increased risk‐based cleanup levels by a factor of 72 on average (with a range from 23 to 142 times the default level). The rapidly released fraction of the BaP in each sample, as measured by supercritical fluid extraction, was closely correlated ( r 2 = 0.96) to these calculated cleanup levels. The weight of evidence developed during this research indicates that the risks posed by PAHs on lampblack are far less than assumed when using default absorption factors and that a tiered evaluation protocol employing chemical analyses, chemical release data, and in vitro bioassays can be used to establish more realistic site‐specific criteria.