Risk-based BTEX screening criteria for a groundwater irrigation scenario
Title:
Risk-based BTEX screening criteria for a groundwater irrigation scenario
Author:
Walden, Terry Spence, Lynn
Appeared in:
Human and ecological risk assessment
Paging:
Volume 3 (1997) nr. 4 pages 699-722
Year:
1997-09
Contents:
A human exposure activity for which risk-based cleanup goals are typically not defined is the 'irrigation' scenario. This refers to residential use of contaminated well water for watering lawns or gardens at homes having potable water supplied by their community. Exposures from ingestion, dermal contact or vapor inhalation by a child playing under the sprinkler, from vapor inhalation by an adult gardening downwind of the sprinkler, and from adult/child ingestion of vegetables grown in a garden irrigated by the sprinkler have been modeled. Screening level target values for BTEX compounds in the ground-water have been derived for reasonable exposure assumptions associated with a child receptor, an adult receptor, and a receptor living as both a child and adult in the house over a 30-year duration. Due to existing legislative precedents and growing regulatory acceptance worldwide, a target cancer risk level of 1 x 10-5 is adopted. At this level, the cleanup target for benzene is 1.1 mg/1 for the child and 3.2 mg/1 for the adult. For the combined child/adult case, the target is 0.85 mg/1. Based on a hazard index of one, the TEX compounds have target levels ranging from 9.5 to 1090 mg/1 for the three receptor scenarios. Note that these numeric values are considered appropriate for screening purposes to determine whether or not an irrigation risk may be present. While shown to be conservative, they are only applicable if the assumptions used are pertinent to the site-specific situation being evaluated.
Journal description