Soil ingestion pathway

Where Cf FDA guideline for PBB concentration In fat (26), the SPPPLV for the soil ingestion pathway is then... 

Bioavailability and Risk of Arsenic Exposure by the Soil Ingestion Pathway... 

As an alternative to the assumption of a one-time exposure for 1,000 h at the time of facility closure, permanent occupancy of a disposal site following loss of institutional control could be assumed (see Section 7.1.3.4). The assumption of chronic lifetime exposure would affect the analysis for hazardous chemicals that induce deterministic effects only if estimated intakes due to additional pathways, such as consumption of contaminated vegetables or other foodstuffs produced on the site, were significant. Based on the results for lead in Table 7.8, an intake rate from additional pathways of about 50 percent of the assumed intake rate by soil ingestion, inhalation, and dermal absorption would be sufficient to increase the deterministic risk index above unity. The importance of additional pathways was not investigated in this analysis, but they clearly would warrant consideration. The increase in exposure time during permanent occupancy does not otherwise affect the analysis for chemicals that induce deterministic effects, provided RfDs are appropriate for chronic exposure, because chronic RfDs incorporate an assumption that the levels of contaminants in body organs relative to the intake rate (dose) are at steady state. 

Other potential pathways of exposure-air inhalation, ingestion of water and soil, and dermal contact with soil-are much less significant to total daily intake of dioxins. PCDD/F intake via air inhalation, water ingestion and soil ingestion is estimated to be 3.2 pg TEQ d 1 (2-3% of total daily intake).38 Dermal contact with soil is negligible, however, constituting an estimated daily intake of 0.15pg TEQ d-1.38... 

A baseline risk assessment is conducted to assess the potential human health and environmental impacts associated with soil contamination. The primary exposure pathways evaluated for explosives contaminated surface soils are dust inhalation, soil ingestion, and dermal absorption. Reasonable Maximum Exposure (RME) concentrations are based on the 95% upper confidence interval (UCI) on the arithmetic mean of soil sampling data. The land use scenarios quantitatively evaluated may include industrial and residential use, utilizing EPA standard default exposure parameters. 

Soil ingestion is likely the only unique exposure pathway for children. Additional studies concerning bioavailability of manganese from soil would provide important information concerning the proportion of the total daily manganese intake that could originate from ingested soils. 

Incidental soil ingestion by children is an important pathway in assessing public health risks associated with exposure to arsenic-contaminated soils. Incidental ingestion of soil represents the principal direct pathway for exposure to nondietary sources of As in contaminated areas. The importance of soil ingestion by children as a health issue has been reported by numerous researchers and fully illustrates the importance of this pathway in terms of subsequent chemical exposure (4-8). 

A short overview of radionuclide sources, decay paths, ingestion pathways and behaviors in soils and plants follows Brady et al. (1999) and others as cited. 

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