The Scientific World Journal / 2018 / Article / Tab 2

Research Article

Sequential Extractions and Toxicity Potential of Trace Metals Absorbed into Airborne Particles in an Urban Atmosphere of Southwestern Nigeria

Table 2

Definitions and values of variables used in the estimation of human exposure.

Symbols DefinitionValues

Concentrations of metals in dust (mg/kg)
ABSAbsorption factor (unitless)0.001 (inorganic)
ATAverage time (Non carcinogenic ingestion only) yr & day/yrED × 365 (noncarcinogenic)
  × 365 (noncarcinogenic)
BWAdult body weight (kg)70 (adults)
15 (children)
SLSkin adherence factor (mgcm−2)0.2 (children)
0.07 (adults)
CFUnit conversion factor (kg/mg)10−6
Unit conversion factor dermal (kgcm2)/mgm20.01
EDExposure duration of noncarcinogenic ingestion only (yr)24 (adults),
6 (children)
EFExposure frequency (day/yr)350
SAAdult surface area (cm3)5700 (adults)
2800 (children)
Ingesting rate for adults (mg/day)100 (adults)
200 (children)
Inhalation rate (m3/day)7.6 (children)
20 (adults)
PEFParticulate emission rate (m3/kg)4.28 × 109
Absorbed chronic reference dose (mg/kg-day)Metal specific
Inhalation chronic reference dose (mg/kg-day)Metal specific
Oral chronic reference dose (mg/kg-day)Metal specific
Absorbed dose slope factor (mg/kg-day)−1Metal specific
Inhalation slope factor (mg/kg-day)−1Metal specific
Oral slope factor (mg/kg-day)−1Metal specific