Page 78 - {PDF Title}

Hossain, et al.

influence of other contributing factors in the assessment C IREFED
w
system. A parameter is considered non-polluting when CDI Ingestion BW AT (IX)
20
the NPI value is ≤1. The NPI was computed using
35
Equation VII: C SAK ET EF ED CF

CDI Dermal w p BW AT (X)
NPI P () 2 ( P imax ) 2 (VII)
1
2 where CDI ingestion/dermal is expressed in µg/kg/day; C
w
is the measured concentration of the contaminant in
where the single factor index (P ) represents the water (µg/L); IR is the ingestion rate; EF denotes the
1
average value of the single-factor pollution index, and exposure frequency (day/years); ED is the exposure
P imax represents the maximal single-item pollution index duration (year); BW is the average body weight (kg);
among the pollutants at a given sampling point. P was
1
calculated using Equation VIII: AT refers to the average time (day); SA is exposed
skin-surface area (cm ); ET is the exposure time
2
C (h/event); CF is conversion factor (L/cm ); and K is
3
P = S 1 (VIII) permeability coefficient (cm/h). Table 2 presents the
p
1
i
input assumptions and values used to calculate CDI for
where C is the measured concentration of the targeted ingestion and dermal absorption in adults and children.
i
pollutant, and S is the standard permissible limit of that
i
parameter. 2.9.2. HQ
The HQ is the ratio of CDI to the reference dose
2.9. Estimation of non-carcinogenic human health risks (RfD) for a given contaminant, expressed as follows
38
2.9.1. Chronic daily intake (CDI) (Equation XI):
The United States Environmental Protection Agency
defines a human health risk assessment as “the process HQ = CDI (XI)
of estimating the nature and probability of adverse ingestiondermal/ RfD
health effects in humans who may be exposed to
chemicals in contaminated environmental media, where RfD represents the RfD for the corresponding
37
now or in the future.” In this study, iron and arsenic heavy metals. The RfD for iron is 700 µg/kg/day,
36
were used to determine the non-carcinogenic health and arsenic is 0.3 µg/kg/day. The HQ values were
39
hazards associated with direct consumption and dermal categorized as follows: (i) negligible risk (HQ < 0.1);
absorption from pipeline-supplied water samples. The (ii) low risk, (0.1 < HQ < 1.0); (iii) moderate risk
CDI was calculated using Equations IX and X : (1.0 < HQ < 4.0), and (iv) high risk (HQ > 4.0). 40
37
Table 2. Parameters, input assumptions, and values for chronic daily intake calculation via dermal
absorption and ingestion for adults and children
Parameter Ingestion Dermal absorption References
Adult Children Adult Children
Measured metal concentrations (µg/L) - - - - -
Ingestion rate (L/day) 3.5 1.32 - - 37,38,66
Dermal permeability coefficient (cm/h) Iron: 1×10 , - -
−3
Arsenic: 4×10 −4
Exposure time (h/event) 0.58 1 - -
Skin-surface area (cm ) 18,000 6,600 - -
2
Exposure duration (year) 30 6 30 6
Exposure frequency (day/years) 365
Conversion factor (L/cm ) 0.001 - -
3
Body weight (kg) 57.5 15 57.5 15
Average time (day) 10,950 2,190 10,950 2,190

Volume 22 Issue 1 (2025) 72 doi: 10.36922/ajwep.8163