Abstract:
Polychlorinated biphenyls (PCBs) in surface soil samples from the Central
Region of Ghana were analyzed to assess their distribution, levels and health
effects. The soil characteristics were analyzed. Soils samples were digested
with a mixture HN03 and HCI04 and the metals analyzed using Varian 235
AAS. The PCBs were extracted with (1:1) hexane:acetone mixture, cleanup
with H2S04, 5% KMn04 and copper, and then eluted from a silica gel column
with hexane:dichloromethane (97:3% v/v). The PCBs were analyzed using a
gas chromatograph equipped with 63Ni electron capture detector (GC - ECD)
model CP 3800. The PCBs were dominated by penta and tetra PCBs
homologous. The concentration of PCBs for the region was 7.99±0.38 /lg/kg.
The levels for the vertical distribution were 9.15± 0.52 /lg/kg for (0-10 cm),
7.55± 0.56 /lg/kg and 7.82 ± 0.55 ug/kg for the 10-20 cm and 20-30 cm subsurface
soils. The pH, clay, silts and sand content of the soils correlated
positively with the PCB congeners. The effective cation exchange capacity
and moisture showed negative correlation. There were no significant
correlations between organic matter, exchangeable base, metals and the PCB
congeners or LPCB at the 0.05 level. The levels of PCBs were below the soil
contact value of 25 mg/kg. The toxicity equivalents of PCB- 118 were all very
low. Most of the soils in residential areas had hazard Index greater than one.
The estimated lifetime cancer risk to a Reasonable Maximum Exposure
(RME) individual via the complete exposure (skin contact) was very low, and
ranged between 3.0E-l1 and 3.0E-IO for adult resident and 5.4E-IO to
5.3E-09 for children resident, implying that the levels of exposure to soil
PCBs are acceptable.
