The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in Densu River Basin in Ghana were measured using gas chromatograph. Surface water samples were collected from nine stations, namely, Potroase, Koforidua Intake, Suhyien, Mangoase, Asuboi, Nsawam Bridge, Afuaman, Ashalaga, and Weija Intake in the Densu Basin. Total PAH concentrations varied from 13.0 to 80.0 μg/mL in the Densu River, with a mean value of 37.1 μg/mL. The two- to three-ring PAHs (low-molecular-weight PAHs) were found to be dominant in the Densu River Basin. Total PAH concentrations showed the following pattern: Koforidua Intake (80.0 μg/mL) > Asuboi (50.8 μg/mL) > Afuaman (47.9 μg/mL) > Weija Intake (45.0 μg/mL) > Suhyien (27.6 μg/mL) > Nsawam (23.5 μg/mL) > Ashalaja (22.9 μg/mL) > Potroase (23.3 μg/mL) > Mangoase (13.0 μg/mL). According to the Agency for Toxic Substances and Disease Registry (ATSDR), background levels of PAHs in drinking water supplies in the USA range from 0.004 to 0.024 μg/mL. PAH levels from all sites exceeded the range set by ATSDR. B[a]P contributed the highest carcinogenic exposure equivalent (0.3 μg/mL), followed by B[a]A (0.132 μg/mL) and B[b]F (0.08 μg/mL), contributing 52.6%, 23.2%, and 4.6%, respectively, of the total carcinogenicity of surface water PAH in the Densu River Basin. The carcinogenic potency was estimated to be 0.57 μg/mL. The presence of PAHs was an indication of the water sources being contaminated, with potential health implications.

Arsenic (As) analysis of 150 boreholes in the southeastern part of Ghana (Accra, Eastern and Volta regions) revealed low to medium concentrations in the range of 2-39 µg l-1 , with only 2% of boreholes tested having arsenic concentration exceeding 10 µg l-1 of the WHO (2004) maximum permissible level of arsenic in drinking water. The measurements were carried out in the field using the Wagtech Arsenator field test kit (Wag-We 100500) equipment, which gives direct readout of arsenic concentration in the critical range 2-100 µg l-1. Arsenic concentrations were in the range < 2-39 µg l-1 with mean (< 2 µg l-1) and median (< 2 µg l-1). Out of 150 samples analysed, 147 had As concentration below 10 µg l-1. Three boreholes in the Recent Sand Formation in southern Volta Region at Atitekpo, Mafi Devime and Woe Aklorbordzi had arsenic concentrations of 28 µg l-1 , 19 µg l-1 and 39 µg l-1 , respectively. Though the sample of boreholes tested was only approximately 10% of the total number of boreholes in the study, the distribution within the sample makes the generalization that the risk of arsenic contamination of rural water supply in southeastern Ghana is generally low plausible. In spite of this assertion, boreholes in the Recent Sandy Formation have to be critically assessed to determine the extent of arsenic contamination and, if possible, monitored.