Sources, distribution, and risk assessment of organochlorine pesticides in Nairobi City, Kenya.

The distribution and sources of organochlorine pesticides (OCPs) in air and surface waters were monitored in Nairobi City using triolein-filled semipermeable membrane devices (SPMDs). The SPMDs were extracted by dialysis using n-hexane, followed by cleanup by adsorption chromatography on silica gel cartridges. Sample analysis was done by GC-ECD and confirmed by GC-MS. Separation of means was achieved by analysis of variance, followed by pair-wise comparison using the t-test (p≤ 0.05). The total OCPs ranged between 0.018 - 1.277 ng/m3 in the air and Kibera > Industrial Area > City Square > Ngong' Forest. However, these were lower than the USEPA acceptable risks, 10-6 - 10-4. This study concluded that atmospheric OCPs did not pose significant cancer risks to the residents.

Impacts of climate-induced changes on the distribution of pesticides residues in water and sediment of Lake Naivasha, Kenya.

This study reports evidence of increased chlorpyrifos contamination in sediment and water in Lake Naivasha following its intensive application in the horticultural farms in the catchment area. Analytical results show that levels of chlorpyrifos residues were influenced by climate-induced rainfall pattern with higher levels reported during period of heavy precipitation with significant decrease during low rainfall. On average, the levels ranged between 14.8 and 32.8 ng g(-1) in sediment during rainy season compared to a range of 8.5-16.6 ng g(-1) in the dry season. Additionally, the mean concentration of chlorpyrifos in water ranged between 8.61 and 22.4 µg L(-1) during rainy season and below detection limit (bdl) -13.6 µg L(-1) in dry season as quantified by enzyme-linked immunosorbent assay. Meanwhile, independent t test analysis indicated that there was significant difference in concentration at p ≤ 0.05 between the seasons with respect to sediment and water samples. This demonstrated that climate-induced variations had considerable influence on contamination. While diazinon and carbofuran were equally applied intensively, their levels were below the detection limit in the all the samples analyzed. ELISA results were validated by the capillary-HPLC photodiode-array detector instrument analysis, and statistical comparison showed no significant difference between them. It was evident that chlorpyrifos residues determination in water and sediment by ELISA can be a useful strategy in environmental management and monitoring program, and a complimentary analytical tool to high performance liquid chromatography. Levels of chlorpyrifos detected in sediment and water were found to exceed recommended criteria for protection of aquatic life and preservation of water quality and may be hazardous if not regularly monitored.

Antinociceptive and antiplasmodial activities of cassane furanoditerpenes from Caesalpinia volkensii H. root bark.

The chloroform and ethyl acetate extract (100mg/kg) of Caesalpinia volkensii H. exhibited significant (P ≤ 0.05) antinociceptive activities using hot plate and writhing tests in mice while the later showed antiplasmodial activity (IC(50) 0.23 ± 0.07 and 4.39 ± 2.49 µg/ml) against chloroquine sensitive (D6) and chloroquine-resistant (W2), respectively. Two new furanoditerpenes [rel. 1ß,5α-dihydroxyvoucapane (1) and rel. 1ß,6ß-dihydroxyvoucapane; 19ß-methyl ester (2)] together with seven known compounds [voucapane (3), voucapan-5-ol (4), deoxycaesaldekarin C (5), caesaldekarin C (6), 5-hydroxyvinhaticoic acid (7), triacontanyl-(E)-ferulate (8), triacontanyl-(E)-caffaete (9) and 30'-hydroxytriacontanyl-(E)-ferulate (10)] were isolated from the two extracts. The administration of 3, 4, 5 and 6 (100mg/kg i.p) caused a significant (P ≤ 0.05) reduction in the number of writhing episodes induced by acetic acid and (P ≤ 0.01) increased pain latency threshold in hot-plate test compared to control. However, the pure compounds indicated relatively (P ≤ 0.05) low antiplasmodial activity. The phytochemical constituents from the root bark of C. volkensii had better analgesic properties than antimalarial properties, justifying the use of the plant root bark as a remedy for pain.