The distribution of organochlorine pesticides in marine samples along the Indian Ocean coast of Kenya.

The concentrations of organochlorine residues of lindane, aldrin, alpha-endosulfan, dieldrin, endrin, p,p'-DDE, p,p'-DDD and p,p'-DDT in samples of seawater, sediment, fish and seaweed from different locations along the coast of Kenya are discussed in relation to the geographical location of the sampling sites and potential sources of residue over a period of two years. All sediment samples were found to contain very low levels of organic carbon except those sampled from Sabaki River that had high (4.7%) organic carbon due to greater primary activity. Most of the pesticides residues (112 samples analysed in 1997 and 258 analysed in 1998/99) were detected in fish, water, sediments and seaweed. The concentration of some residues was higher during the wet season than the dry season in 1997, but no marked seasonal variation was observed in 1998/99. Lindane, aldrin, p,p'-DDT and p,p'-DDE were the most frequently observed residues in all samples while alpha-endosulfan, dieldrin, p,p'-DDD and endrin were either present low concentrations or absent in most samples. Water samples had the lowest concentrations of residues (range 0.503 - 9.025 ng g(-1)). Sediments had the second highest levels of pesticides residues with a range of 0.584 - 59.00 ng g(-1) while fish lipid content had the highest levels of residues in 1989/99 with p,p'-DDT concentration of 1011 ng g(-1) and 418 ng g(-1) p,p'-DDD in Siganus rivulatus.

Accumulation, distribution and metabolism of 14C-1,1,1-trichloro-2, 2-, bis-(p-chlorophenyl)ethane (p,p'-DDT) residues in a model tropical marine ecosystem.

Accumulation, distribution and metabolism of ring labelled, 14C-1,1,1,-trichloro-2,2-bis(p-chlorophenyl)ethane (p,p'-DDT) in a model marine aquatic ecosystem consisting of seawater, sediment, oysters (Isognomonon alatus) and Humbug fish (Dascillus aruanus) were studied in the laboratory. 14C-p,p'-DDT distributes rapidly in the ecosystem immediately after application on the water surface with reduction of its concentration in the water phase from 1.18 ng g(-1) to 0.71 ng g(-1) after 2 hours and an increase in its content in the sediment and oysters. The bioconcentration factor reached a maximum of 19 x 10(3) in oysters, and 1657 in Humbug fish after 24 hours. The sediment concentration reached 117 ng g(-1) after 168 hours from start of application. A peak bioconcentration factor of 111 x 10(3) was calculated after 120 hours when 0.24 mg kg(-1) of 14C-p,p'-DDT was maintained through dosing every 24 hours with 0.002 mg kg(-1) of a mixture of labelled and non-labelled pesticide. The rate of depuration of accumulated 14C-p,p'-DDT sediment residues was up to 78.3% after 24 hours while oysters lost only 14.0% during the same period. The loss in Humbug fish was only 22.2% in three days. Volatilisation and sorption losses from seawater alone (without sediment/biota) were found to be very high in the range of 73.8 - 91.5% over 24 h for p,p'-DDT in aerated and nonaerated ecosystem. Gas chromatograph and TLC analysis of water, sediment and oyster samples revealed presence of p,p'-DDT and substantial amounts of p,p'-DDE and p,p'-DDD three days after pesticide dosage.

Animal health problems attributed to environmental contamination in lake Nakuru National Park, Kenya: a case study on heavy metal poisoning in the Waterbuck Kobus ellipsiprymnus defassa (Ruppel 1835).

A study was conducted in which samples of soil, forage, as well as serum, bone, kidney, and liver of waterbuck were collected from Lake Nakuru National Park. The objective was to determine the ecosystem health status in order to establish the causes of animal health problems previously recorded in some sections of the Park. Trace element analysis in serum indicated occurrence of copper (Cu) deficiency in the north and eastern sections of the Park where mean values were marginal (range: 0.36-0.81, mean: 0.62 mg/l) compared to concentrations recorded in the western part of the Park (range: 0.69-1.48, mean: 1.22 mg/l). Bone analysis on dry matter basis (DM) indicated higher (p < 0.01) levels of cadmium (Cd, 0.437 mg/kg), fluoride (F, 3178 mg/kg), and lead (Pb, 20.62 mg/kg) in animals from the east compared to those from the west (0.002, 1492, 4.87 mg/kg, respectively), suggesting heavy exposure. In addition, samples from the east had much lower than normal calcium (Ca)-to-phosphorus (P) ratios (mean: 1.9:1) compared to those recorded in the west (2.2:1), suggesting poor bone mineralization. There was a higher concentration of Cd in the kidney (16.24 mg/kg, p < 0.05) and Pb in the liver (58.3 mg/kg, p < 0.01) in animals from the east compared to those in the west (12.92 and 36.2 mg/kg, respectively), but the converse was true of Cu. The liver Cu status was better in animals from the west with, concentrations (mean: 21.7 mg/kg) being about twice those recorded in the east (11.9 mg/kg DM). Forage analysis revealed prospects of Ca, P, and Cu deficiencies in the entire Park. However, in the northeastern section of the Park (measuring 50 ha) where waterbuck residence times are high, forage concentrations of Cd (0.31 mg/kg DM), molybdenum (Mo, 7.20 mg/kg DM), Pb (2.88 mg/kg DM), and zinc (Zn, 126 mg/kg DM) were an order of magnitude greater (p < 0.01) than the levels recorded in the rest of the Park (ranges: 0.133-0.165, 3.69-5.61, 0.485-0.621, 11.6-17.4 mg/kg DM, respectively). These disparities were attributed to a higher soil concentration of Cd (2.77 mg/kg DM), Pb (85.1 mg/k DM) and Zn (1414 mg/kg DM) in this section compared to the rest of the Park (ranges: 0.10-0.15, 5.02-6.26, 1.49-5.44 mg/kg DM, respectively), and strongly suggest heavy metal contamination as the source of animal health problems in the Park.

Worker exposure and health risks from volatile organic compounds utilized in the paint manufacturing industry of Kenya.

This study provides a means for the evaluation of cleaner manufacturing and the provision of cost-effective worker health improvements in developing nations. Individual worker exposure to volatile organic compounds was measured in the paint manufacturing plants of Nairobi, Kenya. A variety of different paint production jobs were monitored, including laboratory researchers, mixers, tinters, fillers, cleaners, raw materials deliverers, and resins producers. Exposure levels were calculated based on a time-weighted average over an entire 8-10 hour workday. The paint solvents used can cause both acute and chronic health problems for the workers exposed. For example, over half of the organics monitored, i.e. benzene, styrene, and xylene, exhibit carcinogenic properties. The lifetime cancer risk from exposure to these paint solvents was estimated utilizing published cancer potencies, and the risks range from 1.90 x 10(-4) for raw materials deliverers to 2.60 x 10-2 for cleaners. The highest exposure tasks included cleaning the mixing vats and mixing the paint product, ranging from risks of 8.5 x 10(-4) to 2.6 x 10(-2), providing evidence that solvent exposure occurs due to point sources. Because of this, simple and inexpensive technologies should significantly reduce the excess exposure of workers in these manufacturing facilities. The cost of minor-innovations in the plants themselves, such as fans, drum and mixing vat covers, and respirators, could amount to as much as five times less than the estimated cost of treating workers who develop cancer due to paint solvent exposure.