Effect of Environmental Exposure on the Lead Levels in Human Blood in Kenya

Lead is one of the heavy metals associated with a number of health problems such as abdominal pains, constipation and loss of appetite, nausea, vomiting, insomnia, headache, irritability, dizziness and lead encephalopathy. The major source of lead into the environment is through emission from auto exhaust in countries still using leaded fuel, with other contributors being cigarette smoke, burning of lead battery castings, weathering, ceramic industries and paints. Therefore there is need for continued monitoring of the levels of lead in the environment and in people to determine the level of exposure. The aim of the study was to determine the effect of environmental exposure on the levels of lead in human blood in Nairobi City and Nyamira District, Kenya. The subjects who had lived in the study areas continuously for five years were randomly selected and recruited for the study. The study used a questionnaire to assess lead exposure factors of the recruits, while atomic absorption spectroscopy and differential pulse anodic stripping voltammetry were used for determining the lead levels. The subjects in Nairobi City Centre had the highest mean blood lead (BPb) level of 29.9 + 16.91 µg/l, while Nyamira Rural subjects had the lowest mean of 24.20 + 7.07 µg/l. The mean lead level of the subjects was statistically significant between Nairobi City Centre and Nyamira Rural (P < 0.01, df = 99). The smokers, those who travelled frequently, the users of glazed ceramics, those who worked in industries and those who lived near busy roads had higher levels of blood lead. The study provides an additional data pointing to elevated blood lead levels in environmentally exposed individuals. Keywords: Lead, environmental exposure, human blood, AAS, DPASV.

Effect of Occupation on the Levels of Lead in Human Blood in Kenya

The occupation an individual is involved in exposes him or her to different levels of lead from the work environment. The main occupation of the study subjects included working in the petrol stations, teaching, nursing, street hawking, doing clerical work, working in public vehicles, farming and schooling. The aim of the study was to determine the effect of occupation on the lead levels in human blood in Nairobi City and Nyamira District, Kenya. The subjects involved in the different occupations were randomly selected and recruited for the study. The study used a questionnaire to assess lead exposure factors of the recruits, while atomic absorption spectroscopy and differential pulse anodic stripping voltammetry were used for determining the lead levels. The street hawkers in Nairobi City centre had the highest mean blood lead level of 36.85?16.98 ?g/ dl while the teachers of Nyamira Town had the lowest mean blood lead level of 8.1?5.3 ?g/ dl. The study provides an additional data pointing to elevated blood lead levels in occupationally exposed individuals. Key words: Occupational exposure, BPb, AAS, DPASV

Occurrence and distribution of Organochlorine Pesticide Residues in Water and Sediments of Earthen Fish Ponds in South Western Kenya

Persistent organochlorine residues in the environment are a threat to ecological health of aquatic organisms and pose a health risk to both animals and human consumers. Organochlorine pesticides were determined in water and sediments collected during wet and dry season from selected riverine and earthen fish pond sites in high altitude catchment areas within Kuja River (Kenya) between August 2016–May, 2017. Analysis of DDT and metabolites, Hexachlorocyclohexanes (HCHs) isomers and cyclodienes using a gas chromatograph (GC), and electron capture detector (ECD), confirmed using GC - Mass Spectrometry (MS). Mean (± Standard error) results of DDTs, cyclodienes and HCHs in pond waters were:- below detection level (BDL) to 0.27±0.03µg/L, BDL to 0.11±0.00µg/L, and 4.39±1.01µg/L respectively; and BDL to 0.23±0.01µg/L, 1.20±0.005µg/L, and 1.71±0.02µg/L in river water respectively. Sediment mean OCPs contents were significantly (p<0.05) higher for Dieldrin (3.043±0.43µg/kg), Endrin (2.56±0.460µg/kg), Heptachlor (3.61±0.02µg/kg) DDT (2.97±1.32µg/kg), Endosulfan (6.31.27±1.051µg/kg), Methoxychlor (2.15±1.641µg/kg) and Lindane (2.96±1.32µg/kg), respectively. A longitudinal spatial distribution pattern was noted for both water and sediment OCPs contents, demonstrating that cyclodienes are predominant contaminants in point and non-point sources in water courses. The study recommends continuous monitoring of OCPs in upstream catchment areas for informed management and policy decisions on pesticide use. Keywords: Kuja-Migori River; Organic contaminants; Organochlorine Pesticide

First comprehensive study on total contents and hot water extractable fraction of selected elements in 19 medicinal plants from various locations in Nyamira County, Kenya

A large number of medicinal plants is traditionally known in Kenya and used for treatment of various diseases, for example diabetes, where metals are supposed to be involved in pathogenesis and therapy. Therefore, detailed investigation of the concentration of a large number of metals in medicinal plants is required for improved understanding and optimisation of the therapeutic role of metals and also to exclude potentially toxic effects. Our study focused on the determination of 30 selected elements in 19 medicinal plant species each collected from 3 sampling locations in Nyamira County, Kenya. The obtained comprehensive data set showed large variability and multivariate data analysis revealed that the differences in the elemental composition were stronger dependent on the plant species than on the sampling location. In addition, hot water extractions were performed to mimic the traditional preparation of medicine from the plants. It was found that the mean extraction efficiencies were below 20% except for B, Mg, P, K, Mn, Co, Ni, Cu, Zn, Rb, Mo, Cd and Tl, which are mostly essential elements apart from Cd and Tl. Sequential (ultra)filtration of the extracts was applied as novel approach for molecular size-fractionation of the extracted elemental species. The results indicate more than 50% low molecular weight species (3 kDa up to <5 μm) were detected for V, Cu, Al and Fe

Soil sorption and effects on soil microorganisms of thymol and carvacrol monoterpenes from essential oils of aromatic plants

To increase the biodiversity of agricultural systems, aromatic plants appear particularly promising as additional perennial crops in intercropping. They produce essential oils that contain monoterpenes, for example. These compounds have antibiotic properties that make them interesting for commercialisation as medicinal or pesticide products, but also carry the risk of undesirable effects on soil microorganisms and thus on essential soil functions. To investigate this, the monoterpenes thymol and carvacrol and a set of four typical agricultural soils were selected and soil sorption batch tests and soil toxicity tests were carried out to determine dose-response relationships. Sorption followed second order kinetics and was best described at equilibrium by the non-linear BET isotherm that distinguishes between monolayer and multilayer sorption of the non-polar compounds. While the kinetics were very fast with rate constants of 1.66 × 10−4 and 0.70 × 10−4 min−1 for thymol and carvacrol, the strength of sorption remained quite low (Kd 1.93–3.69), indicating a high mobility and bioavailability of the monoterpenes. In addition, the relation to single soil properties remained low, indicating a multivariate impact of several soil properties. Although thymol and carvacrol are isomeric compounds, they differed in the rate and strength of sorption as well as in the effects on five selected soil microbiological enzyme activities. In particular, carvacrol caused inhibition of enzyme activities, whereas thymol did not produce measurable or relevant effects in all cases. The effect concentrations of 10% and 25% percent inhibition (EC10, EC25) ranged from &lt;1 µg to several grams per Gram of soil and hormesis effects were also observed at low concentrations. On the one hand, this indicates only low toxicity; on the other hand, several of the defined effect thresholds can be reached or exceeded by expected environmental concentrations. This may harbour a risk of adverse effects, but may also have a phytosanitary effect, which requires further research