Jane Murungi

Use of human nails as bio-indicators of heavy metals environmental exposure among school age children in Kenya

Metal pollution and its health effects present a challenge currently facing the developing countries. Metal poisoning is usually difficult and expensive to assess or screen in these countries due to limited resources, which means that policies, guidelines, regulations and institutional managements are limited. Hair and nail as biopsy materials were suggested as more attractive biomarkers in assessing heavy metals environmental exposure. This paper deals with quantitative determination of lead (Pb), cadmium (Cd), calcium (Ca), zinc (Zn), and iron (Fe) in fingernails of children (n=200) in urban and rural areas using atomic absorption spectrometry. Factors that were suspected to influence the accumulation of Pb and Cd in children were obtained through a questionnaire. The mean levels of heavy metals in children in urban areas were found to be higher (27.5+/-1.8 microg/g Pb and 0.73+/-0.08 microg/g Cd) than in rural areas (19.7+/-0.9 microg/g Pb and 0.44+/-0.06 microg/g Cd). The difference was significant (P<0.05; DF=168, t-test). Other factors that were found to have significant influence were socio-economic background, health conditions, dietary habits and environmental risk exposure. The results also showed that the school location has more influence on the heavy metals level than the area of residence. The children in a school near the highway were found to have a mean of 34.4+/-3.5 microg/g Pb as compared to those who lived near the highway (31.6+/-2.8 microg/g Pb), however the difference was not significant (P>0.05), suggesting a common source of contaminants in the areas. The correlation results also indicated that a high level of Pb in the nail influenced negatively Zn and Fe but not Ca levels (R=-0.256 Zn; -0.188 Fe) while high levels of Cd had a negative relationship with Fe only (R=-0.241). The association of toxic metals in the nails of children with environmental exposure, and nutritional status implies that policies and actions to reduce heavy metal levels must be implemented and reinforced to address the health issues affecting children and by extension the general public in this country.

Elemental Analysis of Soft Plaque and Calcified Plaque Deposits from Human Coronary Arteries and Aorta

Abstract Twenty-five samples of soft plaque and calcified plaque deposits from human hearts or aorta were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS). The determined elements were Ca, P, Na, K, Mg, Zn, Cu, Ba, Pb, Fe, Al, Si, and S. Results showed that the concentration of all elements in the soft plaque was at the micromolar level. In the calcified deposits, the concentrations of Ca and P were at least an order of magnitude higher than the soft plaque, but the other elements were at the same order of magnitude. In the calcified plaque the molar ratios of Ca/P suggested that a significant portion existed as hydroxyapatite Ca10(PO4)6(OH)3. However, their absolute concentrations indicated that this compound was not a major component of the plaque although it may play a major role in determining the crystal structure of the deposit. In some samples the Ca/P ratio was too high to conform to hydroxyapatite. In others it was too low. This indicated that both the calcium and phosphorus existed in other chemical forms which varied from sample to sample. In the soft tissue the P level was high indicating it existed primarily in chemical forms other than hydroxyapatite. The presence of homocysteine is often associated with heart disease. However, the low levels of sulfur indicate that although it may be present, it is not a major component of the plaque, but may nevertheless play an important role in its formation.

Use of Low Cost Soil Amendments Reduces Uptake of Cadmium and Lead by Tobacco (Nicotiana tabacum) Grown in Medially Polluted Soils

The study explored the use of low cost soil amendments in reducing lead and cadmium uptake in tobacco. High levels of these metals in tobacco are of concern because of their toxicity and cumulative nature in tobacco consumers. Tobacco was planted in soils amended with cow manure and hydroxyapatite (HA), and non-amended sandy-loamy soil containing 60.57±3.74 μg/g lead and 33.95±0.49 μg/g cadmium in field and pot experiments. Tobacco leaves harvested after 75 days were dried, acid digested and their metal contents determined using atomic absorption spectroscopy (AAS). Cow manure reduced cadmium uptake by 67.20% and 71.75% in field and pot experiments while 1.5% HA reduced lead uptake by 39.69% in field experiments. Pot experiments had higher metals uptake than field experiments while fertilizer treatments recorded highest uptake. However, the levels were within WHO/FAO limits, indicating that amending medially polluted soils with cow manure and HA results in safe harvests of tobacco.

Alum treated grey water for toilet flushing, mopping and laundry work

The paper presents the study carried out in a peri urban settlement of Nairobi Kenya and involved treatment of raw grey water generated from bathroom, kitchen and laundry for flushing toilet and laundry work. The study utilized both chemical and physical treatment. The chemical treatment involved alum addition in the raw grey water and pH adjustment using bicarbonate salts. The physical treatment involved filtration using Quartz sand and filtration of pH adjusted treated grey water using filter paper. The major ions studied were ions which could interfere with lathering of soaps or could cause stains on clothes and toilet fixtures or could be potentially health hazardous. These ions were Fe, Mn, Ca, Mg, Pb and Hg. The levels of these ions in raw grey water and in treated grey water were determined using atomic absorption spectroscopy. The results for the levels of these ions before treatment were compared to the set standards for potable water by Kenya Bureau of Standards [1]. The levels of these ions in the treated grey water after adjusting the pH were found to be within the Maximum Contaminant Limits (MCL) set by KEBS [1]. Thus the overall treatment of the raw grey water produced water of good quality which complied with the set standards for potable water by KEBS [1]. The results of this treatment could contribute immensely in the fulfillment of the millennium development goals.

Aas determination of aluminium levels in tea and other plants grown in the same locality

Abstract Total concentration of aluminium in leaves, stem, and roots of tea plant from various places was determined and compared to that in other plants grown in the same locality. Results showed that tea plant accumulated more aluminium than most other plants grown in the same locality with older leaves accumulating most of the aluminium in the range of 1350–2100μg/g. Grains were found to contain very little aluminium and in most cases it was not detectable. Leafy vegetables accumulated significant amounts of aluminium ranging from 200–650μg/g. Accumulation of aluminium in most plants was in the order of aluminium in leaves > aluminium in the roots > aluminium in stem.

Tropical surface water quality studies: Implications for the aquatic fate of N-methyl carbamate pesticides

ABSTRACT Water quality assessment was conducted on the Ruiru River, a tributary of an important tropical river system in Kenya, to determine baseline river conditions for studies on the aquatic fate of N-methyl carbamate (NMC) pesticides. Measurements were taken at the end of the long rainy season in early June 2013. Concentrations of copper (0.21–1.51 ppm), nitrates (2.28–4.89 ppm) and phosphates (0.01–0.50 ppm) were detected at higher values than in uncontaminated waters, and attributed to surface runoff from agricultural activity in the surrounding area. Concentrations of dissolved oxygen (8–10 ppm), ammonia (0.02–0.22 ppm) and phenols (0.19–0.83 ppm) were found to lie within normal ranges. The Ruiru River was found to be slightly basic (pH 7.08–7.70) with a temperature of 17.8–21.2°C. The half-life values for hydrolysis of three NMC pesticides (carbofuran, carbaryl and propoxur) used in the area were measured under laboratory conditions, revealing that rates of decay were influenced by the electronic nature of the NMCs. The hydrolysis half-lives at pH 9 and 18°C decreased in the order carbofuran (57.8 h) > propoxur (38.5 h) > carbaryl (19.3 h). In general, a decrease in the electron density of the NMC aromatic ring increases the acidity of the N-bound proton removed in the rate-limiting step of the hydrolysis mechanism. Our results are consistent with this prediction, and the most electron-poor NMC (carbaryl) hydrolyzed fastest, while the most electron-rich NMC (carbofuran) hydrolyzed slowest. Results from this study should provide baseline data for future studies on NMC pesticide chemical fate in the Ruiru River and similar tropical water systems.

Essential Antioxidant Elements in Oils of the Cake and Shell of Calodendrum capense Nuts

Abstract Increasing deaths due to skin cancer have been attributed to the sun’s ultra-violet (UV) radiations which initiate free radical reactions. Synthetic sunscreens contain antioxidants that prevent the free radical effects but risk skin exposure to harmful synthetic compounds of Cu, Mg, Mn and Zn. Calodendrum capense nut oil (cape chestnut or yangu oil), popular for African skin care is destined for natural cosmetic. Literature is scarce on the antioxidant element composition of its oil. We report the levels of Cu, Mg, Mn and Zn in oil from two parts of the nuts; cake and shells measured by AAS. Results show the potential supply of Cu, Mg, Mn and Zn from yangu oil of the two parts of the nuts that can serve as a physical sun-block. The use of yangu oil for skin protection against UV radiations is encouraged.