Oluwole A. Agbede

Lead levels in new enamel household paints from Asia, Africa and South America.

In 2006 a report on the analysis for lead in 80 new residential paints from four countries in Asia revealed high levels in three of the countries (China, India and Malaysia) and low levels in a fourth country (Singapore) where a lead in paint regulation was enforced. The authors warned of the possible export of lead-painted consumer products to the United States and other countries and the dangers the lead paint represented to children in the countries where it was available for purchase. The need for a worldwide ban on the use of lead in paints was emphasized to prevent an increase in exposure and disease from this very preventable environmental source. Since the earlier paper almost 300 additional new paint samples have been collected from the four initial countries plus 8 additional countries, three from Asia, three from Africa and two from South America. During the intervening time period two million toys and other items imported into the United States were recalled because the lead content exceeded the United States standard. High lead paints were detected in all 12 countries. The average lead concentration by country ranged from 6988 (Singapore) to 31,960ppm (Ecuador). One multinational company sold high lead paint in one country through January 2007 but sold low lead paint later in 2007 indicating that a major change to cease adding lead to their paints had occurred. However, the finding that almost one-third of the samples would meet the new United States standard for new paint of 90ppm, suggests that the technology is already available in at least 11 of the 12 countries to produce low lead enamel paints for domestic use. The need remains urgent to establish effective worldwide controls to prevent the needless poisoning of millions of children from this preventable exposure.

An examination of knowledge, attitudes and practices related to lead exposure in South Western Nigeria

BackgroundLead is a highly toxic and pervasive metal. Chronic exposure to low levels is responsible for significant health effects, particularly in children. Prevention remains the best option for reducing childhood lead exposure, however the knowledge, attitudes and practices to lead exposure in many developing countries is not known.Methods: We conducted four focus group discussions (FGD) to evaluate knowledge attitudes and practices to lead exposure in Nigeria. An FGD guide was developed from the literature and preliminary discussion with members of the public. Participants in the FGD were randomly selected from adults living in Ibadan, South Western Nigeria in 2004.ResultsWe found that there was limited awareness of the sources of lead exposure in the domestic environment and participants had little knowledge of the health effects of chronic low-dose lead exposure.ConclusionWe conclude that the findings of this study should be used, in conjunction with others, to develop appropriate health education intervention for lead exposure in the domestic environment.

An Evaluation of Lead Levels in Paints for Residential Use Sold in the Nigerian Market

In developing countries, relatively, little or no attention has been devoted to the potential for childhood exposure to lead used in domestic paint. In this study, we measured lead levels in 19 samples of locally manufactured paint purchased from the Nigerian market in February, 2005. The level of lead in the paints ranged from 17.5μg·g−1 to 515.9μg·g−1, with mean (SD) of 62.2μg·g−1 (115.1μg·g−1), while the median was 25.1μg·g−1. We conclude that paints sold in Nigeria still contain a substantial amount of lead with increased risk of exposure to xchildren, for whom domestic sources of lead exposure is more important than exposure through leaded petrol. We advocate the future use of lead-free paint and lead abatement in order to reduce childhood lead exposure.

Electrochemical Soil Stabilization and Verification

ElectroChemical treatment (ECT) has been applied for the in situ chemical stabilization soft clay soils. A possibility during ECT is mineral dissolution and re-deposition which can cause micro-structural changes affecting the engineering behavior of clay soils. Additionally, during ECT the success of depositing the stabilizing chemicals in the tight clay matrices may be hindered by process parameters, such as electrode reactions. A simple monitoring method was tested in the laboratory to track the evolution of intended ECT stabilization for quick assessment and potential control of the process. Calcium and phosphate ions were injected separately and then together into kaolin clay under a constant voltage gradient at varying durations. Calcium hydroxide and phosphoric acid were used as the feed electrolytes in the anolyte and catholyte, respectively. The ECT triggered stabilization was diagnosed by monitoring the evolution of clay soil stiffness. The shear wave velocity (Vs) and the small strain modulus (Gmax) of the treated specimens were monitored using bender elements (i.e., piezoelectric transceivers). Finally, changes in the microstructure of the clay were analyzed using comparative XRD and SEM scans of pre- and post-treatment specimens. The analysis showed that electro-migration of calcium ions occurred but did not result in the expected cementation within the clay soil because of low pH hindering formation of calcium hydrates. In contrast, the Gmax of the samples treated with phosphate ions increased at the cathode and the middle sections of the clay specimens by 10 and 20%, respectively. While SEM results did not reveal discernible micro-structural changes in the treated clay matrix, the XRD result showed discernable changes in some elemental peaks, indicating chemical accumulation. The nondestructive diagnostic method was beneficial and showed promise for possible field application for transient assessment of the efficacy of ECT stabilization of clay soils.

Development of Predictive Model for Investigating Effect of Sodium Chloride on Soil Geotechnical Properties

The study centred on the development of predictive equations to determine soil contaminated with sodium chloride geotechnical properties at given level of cation exchange capacity (CEC), exchangeable anion and cation. Soil samples for the work were taking from two borrow pits in Ibadan, Nigeria. Aside the control, each sample was divided into sixteen and grouped into. Each group received a single dose of 10, 30, 50 and 70 g/dm3 and their geotechnical and chemical monitored for 365 days. The geotechnical properties obtained were used as dependent variables while chemical properties as independent variables in multiple regression model to generate fourteen equations for estimating soil geotechnical properties at specified levels of chemical properties. The results revealed that the two soils geotechnical properties except coefficient of permeability decrease with increase in salt concentrations and time. Also, the differences between the measured and predicted or simulated geotechnical properties were in the range of 10.08 and +6.51 %.