Evaluation of the concentration of toxic metals in cosmetic products in Nigeria

It has been shown that heavy metals toxicity to humans is as a result of long term or high level exposure to pollutants common in the environment including the air, water, food and numerous consumer products such as the cosmetics and toiletries. In this study, we assessed the levels of toxic metals in different cosmetic products sold at local shops in Lagos, Nigeria. The cosmetic items included thirty creams and twenty lipsticks and lip glosses. These items were purchased from various shops at different locations in Lagos. The cosmetics were analyzed for heavy metals (arsenic, cadmium, lead, mercury and nickel) after digestion with concentrated acids HNO3: H2SO4: HClO4 in ratio 2:2:1. The concentrations of the selected toxic heavy metals were determined in duplicate using a Buck 205 flame atomic absorption spectrophotometer. All the samples analyzed contained a detectable amount of all the metals of interest. The concentration of the heavy metals in the samples ranged from 0.006 to 0.207 ppm. It is obvious from the present study that the use of some cosmetic products exposes users to low concentrations of toxic heavy metals which could constitute potential health risk to users since it has been known that heavy metals can accumulate in the biological system over time and are known to induce skin problems or diseases such as cancer. Further research to better understand the sources of heavy metals in cosmetic products is recommended.Key words: Toxic heavy metals, cosmetics, atomic absorption spectrophotometer, environment

Predictive ability of boiler production models

The weekly body weight measurements of a growing strain of Ross broiler were used to compare the of ability of three mathematical models (the multi, linear, quadratic and Exponential) to predict 8 week body weight from early body measurements at weeks I, II, III, IV, V, VI and VII. The results suggest that the three models fitted the 8th week body weight records at the seventh-week body measurement closely, judging from their respective R2-values (linear, 0.58; quadratic, 0.58 and exponential, 0.57). However, their ability to predict 8th-week body weight from early records using R2-value, varied generally from 0.15 + 0.36 to 0.58 + 0.23 for all the models. The predictions of 8th-week body weights based on fit to 7th-week data were more accurate for the linear and quadratic models, though all the models predicted less than the actual 8th-week records (-32, -35 and -38.14%) for linear, quadratic and exponential respectively. It could be concluded that based on the goodness of fit to 7th week body measurements record accuracy to predict 8th-week body weight from early record, the linear model gave the best result followed by the quadratic and exponential respectively. It could therefore be said that the models have graded theoretical advantage. This may be found useful in decision making concerning replacement of broiler chicken.Keywords: Poultry, broiler production, modeling, predictive abilit

Probability density fittings of corrosion test-data: Implications on C6H15NO3 effectiveness on concrete steel-rebar corrosion

In this study, corrosion test-data of steel-rebar in concrete were subjected to the fittings of the Normal, Gumbel and the Weibull probability distribution functions. This was done to investigate the suitability of the results of the fitted test-data, by these distributions, for modelling the effectiveness of C6H15NO3, triethanolamine (TEA), admixtures on the corrosion of steel-rebar in concrete in NaCl and in H2SO4 test-media. For this, six different concentrations of TEA were admixed in replicates of steel-reinforced concrete samples which were immersed in the saline/marine and the microbial/industrial simulating test-environments for seventy-five days. From these, distribution fittings of the non-destructive electrochemical measurements were subjected to the Kolmogorov-Smirnov goodness-of-fit statistics and to the analyses of variance modelling for studying test-data compatibility to the fittings and testing significance. Although all fittings of test-data followed similar trends of significant testing, the fittings of the corrosion rate test data followed the Weibull more than the Normal and the Gumbel distribution fittings, thus supporting use of the Weibull fittings for modelling effectiveness. The effectiveness models on rebar corrosion, based on these, identified 0.083% TEA with optimal inhibition efficiency, η = 72.17± 10.68%, in NaCl medium while 0.667% TEA was the only admixture with positive effectiveness, η = 56.45±15.85%, in H2SO4 medium. These results bear implications on the concentrations of TEA for effective corrosion protection of concrete steel-rebar in saline/marine and in industrial/microbial environments. © 2014 Indian Academy of Sciences