Quantitative modelling of Ostracod bioassay: assigning toxicity index to potentially chemical contaminated swimming pools.

One of the primary objectives of any public health programme is to design a protocol that will curtail a population from being predisposed to toxic substances in the environment. Biomarkers help in actualising such an objective by their potential to detect the presence of toxic substances in environmental media such as soil, water and air. The Ostracod Heterocypris incongruens, an already established biomarker for quality evaluation of freshwater, does not quantify toxicity. This work was aimed at modelling Ostracod bioassay as a quantitative whole-water toxicity assay (QWTA) for the determination of potentially chemical contaminated swimming pools. In this modelling approach, a pool water sample was deliberately contaminated with a mixture of Fenton reagent (FR) and Bonny light (BL) crude oil. The mechanism of toxic injury of this mixture is via oxidative stress-mediated superoxide ion and other free radicals. The mortalities and growth factors of the exposed freshly hatched Ostracods to the serial dilutions of the contaminated swimming pool water sample for 6 days were mathematically modelled to toxicity indices (Ti), which were used to construct the toxicity reference curve (TRC). A graph of the "toxic concentrations" of the serially diluted contaminated pool water sample against Ostracod mortality was plotted. The TRC and the linear graph constitute the "Ostracod-linked mathematical model". Against the reference mortality ≤ 20% of the Ostracods, the toxicity index based on the model prediction is ≤ 32.5, and this signifies "no observed toxic effect" for toxicity values below 32.5 units. Using this model, toxicity indices were calculated for 5 randomly selected swimming pools in the study area. The results showed that the outdoor pool SP 5 has a toxic index of 49.0, while outdoor pools SP 2 and SP 3 each has a toxic index of 42.5. The indoor swimming pool (SP 4) and Standard water (control) have zero toxicity, thus suggesting that that the outdoor pools SP 2, SP 3 and SP 5 were possibly contaminated by chemicals from extraneous sources while contamination of SP 1 was very much negligible, hence the "no observed toxic effect".

Evaluation of Pb concentrations in selected vegetables and portable drinking water, and intelligent quotients of school children in Ishiagu-a Pb mining community: health risk assessment using predictive modelling.

This study evaluates the concentrations of lead (Pb) in 6 selected vegetables and drinking water samples taken from an agricultural/mining town Ishiagu. This evaluation is important because these vegetables and water are major gateway of lead exposure through ingestion, especially children in the Pb mining environment. Pb at even very low concentrations has been shown to have adverse effect on developing brain and hence children's intellectual ability. The impact of lead-contaminated food/water intake on the cognitive function was focused on school children whose parents have lived in the Pb mining town for over 25 years before they were born. Non-invasive, "target risk quotient" (TRQ) methodology, based on the principle of predictive toxicology was adopted for our analysis. Samples of these vegetables harvested in July and August 2015, and water taken from homes at 4 different villages in Ishiagu town and neighbouring community Akaeze (control), were subjected to appropriate chemical treatment/digestion procedures and the concentrations of Pb determined using AA-700 Shimadzu model atomic absorption spectrophotometer. From 642 structured questionnaire administered to the teachers/children, the daily vegetable ingestion rates for each vegetable (mg/child/day) and estimated daily intakes (EDI) of lead were obtained. The results show that the concentrations of Pb in water samples and the 6 vegetables harvested from the lead mining town vary as distances increase from the mining sites while the total target hazard quotients (TTHQs) for the vegetable crops were greater than one (˃ 1). The cognitive functions of 160 school children (aged 6-8 years), sampled from 265 families based on their meeting the criteria for distances away from the mining site, were evaluated using Raven's Standard Progressive Matrices and psychometrics. The data generated were analysed using (SPSS) version 21.0 and results expressed as mean ± standard deviation of intelligent quotient (IQ). Students' t tests for independent samples were used to compare the IQ results for children in the lead mining area and non-mining area. A model based on predictive toxicology paradigm which can show a relationship between concentrations of lead in vegetables/water and cognitive function was developed. This model shows that there is a positive correlation between total lead concentrations in vegetables/water and children's cognitive function.

Health Implications of Occupational Exposure of Butchers to Emissions from Burning Tyres.

BACKGROUND: Flames from burning scrap tyres are used in de-furring animals for human consumption in most parts of Nigeria. Emissions from tyres are known to contain a myriad of toxic mixtures especially particulate matter (PM), volatile organic compounds, hazardous air pollutants, and inspirable metals, some of which are known human carcinogens. This cross-sectional study investigated the deleterious health effects of these emissions in occupationally-exposed workers at the Dei-Dei Abattoir, Abuja, Nigeria. METHODS: A total of 156 respondents were divided into two groups. Group 1 (124 butchers) and group 2 [32 administrative staff (AS)]. Data from digital spirometry were used to determine the association between chronic exposure to tyre emissions and lung function. Urinary 1-Hydroxypyrene concentration, phenolic compounds levels and heavy metal concentrations were determined. Also ambient PM and polycyclic aromatic hydrocarbons (PAHs) concentrations at 3 delineated points in the abattoir were measured. FINDINGS: Spirometry results showed significant deterioration of lung function in the butchers. The concentration of 1-Hydroxypyrene (µg/molCret) in the post-shift urine samples of the butchers was significantly higher (P < 0.05) in butchers relative to the AS (0.52 ± 0.13 Vs 0.20 ± 0.07, respectively). Similarly the concentrations of zinc and nickel (mg/l) were significantly higher in the butchers compared to the AS (zinc: 0.91 ± 0.19 Vs 0.31 ± 0.28, respectively; nickel: 0.11 ± 0.06 Vs 0.06 ± 0.02, respectively). Anthracene, fluoranthene, pyrene, benzo-a- pyrene, and PM concentrations were significantly higher at the de-furring point when compared to the wash bay and the administrative building, especially between 8.00 and 8.30 am. CONCLUSION: Occupational exposure to scrap tyre emissions resulted in significant adverse health effects. The existing laws banning the use of burning tyres in meat processing should be enforced while the use of personal protective equipment should be encouraged in abattoirs.

Biotechnological tools for environmental sustainability: prospects and challenges for environments in Nigeria-a standard review.

The environment is a very important component necessary for the existence of both man and other biotic organisms. The degree of sustainability of the physical environment is an index of the survival and well-being of the entire components in it. Additionally, it is not sufficient to try disposing toxic/deleterious substances with any known method. The best method of sustaining the environment is such that returns back all the components (wastes) in a recyclable way so that the waste becomes useful and helps the biotic and abiotic relationship to maintain an aesthetic and healthy equilibrium that characterizes an ideal environment. In this study, the method investigated includes biological method of environmental sustainability which seeks to investigate the various biotechnological tools (biotools) in current use and those undergoing investigations for future use.

Environmental pollution levels of lead and zinc in Ishiagu and Uburu communities of Ebonyi State, Nigeria.

Water and soil samples from the area were therefore analyzed for their lead and zinc content. Computation of pollution statuses of lead and zinc revealed topsoil lead geoaccumulation indices of -0.143 and -0.069 and zinc geoaccumulation indices of 1.168 and 0.713 for Ishiagu and Uburu respectively. The pollution indices were determined to be 0.499 and 0.3564 for soil in Ishiagu and Uburu respectively and also 5.11 and 2.42 for water in Ishiagu and Uburu communities respectively. Water/soil concentration ratio were found to be 0.0018 and 0.0014 for lead in Ishiagu and Uburu respectively. On the other hand, the water/soil concentration ratio for zinc was computed to be 0.001 and 0.0008 for Ishiagu and Uburu respectively. These results seem to suggest that the pollution of the environment by these heavy metals in the areas were as a result of the water being contaminated by lead and zinc not necessarily their concentrations in the soil.

Quantitative modelling of crude oil toxicity using the approach of cybernetics and structured mechanisms of microbial processes.

Cybernetics and structured approach to biochemical processes in microbial cells offer the status of using various cell components of Azotobacter as molecular markers in toxicity assay of environmental toxicants. The intra-linked dynamic physicochemical reactions of the basic macromolecules--DNA, protein and membrane lipids--with respect to the crude oil in the growth environment, results in an 'impulse transfer function'. The structured effects are reduction in both DNA and protein levels, and an elevated level of lipid peroxidation products. Toxicity index (Ti) of the crude oil, at a given concentration, is the percent ratio of the summation of the products of these effect parameters' and their respective weightings, relative to control. The EC50 is the effective percent (w/v) concentration of the crude oil at which a toxicity index of 50% was recorded, and this corresponded with about 44% loss in nitrogen fixation of the diazotrophic bacterium.