R. Larry Grayson

Eco-toxicological and epidemiological assessment of human exposure to polycyclic aromatic hydrocarbons in the Niger Delta, Nigeria

Epidemiological examinations of polycyclic aromatic hydrocarbons (PAHs) exposure in biological bodies have shown the potential risk of cancer induction. Environmental media containing PAHs were analyzed in the Niger Delta region. Gas chromatographicmass spectrometric analyses were carried out on samples and 98% of the samples contained carcinogenic PAHs. The concentration of the 7 potential carcinogenic PAHs (Σcarcsoil 7PAHs) in the soils varied from 297–4080.6±546.3 mg/kg (min-max +/- standard deviation) with a median of 419 mg/kg, the concentrations for non-carcinogenic PAHs ranged from 315–1999±300 mg/kg with a median of 497.5 mg/kg. The total concentrations of PAHs (»total H2O17PAHs) in water samples varied from 119.8–450.0±117.9 mg/L with a median of 141.9 mg/L, while the sediment concentrations ranged from 6.0–132.0±28.7 mg/L with a median of 62.73 mg/L. Concentrations of benzo(a) pyrene (BaP), which most likely originated from crude oil spillage in the area was determined as 66.95±73.47 mg/kg in soil samples. To evaluate human exposure to carcinogenic PAHs sources, the toxic equivalence factors (TEFs), mutagenic potency equivalent factors (MEFs) and the incremental lifetime cancer risk (ILCR) methodologies were used to calculate the exposure risk. Carcinogenic equivalents (BaP-TEQ) and mutagenic equivalents (BaP-MEQ) were calculated from the potency relative to BaP (TEF) and BAP (MEF) respectively. BaP-TEQ (mg/kg) for Ωcarcsoil 7PAHs were determined as 98.80±125.81 and varied from 68.20–953.84 mg/kg, while the BaPMEQ (mg/kg) for Σcarcsoil 7PAHs were determined as 124.01±163.37 and varied from 87.24–1237.82 mg/ kg. The BaP-TEQ (mg/kg) for ΩcarcH2O7PAHs were determined as 16.79±14.44 and varied from 5.55–52.69 mg/L, similarly the BaP-MEQ (mg/kg) for ΩcarcH2O 7PAHs were determined as 9.29±8.15 and varied from 1.55–29.80 mg/kg. The cumulative ILCR from the water and soil contaminations were determined as 1.13×10−4 and 6.42×10−4 respectively for children, while values of 1.09×10−4 and 6.19×10−4 were determined respectively for adult. The ecotoxicological assessments in this study indicate contamination of environmental media in the region with high potential of acute toxicity sufficient enough to induce carcinogenic effects and chronically affect the human health of residents with prolonged exposures.

Surface Properties of Respirable Silicate and Aluminosilicate Dusts Affecting Bioavailability

Pure respirable quartz is a known pathogenic agent for lung disease. However, for mixed dusts, neither mineralogical nor, in vitro, cytotoxicity assays unequivocally predict the contribution of quartz to their pathogenic potential.

Microanalysis of Roof Bolter Injuries

Abstract The purpose of this article is to demonstrate the method and value of microanalysis through its application to reported personal injuries to roof bolters. The technique involves analysis of accident narratives in order to classify the reported injuries according to where they occurred in the roof bolters work cycle. Microanalysis allows an investigator to use the narrative descriptions to frame the conditions and situations under which miners were injured, results which then may be used in annual refresher training to make breakout sessions site and job specific. A combination of microanalysis and work-site observations of roof bolters was used in this study to classify accidents into selected work routines, to calculate new accident indices, to characterize the situations and conditions surrounding the accidents, and to describe the causes of many of the accidents in work-related terms.

Dynamic programming solution for the optimal allocation of mine manpower to multiple work activities

Abstract A dynamic programming model is formulated and applied to allocate coal miners among work activities optimally on an operating shift basis. The recurrence relation used maximizes the revenues obtained by allocating miners to separate but competing work activities.

Safety and productivity in coal mining—How to make both the top priority

Abstract Focusing on coal mine safety and productivity in the United States as well as the relationship that exists between them, this chapter first briefly describes the evolution of each prior to and subsequent to the passage of the Coal Mine Health and Safety Act of 1969. The evolution of safety practices will be described over the same timeline. Finally, the coupling of management and labor policies, practices, and operational activities on safety and productivity, with both as top priorities, that will lead to a safe and responsible mining enterprise will be discussed. Likely future trends will be assessed as well.

A comparison of two instructional approaches in teaching underground rock bolt installation with a Jackleg Drill

An integrated hypermedia training tool on underground rock bolting was evaluated using qualitative and quantitative methodologies to compare it with the traditional method of training underground rock bolters. Usability experiments performed underscore the need to evaluate a new product to ensure that it meets the requirements of users. Statistical results from comparative experiment indicate that a task must be sufficiently complex in order to render a traditional paper-based method less effective than a computer-based method. Additionally, participants in the computer-based group (n = 25) rated the training effectiveness more positively than those in the paper-based group (n = 25).