Dermatologic Toxicities and Biological Activities of Chromium

Chromium is a versatile metal with various industrial applications and biological activities. However, as a transition metal, this element forms several species, i.e. oxidation states of −4 to +6, with different degrees of toxicities that affect ecosystems and organisms including human beings. The skin is the outermost organ that usually interacts directly with chromium species in nature. These contact and interaction induce the formation of several acute and chronic negative effects including contact dermatitis, skin cancer, allergy, etc. In this chapter, toxicity and biological activity of several chromium species, such as chromium zero-valent, trivalent, hexavalent, will be reviewed to obtain better comprehension in chromium toxicity. Sources and routes of exposure, toxicity and possible treatment, and biological activity on the skin are arranged and explained systematically.

Sniffer Worm, C. elegans, as a Toxicity Evaluation Model Organism with Sensing and Locomotion Abilities

The probability of objects fabricated by three-dimensional (3D) printing exhibiting local defects is higher than that detected in products of conventional casting-based manufacturing. Multistep layer-by-layer procedures in additive manufacturing are the main reason. Light intensity and/or penetration depth, inhomogeneity of components, and variations in nozzle temperature are factors that create local defects. Defect regions are sources of toxic component release, but methods to identify them in printed materials have not been reported. Existing assays for evaluating material toxicity are based on extraction, and these toxicological assays use living creatures to passively detect harmful agents in extracted solutions. Thus, the development of an active system for identifying sites of toxicity sources is a critical and urgent issue in 3D printing technologies. Herein, we introduce an animal model system, C. elegans, for toxicity evaluation. C. elegans crawls toward safe regions but avoids toxically dangerous areas. The ‘sensing’ and ‘locomotion’ abilities of C. elegans are unparalleled among existing underwater and animal models, providing immediate indications to help find toxicity source sites.

Drilling Waste Control

The chapter describes drilling waste control by integrating Environmental Control Technology (ECT) with the drilling process. In contrast to remediating “end-of-the-pipe” methods, drilling ECT prevents environmental impact by modifying the process of drilling waste generation. The waste production process in drilling operations with emphasis given to mechanisms of waste volume buildup and the waste toxicity sources is analyzed. In addition, the source-reduction and source-separation techniques built-in the drilling process such as low-toxicity substitution of drilling mud components and high efficiency separators and closed-loop solids control mud system are addressed. The technique of drilling mud dewatering is discussed in detail by describing its principles, installations, and field application case histories. Quantitative analysis of dewatering efficiency using mud-testing results is also presented. The chapter also presents a method for assessing economic and technical feasibility of a dewatering service contracted for the well site.