Selective bioaccumulation, biomagnification, and dissipation of hexachlorocyclohexane isomers in a freshwater food chain

Current perspective on veterinary drug and chemical residues in food of animal origin

The marked increase in the demand for animal protein of high quality necessitates protecting animals from infectious diseases. This requires increasing the use of veterinary therapeutics. The overuse and misuse of veterinary products can cause a risk to human health either as short-term or long-term health problems. However, the biggest problem is the emergence of resistant strains of bacteria or parasites. This is in addition to economic losses due to the discarding of polluted milk or condemnation of affected carcasses. This paper discusses three key points: possible sources of drug and chemical residues, human health problems, and the possible method of control and prevention of veterinary drug residues in animal products.

A critical review on the formation, fate and degradation of the persistent organic pollutant hexachlorocyclohexane in water systems and waste streams

The environmental impacts of persistent organic pollutants (POPs) is an increasingly prominent topic in the scientific community. POPs are stable chemicals that are accumulated in living beings and can act as endocrine disruptors or carcinogens on prolonged exposure. Although efforts have been taken to minimize or ban the use of certain POPs, their use is still widespread due to their importance in several industries. As a result, it is imperative that POPs in the ecosystem are degraded efficiently and safely in order to avoid long-lasting environmental damage. This review focuses on the degradation techniques of hexachlorocyclohexane (HCH), a pollutant that has strong adverse effects on a variety of organisms. Different technologies such as adsorption, bioremediation and advanced oxidation process have been critically analyzed in this study. All 3 techniques have exhibited near complete removal of HCH under ideal conditions, and the median removal efficiency values for adsorption, bioremediation and advanced oxidation process were found to be 80%, 93% and 82% respectively. However, it must be noted that there is no ideal HCH removal technique and the selection of removal method depends on several factors. Furthermore, the fates of HCH in the environment and challenges faced by HCH degradation have also been explained in this study. The future scope for research in this field has also received attention.

An innovative in vitro assay to study the effects of aromatic pollutants on porphyrin systems

Interactions between aromatic pollutants (APs) and porphyrin nucleus as physiological receptors have a significant effect on biological functions of porphyrin-based systems in organism. However, the details on the interaction at molecule level are still elusive. Herein, interaction mechanisms between two typical APs (methylene blue, MB and benzo[a]pyrene, B[a]P) and meso-tetra (4-carboxyphenyl) porphine (TCPP) as physiological receptors were systematically investigated. Adsorption behaviors of TCPP to B[a]P was dominated by pi-pi interaction, while interaction between TCPP and MB coupled with a multi-force field including hydrophobic, pi-pi, electrostatic, and H-bonding interactions. The relative contributions of these four forces obeyed an order: H-bonding > pi-pi > electrostatic > hydrophobic, regardless of the pH value and the initial concentration of MB. H-bonding assisted by hydrogen/hydroxide ion was the most influential force. According to the effect of pH and temperature, organisms exposed to cellular environment with high alkalinity and high temperature might uptake more APs molecules with chemical properties similar to MB and suffered greater health risks. In detail, APs might replace amino acid molecules surrounding porphyrin and change the distortion type of porphyrin molecule, and then affect biological functions of porphyrin and related proteins. This study facilitates a better understanding of potential toxicity of organisms in contaminated environment.

Potential Human Health Risks of Organochlorine Pesticides (OCPs) and Polychlorinated Biphenyls (PCBs) Associated with Fish Consumption in Anhui Province, China

In this study, the concentrations of 14 types of organochlorine pesticides (OCPs) and 7 types of polychlorinated biphenyls (PCBs) in four freshwater fish species (Ctenopharyngodon idella, Cyprinus carpio, Hypophthalmichthys molitrix and Hypophthalmichthys nobilis) collected from nine lakes in Anhui Province were determined. Among these contaminants, only hexachlorobenzene (HCB), heptachlor, hexachlorocyclohexane (β- and γ-HCH), dichlorodiphenyldichloroethylene (p,p'-DDE) and PCB 101 were detected, and HCB had the highest measured concentrations while the heptachlor showed the lowest concentrations. In the four fish species, C. carpio preferred to accumulate more OCPs and PCBs than C. idellus. Moreover, the health risk assessments demonstrated that consumption of these fish species may pose both non-carcinogenic and carcinogenic risks, especially for children at high exposure level (95th). As the concentrations of contaminants in ventral muscle were higher than that in dorsal muscle, the consumption of ventral muscle should be limited to avoid the potential risk of OCPs and PCBs.