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Basic Chemical Hazards to Wildlife
Published in Jack Daugherty, Assessment of Chemical Exposures, 2020
Primary and secondary consumers and producers in an ecosystem form a food chain, or food web, in which organisms eat smaller organisms and are generally eaten in turn by larger organisms. Sometimes, rather than being larger in size, the higher organisms are simply more developed, or else more efficient at hunting or at eating than the eaten organism. Regardless, lower trophic levels are prey to predators of higher trophic levels. Several trophic levels may be identified in any ecosystem. Through these levels, bioaccumulation or biomagnification can occur. When increasingly higher concentrations of a toxic substance are passed up the food chain it is biomagnification. Bioaccumulation refers to the uptake of dissolved as well as ingested phases of a COC. The tissue of the receptor has a greater concentration of the COC than the environment. According to Landis and Yu, this occurs when the COC is more lipophilic than hydrophilic. Bioconcentration pertains to the accumulation of dissolved chemicals, nutrients or pollutants, in plants and animals creating potentially harmful exposures to higher trophic levels. When metabolism breaks down a COC into materials with reduced or altered toxicity, that is biotransformation. Biodegradation is any process that breaks down COCs into simpler, often less hazardous forms.
Introduction
Published in Michael J. Kennish, Ecology of Estuaries: Anthropogenic Effects, 2019
The bioaccumulation of pollutants in the tissues of aquatic organisms is particularly important because it has been widely used to delineate the degree of contamination of estuarine waters. Toxicologists often employ the terms “bioconcentration” and “biomagnification” when describing bioaccumulation. Bioconcentration refers to an organism’s ability to accumulate a contaminant significantly in excess of that in the ambient water. Biomagnification, in turn, is the concentration of a pollutant up the food chain such that relatively low levels accumulate in organisms at the base of the chain and higher levels, possibly reaching harmful or lethal doses, in organisms at the to of the chain.20 While certain substances may consistently exhibit a bioconcentration effect in biota, they do not necessarily biomagnify up the food chain. Manee21 has shown this to be the case among heavy metals.
Necessity for Effective Programming Techniques
Published in Herman Koren, Best Practices for Environmental Health, 2017
Past exposure may have resulted in tissue damage or heightened the susceptibility of the individual to disease processes from the contaminant which has been retained in the human body or the damage done by previous exposures. The length of time of the exposures and the concentration of the exposures are very important. The exposures may be through inhaled air, ingestion of water and food, absorption through the skin, or a combination of these routes of entry into the body. Bioconcentration of chemicals may occur in the food chain when a higher form of life consumes a contaminated lower form of life, and then this food source may cause disease when ingested by people. Further, multiple contaminants may interact with each other to become more toxic to the individual. The human body may alter the contaminants and make them more toxic during the metabolic process. The liver and kidneys become special potential problem areas when the substances are processed and secreted.
Controlling factors and toxicokinetic modeling of antibiotics bioaccumulation in aquatic organisms: A review
Published in Critical Reviews in Environmental Science and Technology, 2023
Minghua Zhu, Jingwen Chen, Willie J. G. M. Peijnenburg, Huaijun Xie, Zhongyu Wang, Shuying Zhang
Bioconcentration in aquatic organisms involves uptake of chemicals from water alone, which may occur through the respiratory surface and/or skin of the organisms (Mackay & Fraser, 2000). BCF (L/kg) is defined as the ratio of the chemical concentration in an organism (CO, ng/kg) and the concentration of the chemical in water (CW, ng/L) in equilibrium. However, the equilibrium state is challenging to achieve. Kinetically determined BCF, defined as the ratio of uptake rate constant (ku) and elimination rate constant (ke), is usually used instead. The ku and ke values are generally estimated by determining time-course internal concentration curves under controlled waterborne exposure conditions in laboratory according to standardized protocols such as OECD TG305 (OECD, 2012):
Trophic transfer, bioaccumulation, and biomagnification of non-essential hazardous heavy metals and metalloids in food chains/webs—Concepts and implications for wildlife and human health
Published in Human and Ecological Risk Assessment: An International Journal, 2019
Before going into the details of this section, it is time to clear the concepts of some important terms: trophic transfer, bioconcentration, dietary accumulation, bioaccumulation, biomagnification, and trophodynamics. These terms are described below and depicted in Figure 3. Trophic transfer (also called biotransference) refers to the passage of a contaminant in food chains, from one trophic level to the next.Bioconcentration refers to the accumulation of a contaminant in an organism as a result of its uptake from the ambient abiotic environment.Dietary accumulation refers to the accumulation of a contaminant in an organism as a result of its uptake from the organism's food/diet.Bioaccumulation refers to the accumulation of a contaminant in an organism as a result of its uptake from both the ambient abiotic environment and the organism's food/diet.Biomagnification refers to the increase in concentration of a contaminant along a food chain, that is, along successive trophic levels in a food chain.Biodilution refers to the decrease in concentration of a contaminant along a food chain.Trophodynamics refers to the study of trophic transfer of a chemical in food chains