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Introduction to Basic Toxicology
Published in Armen S. Casparian, Gergely Sirokman, Ann O. Omollo, Rapid Review of Chemistry for the Life Sciences and Engineering, 2021
Armen S. Casparian, Gergely Sirokman, Ann O. Omollo
If a toxicant is a naturally occurring substance, it may more specifically be referred to as a toxin. Poison is a more common term for toxicant and refers to any substance that is toxic, whether natural or synthetic, regardless of any of the three, main exposure routes resulting in absorption: inhalation, ingestion, or dermal (or eye) contact. Dose (in bold print) is the amount of chemical entering the body. Absorption means the ability of the toxicant to enter the bloodstream at some point, though it may be first be absorbed into the lungs (inhalation), skin (dermal), or GI tract (ingestion). It is presumed that the blood is in equilibrium with the body’s tissue and cells. If a substance is toxic by involuntary injection, it is referred to as a venom. Some snake and spider bites are venomous. Intravenous (or IV) is a fourth, less common absorption route.
Approaching a closer surrogate for the biologically effective dose with subcellular partitioning-based toxicokinetic models
Published in Critical Reviews in Environmental Science and Technology, 2023
T. T. Yen Le, Olivier Geffard, Alain Geffard, Willie J. G. M. Peijnenburg
Toxicokinetics and toxicodynamics are complementary components of toxicology. Toxicokinetics describe the effects that an organism exerts on a toxicant, while toxicodynamics show the effects that the toxicant exerts on the organism. The former addresses absorption, distribution, metabolism (biotransformation), and excretion of the toxicant, whilst the latter refers to the interactions between the toxicant and its target sites, which trigger toxicity (Escher & Fenner, 2011). Ideally, the toxicokinetic phase in TK-TD models provides estimates of the concentration of the toxicant at sites of toxic action. However, in most of the available models, toxic effects are related to the total internal concentration, excluding the significance of subcellular metal sequestration (Ashauer et al., 2013; Feng et al., 2018; Gao et al., 2015).
Toxicity Reduction of Microcystis Aeruginosa Using Microbubble Ozonation
Published in Ozone: Science & Engineering, 2023
Gwiwoong Nam, Min-Seo Jeon, Yoon-E Choi, Jinho Jung
Acute toxicity of M. aeruginosa was conducted on D. magna in triplicate according to the OECD Guideline 202 (OECD (Organization for Economic Co-operation and Development) 2004). The ISO medium was used for testing and as a control. After adding M. aeruginosa in BG11 medium (10 mL) to the test medium (20 mL), each experiment was performed for 48 h using 10 neonates less than 24 h old. During the test, temperature and light period were maintained 20 ± 0.2 °C and 16:8 light and dark cycles. No food was given during the tests. Immobilization was defined as the species that did not react after 15s of gentle agitation. The results of the tests were not used when the immobility was above 10% in the control water (test medium). Median effective concentration (EC50) was determined using the trimmed Spearman–Karber method (Hamilton, Russo, Thurston 1977). The quality of acute toxicity test was verified using a reference toxicant (K2Cr2O7).
Effects of short-term sub-lethal diazinon® exposure on behavioural patterns and respiratory function in Clarias batrachus: inferences for adaptive capacity in the wild
Published in Chemistry and Ecology, 2022
Shubhajit Saha, Azubuike V. Chukwuka, Dip Mukherjee, Kishore Dhara, Aina O. Adeogun, Nimai Chandra Saha
Safe limits assessment: The extent of tolerance exhibited by the test organism to a toxicant at different times of exposure is expressed as the toxicity factor (TF) [49,50]. In this study, Toxicity factor values of C. batrachus to diazinon at median lethal concentrations (LC50) under 24, 48, 72 and 96 h were 1.00, 1.150, 1.353 and 1.697 respectively. The toxicity factor values climbed as the time of exposure progressed. Such has been attributed to differential uptake, rate of excretion or redistribution of the toxicant to less sensitive target sites [51]. The lowest value (0.129 mg/L) obtained in our study is the estimated possible safe level for diazinon that is conservative for C. batrachus (Table 2). The safe levels vary because of the usage of varied application factors (AFs) and their dependence on LC50 value [52]. Thus, it is controversial to practically accept any single value as MATC which is ‘safe’ for the toxicant to C. batrachus [53].