Miscellaneous poisons
Jason Payne-James, Richard Jones in Simpson's Forensic Medicine, 2019
When arsenic is detected in a post mortem tissue sample the significance of its presence is often difficult to determine. The presence of arsenic may indicate acute poisoning or it may indicate nothing at all. This predicament arises because arsenic exists in two forms: organic and inorganic. The term ‘organic’ indicates that the arsenic is bound to another organic molecule and unable to exert toxicity (the resultant compounds are called arsenosugars and arsenobetaine). In contrast, the term inorganic arsenic indicates that the arsenic atom exists as a salt bound to another cation; this salt may disassociate and then cause poisoning. The arsenic found in oysters from contaminated oyster beds is an example of organic arsenic, whereas the arsenic found in coal deposits is an example of the inorganic form. The standard method used to detect arsenic in post mortem materials does not differentiate organic from inorganic arsenic, so the mere detection of this compound has little significance, at least not without a very suggestive clinical history.
Animal Source Foods
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Besides mercury, arsenic is also found in seafood, in particular crustaceans like lobsters and crabs, and bivalves like clams, oysters, scallops, and mussels. Arsenic is a metalloid that occurs in different inorganic and organic forms, which are found in the environment both from natural occurrence and from anthropogenic activity. The mineral forms of arsenic are more toxic than the organic arsenic (37). In fish and crustaceans, the toxic mineral arsenic is transformed into soluble organic form named arsenobetaine, which becomes nontoxic and easily excreted via human urine (37). Other organic arsenic forms found in fish, shellfish, and marine algae are arsenocholine, arsenosugars, and arsenolipids, which are considered nontoxic (37).
An Introduction to Risk Assessment with a Nod to History
Ted W. Simon in Environmental Risk Assessment, 2019
A biomarker is physiological quantity measurable in humans in vivo. The best-known example is the alcohol breath test for sobriety. Because ethyl alcohol will volatilize from the blood to the air in the lungs, it can be measured in breath. Breath alcohol is not a direct measure of blood alcohol. Biomarkers can reflect either exposure or effect. The occurrence of arsenic in urine is a poor biomarker for chronic exposure to arsenic because it may reflect recent seafood consumption due to the prevalence of arsenobetaine in fish; arsenic in toenails, however, is considered more representative of long-term exposure.196
Co-exposure to nTiO2 impairs arsenic metabolism and affects antioxidant capacity in the marine shrimp Litopenaeus vannamei
Published in Drug and Chemical Toxicology, 2021
Lucas Cordeiro, Larissa Müller, Silvana Manske Nunes, Luiza Wilges Kist, Mauricio Reis Bogo, Caroline Pires Ruas, Marcos Gelesky, Wilson Wasielesky, Daniele Fattorini, Francesco Regoli, José Marìa Monserrat, Juliane Ventura-Lima
As can be found in different chemical variants; inorganic forms of As (iAs), such as arsenate and arsenite (AsV and AsIII, respectively), are predominant in aquatic environments, whereas organisms are shown to accumulate mostly organic As-containing compounds (Fattorini et al.2013). This accumulation of organic As compounds is related to the metabolic capacity of an organism when exposed to iAs. The process of As metabolism involves oxidation/reduction reactions, reduced glutathione (GSH) being used as an electron donor and enzymes such as the glutathione-S-transferase omega isoform (GSTΩ) considered the rate-limiting step in As metabolism (Thomas 2007). Marine organisms accumulate As mostly as arsenobetaine (AsB), arsenocholine (AsC), tetramethylarsenic (TETRA), and trimethylarsine oxide (TMAO), which are considered nontoxic (Vahter 2002). However, some organisms with a lower capacity for metabolism can also accumulate compounds considered moderately toxic, such as mono- and dimethyl arsenic (MMA and DMA, respectively).
Intravenous arsenic trioxide and all-trans retinoic acid as front-line therapy for low-risk acute promyelocytic leukemia
Published in Expert Review of Hematology, 2019
The first pharmacokinetic studies were performed in 8 relapsed APL patients through gas chromatography by measuring the plasma drug levels [15]. After a first plasma peak level of 6.85 µmol/L, the drug was rapidly eliminated, with a half-life elimination time of 0.89 h. The plasma levels of arsenic fluctuated between 0.1 and 0.5 mol. In the same study, possible changes of arsenic after its long-term administration were evaluated. The results showed that the continuous administration did not alter the plasma concentrations of the drug. High amounts of arsenic appeared in the urine in the same day of the infusion accounting for approximately 1–8% of the total daily dose administered. The urinary excretion of arsenic persisted after withdrawal of the drug, but with a decreased amount. Hair and nails contained traces of arsenic, which increased during administration (a peak of 2.5–2.7 µg/g) and declined after withdrawal of the drug. Mass spectrometry identifies several arsenic compounds such as sodium arsenite, sodium arsenate, sodium methylarsonate (MMAs), dimethyl-arsinic acid (DMAs), trimethylarsine oxide (TMAsO), arsenobetaine (AsBe), arsenocholine (AsCho) and tetramethyl-arsonium (TetMAs). DMAs and MMAs were detected in the serum and urine, and their concentrations increased after 2 h from completion of administration [16]. Au et al. [17] studied the arsenic levels in 67 paired cerebrospinal fluid (CSF) and plasma samples from 9 APL patients receiving oral ATO. The median levels in the CSF and plasma were 95.8 nmol/L (range 3.5–318.9 nmol/L) and 498.9 nmol/L (range 36.3–1892.8 nmol/L), respectively, with CSF levels being 17.7% of the plasma levels. The results suggested that arsenic was present in the CNS at therapeutic concentrations [17].
Related Knowledge Centers
- Arsenic
- Betaine
- Biosynthesis
- Choline
- Trimethylglycine
- Urea
- Trimethylarsine
- Median Lethal Dose