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Measuring Relative Toxicity and Assessing Risk
Published in Ronald Scott, of Industrial Hygiene, 2018
The general public often believes that any exposure, however small, to a substance characterized as toxic is lethal. The body can tolerate exposure to toxic substances, as long as the level is reasonable. This has always been necessary to human survival, since contact with toxicants is unavoidable. Plant materials in our diet, for example, contain a variety of substances that are consumed along with the protein, starch, lipids, vitamins, and minerals that constitute nourishment. Many of these substances would seriously threaten health if taken in large quantities. After all, the chemistry of the plant serves the needs of the plant, not those who plan to kill and eat it. Some plant species produce toxic substances as an aspect of survival; for example, locoweed produces a compound neurotoxic to grazing animals. Safe food need not be completely free of toxicants — such food may not exist. It is necessary only that the toxicants are at a low enough level that they clear from the body and problems they caused are repaired before the person takes in any more such toxicants. Toxicologists determine what levels of exposure are safe for the target population, those who are exposed, then set standards to ensure that these levels are not exceeded.
Core Eudicots: Dicotyledons IV
Published in Donald H. Les, Aquatic Dicotyledons of North America, 2017
Use by wildlife: The foliage of some Astragalus species is toxic and can cause locoism or reproductive dysfunction in livestock that graze on it (hence the common name of “locoweed” often is applied to this genus). Astragalus leptaleus is grazed by cattle (Mammalia: Bovidae: Bos taurus). The foliage of A. pycnostachyus is grazed by milk snails (Mollusca: Gastropoda: Helicidae: Otala lactea) and by mammals (Mammalia), including rabbits (Leporidae) and small rodents (Rodentia) such as gophers (Geomyidae), ground squirrels (Sciuridae: Spermophilus), and meadow voles (Cricetidae: Microtus). Astragalus pycnostchyus is also fed on by aphids (Insecta: Hemiptera: Aphididae). Senescing leaves of A. pycnostachyus are susceptible to attack by a sooty fungus (Fungi: Ascomycota). The seeds of A. pycnostachyus often are infested with seed beetles (Insecta: Coleoptera: Bruchidae), which can seriously reduce plant fecundity.
Ecotoxicity of 2,4-dinitrotoluene to cold tolerant plant species in a sub-Arctic soil
Published in International Journal of Phytoremediation, 2019
Stacey J. Doherty, Komi S. Messan, Ryan R. Busby, Robyn A. Barbato
We investigated the response of the Arctic plant species white spruce, field locoweed, bluejoint grass, and Jacob’s ladder to six concentrations of 2,4-dinitrotoluene (2,4-DNT) incubated at 22 °C and 12 °C. Plant toxicity determinations were performed by measuring the seedling emergence, fresh shoot mass, and dry shoot mass following exposure to a range of 2,4-DNT concentrations with the goal of obtaining models that describe each plant’s median effective concentration. Plant emergence and shoot growth were determined at the end of the incubation. Visual inspection revealed that the white spruce (Figure S1), field locoweed (Figure S2), bluejoint grass (Figure S3), and Jacob’s ladder (Figure S4) shoots were smaller with increasing concentrations of 2,4-DNT. Additionally, Jacob’s ladder exhibited larger leaf growth at 12 °C when compared to 22 °C, clearly demonstrating its preference for colder temperatures (Figure S4).