| plant growth substances | <plant biology> Substances that, at low concentration, influence plant growth and differentiation. Formerly referred to as plant hormones or phytohormones, these terms are now suspect because some aspects of the hormone concept, notably action at a distance from the site of synthesis, do not necessarily apply in plants. Also called plant growth regulators. The major classes are absicisic acid, auxin, cytokinin, ethylene and gibberellin, others include steroid and phenol derivatives. (31 Dec 1997) |
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| hazardous substances | Substances which, upon release into the atmosphere, water, or soil, or which, in direct contact with the skin, eyes, or mucous membranes, or as additives to food, cause health risks to humans or animals through absorption, inhalation, or ingestion. The concept includes safe handling, transportation, and storage of these substances. (12 Dec 1998) |
| thiobarbituric acid reactive substances | Low-molecular-weight end products, probably malondialdehyde, that are formed during the decomposition of lipid peroxidation products. These compounds react with thiobarbituric acid to form a fluorescent red adduct. (12 Dec 1998) |
| toxic substances | A chemical or mixture of chemicals that presents a high risk of injury to human health or to the environment. (05 Dec 1998) |
| acute organic brain syndrome | <syndrome> A constellation of behavioural or psychological signs and symptoms including problems with attention, concentration, memory, confusion, anxiety, and depression caused by transient or permanent dysfunction of the brain. Synonym: acute organic brain syndrome, OBS, organic mental syndrome. (05 Mar 2000) |
| volatile organic compounds | (VOC) Emissions of non-methane hydrocarbons, measured by standard DEQ methods. (05 Dec 1998) |
| substance-induced organic mental disorders | Mental disorders caused by use of drugs, e.g., cocaine. (05 Mar 2000) |
| organic | Any foods grown without the use of chemical fertilisers or pesticides, in soil made rich by composting and mulching. Pertaining to carbon-based compounds produced by living plants, animals or by synthetic processes. (27 Sep 1997) |
| organic acid | An acid made up of molecules containing organic radicals; e.g., acetic acid, citric acid, which contain the ionizable -COOH group. (05 Mar 2000) |
| organic brain syndrome | <syndrome> A constellation of behavioural or psychological signs and symptoms including problems with attention, concentration, memory, confusion, anxiety, and depression caused by transient or permanent dysfunction of the brain. Synonym: acute organic brain syndrome, OBS, organic mental syndrome. (05 Mar 2000) |
| organic catalyst | A catalyst that is an organic molecule. See: enzyme, ribozyme. (05 Mar 2000) |
| organic chemicals | A broad class of substances containing carbon and its derivatives. Many of these chemicals will frequently contain hydrogen with or without oxygen, nitrogen, sulfur, phosphorus, and other elements. They exist in either carbon chain or carbon ring form. (12 Dec 1998) |
| organic chemistry | <chemistry> A branch of chemistry that deals specifically with the structures, synthesis and reactions of carbon-containing compounds. (11 Jan 1998) |
| organic compound | <chemistry> A compound containing carbon. (11 Jan 1998) |
| organic contracture | Contracture, usually due to fibrosis within the muscle that persists whether the subject is conscious or unconscious. Synonym: fixed contracture. (05 Mar 2000) |