A handbook of environmental toxicology: human disorders and ecotoxicology最新文献

{"title":"Phytotoxins.","authors":"J. D'mello","doi":"10.1079/9781786394675.0003","DOIUrl":"https://doi.org/10.1079/9781786394675.0003","url":null,"abstract":"Abstract\u0000 Evidence of the existence of a wide range of secondary compounds and proteins in plants with pharmacological activity or with the potential to cause adverse effects in other living organisms is now firmly embedded in the scientific literature. The term 'phytotoxins' is conventionally used to describe these substances, but there are issues associated with nomenclature which are addressed below. In this chapter, the ecology of phytotoxins, including several glycosides, non-protein amino acids, furanocoumarins, condensed tannins, gossypol and specific anti-nutritional proteins, is considered. A number of these compounds occur exclusively in tropical plants while others are more universally distributed but with particular relevance in temperate environments. The aforementioned phytotoxins have been selected for diverse manifestations and implications in toxicology. Effects in mammals include digestive dysfunction caused by anti-nutritional proteins in legume seeds; irreversible spastic paralysis and cognition defects induced by cyanogenic glycosides in cassava; goitrogenic activity precipitated by Brassica glucosinolate breakdown products; favism associated with pyrimidine glycosides in faba beans; cardiotoxicity and reproductive abnormalities caused by gossypol in cottonseed; phytodermatitis following contact with furanocoumarins in celery and other plants; and cancer induced by ptaquiloside in bracken fern. Lower organisms possess variable mechanisms for metabolizing several of these phytotoxins. Nevertheless, it is consistently maintained that phytotoxins serve in a protective role in plants against invertebrate herbivores and fungal pathogens. It is concluded that a defence system based on protein phytotoxins may be relatively more robust than those involving secondary compounds. Furthermore, it is suggested that these heat-labile protein phytotoxins should form part of a plant breeding programme to enhance pest and pathogen resistance without compromising food safety. However, the challenge for the future is to exploit the wide array of the other phytotoxins as environmentally friendly protectants for food crops. Structure-activity and other functional relationships have been established for a limited number of phytotoxins, thus improving the prospects for the development of more effective bio-pesticides.","PeriodicalId":236595,"journal":{"name":"A handbook of environmental toxicology: human disorders and ecotoxicology","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125038273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cyanobacterial toxins.","authors":"J. Metcalf, N. R. Souza","doi":"10.1079/9781786394675.0033","DOIUrl":"https://doi.org/10.1079/9781786394675.0033","url":null,"abstract":"Abstract\u0000 Cyanobacteria are capable of producing a wide range of low-molecular-weight toxic compounds, largely identified as a result of poisoning incidents and through meticulous screening of cyanobacterial strains and blooms. Their molecular modes of action vary and can include hepatotoxic and neurotoxic effects in acute doses. Furthermore, long-term exposure to cyanobacterial toxins has been implicated in a number of human health conditions, from primary liver cancer to human neurodegenerative disease. Through various routes and media, exposure to cyanobacterial toxins can occur and toxicological and quantitative assessment of cyanobacterial blooms should be performed to help minimize adverse effects on human and animal health. Management and treatment of cyanobacterial blooms can, in the long term, prevent periodic exposure to these toxic compounds.","PeriodicalId":236595,"journal":{"name":"A handbook of environmental toxicology: human disorders and ecotoxicology","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117343912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lead poisoning.","authors":"A. Katner, H. Mielke","doi":"10.1079/9781786394675.0371","DOIUrl":"https://doi.org/10.1079/9781786394675.0371","url":null,"abstract":"Abstract\u0000 The reduction of childhood lead exposure in the USA is a public health success story, but lead is still one of the most widely encountered toxic metals in the world. To date, no safe blood lead threshold has been identified. The properties and availability of lead, a naturally occurring blue-grey heavy metal, led to its widespread use throughout history in paint, gasoline, plumbing, food containers and a vast array of other commercial products, which in turn led to a persistent legacy of widespread lead contamination. The toxic effects of lead were recognized as early as 2000 bc, but the mechanisms by which lead exerts it impacts have only been elucidated in the past few decades. This chapter discusses the historical use and regulation of lead and provides an overview of lead's toxicological mechanisms and health effects. Particular emphasis is placed on low-dose lead impacts, which are most relevant to developed countries that have seen a decline in population lead exposures due to regulation and exposure prevention efforts.","PeriodicalId":236595,"journal":{"name":"A handbook of environmental toxicology: human disorders and ecotoxicology","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133118572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mycotoxins.","authors":"J. D'mello","doi":"10.1079/9781786394675.0019","DOIUrl":"https://doi.org/10.1079/9781786394675.0019","url":null,"abstract":"Abstract\u0000 Mycotoxins induce adverse effects in humans and other vertebrate animals. Their production is determined by ecological and environmental factors (temperature, humidity and substrate water activity). The preponderance of specialized fungi in particular niches determines the type and range of mycotoxins that may contaminate food or indoor environment. Claviceps, Fusarium and Alternaria species are classical exponents of plant pathogens with toxigenic potential. C. purpurea produces the ergot alkaloids, while the principal Fusarium mycotoxins include the trichothecenes, zearalenone and fumonisins. A. alternata synthesizes tenuazonic acid, alternariol and altenuene. Aspergillus and Penicillium species exemplify food spoilage fungi, associated with particular conditions in post-harvest ecology. Aspergillus flavus and A. parasiticus produce the aflatoxins B1, B2, G1 and G2, but A. ochraceus together with Penicillium viridicatum and P. cyclopium synthesize ochratoxin A (OTA). P. citrinum and P. expansum are principal sources of citrinin, with the latter also producing patulin. In temperate countries, mycotoxin residues in cereal grains are largely the result of fungal disease of standing crops in the field. Consequently, host-pathogen interactions are important components in mycotoxin production. In warm humid tropical regions, fungal proliferation generally arises during post-harvest storage, particularly if the products have been inadequately dried, but the inoculum for these microorganisms may originate from field sources such as plant debris and soil. Current surveillance indicates widespread mycotoxin contamination of primary and processed plant products with global implications for human health. Concentrations of aflatoxins in maize and groundnuts regularly exceed safety threshold limits. OTA, certain trichothecenes and zearalenone occurr primarily in cereal grains and derived products. In addition, OTA may occur in dried vine fruits and green coffee beans. Of considerable concern is the widespread contamination of maize and associated products with fumonisins. The use of contaminated feedstocks in livestock nutrition may result in the transfer of mycotoxins to animal products, particularly milk and offal. Consequently, humans may be exposed to combinations of different foodborne mycotoxins. Although mycotoxins may be graded according to acute lethality tests, the major concerns in human health relate to epidemiological evidence. A broad spectrum of adverse outcomes has been associated with chronic exposure, including carcinogenesis, hepatitis, nephrotoxicity and endocrine disruption. Mycotoxins may compromise health by modulating other disorders. For example, foodborne aflatoxins may enhance the carcinogenic potential of hepatitis B virus. In addition, it has been proposed that kwashiorkor in African children may be a manifestation of aflatoxicosis. Nevertheless, in toxicological classification, aflatoxin B1 has been designated as a gro","PeriodicalId":236595,"journal":{"name":"A handbook of environmental toxicology: human disorders and ecotoxicology","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123318919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}