Cookies on Environmental Impact

Like most websites we use cookies. This is to ensure that we give you the best experience possible.


Continuing to use  means you agree to our use of cookies. If you would like to, you can learn more about the cookies we use.

Environmental Impact

From climate change to biodiversity loss - documenting human impacts on the environment

>>> Sign up to receive our Environmental Sciences newsletter, book alerts and offers <<<

CABI Book Chapter

A handbook of environmental toxicology: human disorders and ecotoxicology.

Book cover for A handbook of environmental toxicology: human disorders and ecotoxicology.


Chapter 2 (Page no: 19)


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 group 1 carcinogen, specifically implicated in liver, lung and gallbladder malignancy. Epidemiological evidence also links human oesophageal cancer in South Africa with dietary exposure to fumonisins. This group has been cited as a possible contributory risk factor in primary hepatocellular cancer in China. OTA has been linked with the incidence of Balkan (and possible Tunisian) endemic nephropathy, but the co-occurrence of OTA with citrinin suggests an interaction between the 2 mycotoxins. Current studies focus on molecular and biochemical dimensions, particularly in the context of mycotoxin-induced carcinogenesis. In the case of aflatoxin B1, this work includes nucleotide excision repair, DNA adduct reduction, cellular gene expression modulation, signalling pathways activation, mutational spectra, microRNA expression, interferon anti-cancer pathway and factors in cancer cell migration. It is envisaged that molecular and biochemical investigations should resolve cause-and-effect issues raised by epidemiological evidence and assist in evaluating alternative mechanisms in the aetiology of hepatocellular carcinoma. There may be scope for the characterization of improved biomarkers for the assessment of mycotoxin-induced human malignancy. Despite enhanced awareness of health risks and the adoption of legal or advisory guidelines, human exposure to foodborne mycotoxins continues unabated and on a global scale. The evidence for residues of aflatoxins and OTA is particularly striking as demonstrated by analysis of body fluids, mother's milk and tissue specimens. Further studies are being undertaken to establish or confirm the link between mutational fingerprints and mycotoxin exposure. Of considerable concern in environmental toxicology is the inefficacy of fungicides to control fungal diseases of plants and, therefore, mycotoxin contamination of harvested grain. The development of fungicide resistance in these fungal phytopathogens is an added risk. It is concluded that factors such as ecology, environmental temperature and humidity or substrate water activity predispose to production of mycotoxins by plant pathogenic and saprophytic fungi, resulting in worldwide contamination of staple foods. These compounds constitute a continuing hazard to human health following acute and/or chronic exposure. Measures to mitigate risk, such as the use of fungicides and preservatives, are of limited efficacy. The use of sub-lethal doses or the development of fungicide resistance may exacerbate potential hazards.

Other chapters from this book

Chapter: 1 (Page no: 3) Phytotoxins. Author(s): D'Mello, J. P. F.
Chapter: 3 (Page no: 33) Cyanobacterial toxins. Author(s): Metcalf, J. S. Souza, N. R.
Chapter: 4 (Page no: 49) Amino acids and peptides as mediators of abiotic stress tolerance in higher plants. Author(s): D'Mello, J. P. F.
Chapter: 5 (Page no: 75) Ozone I. Human disorders: an overview. Author(s): Silveyra, P. Fuentes, N. Rivera, L.
Chapter: 6 (Page no: 93) Ozone II. Biophysical observations. Author(s): Thompson, K. C.
Chapter: 7 (Page no: 105) Nitrogen dioxide: ambient exposure in human disorders. Author(s): Huang, Y. C. T. Tucker, J. L.
Chapter: 8 (Page no: 114) Sulfur dioxide and human disorders. Author(s): Ahmad, S. Ahmad, A. Ahmad, A.
Chapter: 9 (Page no: 127) Plant response to acid rain stress. Author(s): Liang, C.
Chapter: 10 (Page no: 141) Polycyclic aromatic hydrocarbons: ecotoxicity in the aquatic environment and implications for human health. Author(s): Pampanin, D. M. Schlenk, D.
Chapter: 11 (Page no: 156) The developmental neurotoxicity of polychlorinated biphenyls: a continuing environmental health concern. Author(s): Sethi, S. Lein, P. J.
Chapter: 12 (Page no: 173) Dioxins I. Dynamics and legal directives in Europe. Author(s): Dopico, M. Gómez, A.
Chapter: 13 (Page no: 187) Dioxins II. Human exposure and health risks. Author(s): Tuomisto, J. Viluksela, M.
Chapter: 14 (Page no: 206) Dioxins III. Relationship to pre-diabetes, diabetes and diabetic nephropathy. Author(s): Everett, C. J.
Chapter: 15 (Page no: 214) Environmental endocrine-disrupting chemicals and human health. Author(s): Darbre, P. D.
Chapter: 16 (Page no: 233) Organochlorine insecticides: neurotoxicity. Author(s): Caudle, W. M.
Chapter: 17 (Page no: 246) Organophosphates I. Human health effects and implications for the environment: an overview. Author(s): Wille, T. Thiermann, H. Worek, F.
Chapter: 18 (Page no: 261) Organophosphates II. Neurobehavioural problems following low-level exposure: methodological considerations for future research. Author(s): Ross, S. J. M. Harrison, V.
Chapter: 19 (Page no: 282) Glyphosate as a glycine analogue. Author(s): Seneff, S.
Chapter: 20 (Page no: 299) Crude oil pollution I. Deepwater Horizon contamination: human health effects and health risk assessments, a case study. Author(s): Wilson, M. J.
Chapter: 21 (Page no: 311) Crude oil pollution II. Effects of the Deepwater Horizon contamination on sediment toxicity in the Gulf of Mexico. Author(s): Montagna, P. A. Arismendez, S. S.
Chapter: 22 (Page no: 320) Crude oil pollution III. Exxon Valdez contamination: ecological recovery, a case study. Author(s): Haycox, S.
Chapter: 23 (Page no: 334) Review of studies of composition, toxicology and human health impacts of wastewater from unconventional oil and gas development from shale. Author(s): Crosby, L. M. Orem, W. H.
Chapter: 24 (Page no: 353) Minamata disease and methylmercury exposure. Author(s): Hachiya, N.
Chapter: 25 (Page no: 371) Lead poisoning. Author(s): Katner, A. L. Mielke, H. W.
Chapter: 26 (Page no: 384) Cadmium I. Exposure and human health effects: an overview. Author(s): Åkesson, A. Kippler, M.
Chapter: 27 (Page no: 394) Cadmium II. Cardiovascular effects of human exposure to cadmium: left ventricular structure and function. Author(s): Yang, W. Y. Staessen, J. A.
Chapter: 28 (Page no: 405) Particulates from combustion sources: formation, characteristics and toxic hazards. Author(s): Purser, D. A.
Chapter: 29 (Page no: 424) Assessment of the ecotoxicity of airborne particulate matter. Author(s): Kováts, N.
Chapter: 30 (Page no: 436) Toxicity of microplastics in the marine environment. Author(s): Santana, M. F. M. Turra, A.
Chapter: 31 (Page no: 457) UV exposure and skin-protective effects of plant polyphenols. Author(s): Agulló-Chazarra, L. Pérez-Sánchez, A. Herranz-López, M. Micol, V. Barrajón-Catalán, E.
Chapter: 32 (Page no: 475) Radon I. Lung cancer risks. Author(s): Melloni, B.
Chapter: 33 (Page no: 484) Radon II. Leukaemia or CNS cancer risks among children. Author(s): Kollerud, R. del R.
Chapter: 34 (Page no: 497) Fukushima nuclear accident: potential health effects inferred from butterfly and human cases. Author(s): Otaki, J. M.
Chapter: 35 (Page no: 517) Microbial remediation of contaminated soils. Author(s): Shahsavari, E. Mansur, A. A. Aburto-Medina, A. Haleyur, N. Jones, N. Ball, A. S.
Chapter: 36 (Page no: 531) Metallic iron for environmental remediation: prospects and limitations. Author(s): Noubactep, C.
Chapter: 37 (Page no: 545) Remediation of contaminated soil by biochar. Author(s): Sima, X. F. Jiang, H.
Chapter: 38 (Page no: 561) Environmental regulations in China. Author(s): He, G. Z.
Chapter: 39 (Page no: 577) 21st Century toxicology: methods for environmental toxicology and monitoring. Author(s): Lundqvist, J.
Chapter: 40 (Page no: 587) Unequivocal evidence associating environmental contaminants and pollutants with human morbidity and ecological degradation. Author(s): D'Mello, J. P. F.