title: Cyanotoxins in desert environments may present a risk to human health.
abstract: There have been few studies concerning cyanotoxins in desert environments, compared with the multitude of studies of cyanotoxins in aquatic environments. However, cyanobacteria are important primary producers in desert environments, where after seasonal rains they can grow rapidly both stabilising and fertilising arid habitats. Samples of cyanobacteria from wadis - dry, ephemeral river beds - and sabkha - supertidal salt flats - in Qatar were analysed for the presence of microcystins, nodularin, anatoxin-a, cylindrospermopsin and anatoxin-a(S). Microcystins were detected by HPLC-PDA and ELISA at concentrations between 1.5 and 53.7ngg(-1) dry wt of crust. PCR products for the mycD gene for microcystin biosynthesis were detected after amplification of DNA from desert crust samples at two out of three sample sites. The presence of anatoxin-a(S) was also indicated by acetylcholine esterase inhibition assay. As a function of area of desert crust, microcystin concentrations were between 3 and 56μgm(-2). Based on the concentration of microcystins detected in crust, with reference to the published inhalation NOAEL and LOAEL values via nasal spray inhalation of purified microcystin-LR in aqueous solution, and the amount of dust potentially inhaled by a person from these dried crusts, the dose of microcystins could exceed a calculated TDI value of 1-2ngkg(-1)day(-1) for an average adult. The presence of microcystins, and potentially of anatoxin-a(S), in desert crusts has important implications for human health. Further studies are required to monitor desert dust storms for the presence of cyanotoxins. An understanding of the risks of inhaling particles containing cyanotoxins is also warranted.
authors.affiliation: Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 4HN, UK. james@ethnomedicine.org
authors.forename: J S
authors.initials: JS
authors.lastname: Metcalf
authors.forename: R
authors.initials: R
authors.lastname: Richer
authors.forename: P A
authors.initials: PA
authors.lastname: Cox
authors.forename: G A
authors.initials: GA
authors.lastname: Codd
mesh_terms: D000470:Alkaloids; D001427:Bacterial Toxins / Q000032:analysis* / Q000633:toxicity; D000087522:Cyanobacteria Toxins; D004247:DNA / Q000235:genetics; D003889:Desert Climate; D004391:Dust / Q000032:analysis; D004781:Environmental Exposure / Q000009:adverse effects / Q000032:analysis; D015386:Hazardous Substances / Q000032:analysis* / Q000633:toxicity; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects / Q000032:analysis; D008387:Marine Toxins / Q000032:analysis* / Q000633:toxicity; D052998:Microcystins / Q000032:analysis* / Q000235:genetics / Q000633:toxicity; D016133:Polymerase Chain Reaction; D011780:Qatar; D018570:Risk Assessment; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis* / Q000633:toxicity; D014498:Uracil / Q000031:analogs & derivatives / Q000096:biosynthesis
chemical_list: D000470:Alkaloids; D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D004391:Dust; D015386:Hazardous Substances; D008387:Marine Toxins; D052998:Microcystins; D012989:Soil Pollutants; C089595:cylindrospermopsin; D014498:Uracil; C078588:microcystin; D004247:DNA