title: Ingestion of toxic Microcystis aeruginosa by dairy cattle and the implications for microcystin contamination of milk.
abstract: Microcystin (MCYST) toxins can be produced by the bloom-forming cyanobacterium Microcystis aeruginosa. They are chemically stable compounds and have both acute and chronic effects on the health of mammals, including cattle and humans. Cattle will drink water containing lethal cell concentrations of M. aeruginosa. When cattle consume sub-lethal doses of microcystins, the fate of those toxins is unknown. We provided drinking water containing 1 x 10(5) cells ml(-1) M. aeruginosa (strain MASH01-A19) to four lactating Holstein-Friesian dairy cattle for 21 days to determine if MCYST-LR produced by the cyanobacteria, could be detected in milk produced by the cattle. Cattle consumed up to 15 mg MCYST-LR at an ingestion rate of 1.21 microg kg (live weight) d(-1). Analysis by HPLC and ELISA indicated that no detectable amounts of microcystin from the cyanobacteria were present in the milk obtained from the treated animals. Based on the level of quantitation of the ELISA analyses, the maximum possible concentration in the milk was less than 2 ng l(-1). This is more than three orders of magnitude less that the concentration that could be considered problematic for milk of 0.86 microg l(-1) which we calculated using the World Health Organization derived tolerable daily intake for MCYST-LR and the per capita daily consumption of milk in Australia.
authors.affiliation: CSIRO Land and Water, 120 Meiers Rd, Indooroopilly, Queensland, 4068, Australia. philip.orr@bne.clw.csiro.au
authors.forename: P T
authors.initials: PT
authors.lastname: Orr
authors.forename: G J
authors.initials: GJ
authors.lastname: Jones
authors.forename: R A
authors.initials: RA
authors.lastname: Hunter
authors.forename: K
authors.initials: K
authors.lastname: Berger
authors.forename: D A
authors.initials: DA
authors.lastname: De Paoli
authors.forename: C L
authors.initials: CL
authors.lastname: Orr
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000032:analysis / Q000493:pharmacokinetics*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D004326:Drinking; D004435:Eating; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005516:Food Microbiology; D052998:Microcystins; D046931:Microcystis / Q000502:physiology*; D008892:Milk / Q000737:chemistry / Q000378:metabolism*; D010456:Peptides, Cyclic / Q000032:analysis; D014881:Water Supply
chemical_list: D001427:Bacterial Toxins; D052998:Microcystins; D010456:Peptides, Cyclic; C078588:microcystin