Food safety and residues in Australian agricultural produce.

A brief history of food safety in Australia in the context of the development of scientific knowledge is presented. Australia's food and food commodity residue and contamination surveillance and monitoring programs are outlined. Although chemical residues are perceived as a major health risk by the general community, the risk of food causing illness or death because of chemical residues is low. The major threat to human health from food is microbiological contamination, in terms of deaths, sickness and economic loss. The emerging influences in food safety are scientific and technical developments, deregulation, social and demographic factors, and the media. The risk of disruption of domestic and export markets by food safety issues is considerable. The emergence of international standards for food production and processing will enable commercial contractual arrangements to minimise the frequency of disruptive food safety incidents.

Programs for surveillance and monitoring of antibacterial residues in Australia, 1989 to 1993.

The development of a State-based confirmatory testing capability for antibiotic residues in meat in Australia has allowed the rapid feedback to producers failing to comply with antibiotic maximum residue limits. The identification of problem areas in various categories of livestock, and subsequent focused surveillance programs, has reduced the prevalence of antibacterial residues in both domestic and export meat products. Failure to observe withholding periods of antibacterial drugs after treatment is the most significant cause of non-compliance. In the period July 1991 to June 1993 the compliance rate for antibacterial residues for all species was 99.9%.

Monitoring and surveillance in abattoirs of residues of antibacterial substances--a description of programs in Australia and the USA.

Australia and the USA are major international meat exporting countries. Both countries conduct programs to monitor and survey for antibacterial residues. Australian programs use a urine screening test, whereas the US programs use tissue fluids as the test medium. The development of surveillance programs to provide rapid feedback to producers is a feature of the Australian programs. The programs in each country compare favourably with regard to numbers of animals tested, results and action taken to prevent residues. The results of the Australian programs justify the promotion of a 'clean food' image for Australian meat products with respect to antibacterial drugs.

Differences in blood supply to the cerebral cortex between sheep and calves during slaughter.

Using methylene blue boli, injected via an intracardiac catheter, the blood supply to the brain in two one- to 10-day-old calves and three adult sheep was studied during and after severance of the common carotid arteries and jugular veins. Passage of dye through cerebral vessels could not be observed in the exposed cerebrum of sheep after bilateral severance of major blood vessels. When vessels were severed on one side only, the passage of dye was noted for at least 53 seconds. In calves, after bilateral severance, sequential boli of dye could be detected passing through the cerebral vessels for more than 100 seconds. These results provide an explanation and support for the belief that there are major differences in the onset of insensibility between sheep and calves subsequent to severance of the common carotid arteries and jugular veins. The differences in blood supply to the brain which were demonstrated could be accounted for by differences in the blood supply to the brain by the vertebral artery in sheep and cattle. The effects of slaughter on the blood supply to the eye are discussed as a possible explanation of the disparity between results of studies in this general field which have used retinal responses in their investigations and those which have not.