Hugh Pennington: This is shocking – diners should be worried

It is customary to describe a simple, logical, and easy to understand work process as "not rocket science". This is true for food safety.

But paradoxically, the system adopted worldwide to deliver it – hazard analysis and critical control points (HACCP) – came from the space programme. It was developed by Nasa because the trouble caused by poor food safety in zero gravity was too awful to contemplate.

HACCP is simple. It concentrates on "critical control points": the factors that must be got right to deliver safe food. It has prerequisites: such as having a clean kitchen and hand basins with soap. Essentially, these are the legal requirements. They are neither onerous nor bureaucratic.

And that is what makes these results so disturbing. Any restaurant scoring 2* (more effort required to meet all legal requirements) is unsafe. Lower scores indicate danger. I would expect those with a score of zero to have been closed. To find chain restaurants with scores of two stars or less is shocking. Any with zero is a scandal. These ratings should be displayed prominently in the outlets: a wise restaurateur would use them as a marketing tool; the others should get their act together and improve their score.

The public, meanwhile, should be concerned. If a restaurant is cutting corners with hygiene then it is contaminating food which, ultimately, has the potential to kill.

But these ratings are entirely preventable by having good food practices implemented. As the figures show, there are all sorts of good sound business reasons, as well as those of public health, to go for the top ratings. Low hygiene figures let the brand down.

That the burger bars did better than some is no surprise. The impact of E.coli O157 outbreaks in the US in the 1980s and 1990s caused them to protect their shareholders by paying attention to food safety. Edwina Currie's comments in December 1988 that British eggs had salmonella was also constructive. Margaret Thatcher introduced the Food Bill in 1989, which became law the following year. With amendments it still lays down the rules which environmental health officers use.

The publication of "scores on the doors" findings reflects the current tendency for openness, the driver of which is the Food Standards Agency (FSA). Similarly, the force that impelled its creation in 2000 was BSE. Few would disagree that the FSA is effective, but food poisoning has not gone away.

Poor hygiene in restaurants is bad business as well as bad public health, and customers should simply avoid restaurants with star ratings of zero, one or two like the plague.

Hugh Pennington is Emeritus Professor of Bacteriology, University of Aberdeen