Hong Kong's food-safety standards are at their highest level in three years, according to the Food & Environmental Hygiene Department.

The department tested 54,000 food samples for microbiological and chemical dangers in 2002. The overall failure rate was 0.3%. This has fallen from 0.5% in 2001, and 0.07% in 2000, the year the department first began such stringent testing.

The department's Assistant Director Dr Gloria Tam said microbiological tests targeted pathogenic bacteria and viruses, while chemical tests were for the detection of natural toxins, food additives and contaminants.

About 19,000 food samples were taken for microbiological tests, with pathogens found in 19 samples.

This amounts to a failure rate of 0.1%, compared with 0.3% in both 2000 and 2001.

The pathogen-food combination that came under particular attention last year was the bacterium Enterobacter sakazakii, found in an infant formula specially prepared for babies suffering from acute diarrhoeal diseases. 

Cases in foreign countries showed that vulnerable infants - such as premature babies in hospital, low birth-weight and babies with underlying medical conditions - can fall ill after consuming infant formula contaminated with the bacterium.

By introducing a risk-based and proactive sampling and lab-analysis programme for Enterobacter sakazakii, the department detected, traced and, with the co-operation of the trade and the community, contained the contamination within a short time. No infections were reported.

Nevertheless, Dr Tam she called on manufacturers to exercise due diligence as well to safeguard public health.

Norwalk-like virus was also found in ready-to-eat oysters last year.

Being infected by this virus can result in what is known as 'winter vomiting disease', Dr Tam explained.

Outbreaks usually occur in winter and the clinical presentation can be dramatic as there are usually many victims and they typically have projectile vomiting and other gastrointestinal symptoms.

She strongly advised susceptible groups like the young, the elderly and pregnant women to refrain from eating this kind of high-risk food.

About 35,000 food samples were tested for chemical analysis last year, and 140 were found unsatisfactory, representing a failure rate of 0.4%.

The figures for 2000 and 2001 were 0.9% and 0.6% respectively.

Dr Tam highlighted that a non-permitted sweetener, stevioside, was found either on sale in the market or contained in food items being sold in March last year. 

This resulted in the recall of certain food brands, ranging from pure sweeteners to seasonings, instant noodles to snacks.

"We reminded the food sector to act responsibly to check what food additives are permitted for use in foods on sale here before releasing their commodities into the market," she added.

On the banned beta-agonists, only four food samples were found to contain clenbuterol and salbutamol last year, compared with 53 and 25 in 2000 and 2001, respectively.

Dr Tam urged farmers who bred animals for food to continue to adopt good husbandry practice, abstain from abusing prohibited drugs while observing drug withdrawal periods for those on the restricted list.

For biotoxins, there were three failed samples for ciguatoxin and one for paralytic shellfish poison last year, much lower than in the previous two years.

In 2000, there were 47 ciguatoxin and three paralytic shellfish poisons found; in 2001, there were 10 ciguatoxin and five paralytic shellfish poisons found. 

Since their presence and levels in coral reef fish and shellfish can be very unpredictable, Dr Tam called on the public to be on the alert as the toxins are natural ones.

She said: "There are seasonal patterns in Hong Kong. During the two peak periods, in spring and the transition from summer to autumn, people should be extra cautious when eating coral reef fish and shellfish."

One practical tip is to avoid large coral reef fish such as flowery grouper, tiger grouper, leopard coral grouper and moray eel, especially those weighing more than three catties, as they are more likely to be involved in ciguatoxin food poisoning.