A Hong Kong regulation came into force Friday barring people from crossing into mainland China with large quantities of baby formula following chronic shortages which have fueled anti-Beijing sentiment.

Formula is popular with mainland Chinese because of concerns about the safety of food processed in China after a series of scandals, notably in 2008 when six babies died from drinking milk tainted with the chemical melamine.

Horsemeat has been found in ground beef supplied to Taco Bell's three restaurants in Britain after tests sparked by Europe's sprawling food scandal, the U.S. fast food giant said Friday.

Taco Bell said it was "disappointed" by the discovery and had immediately withdrawn ground beef from the restaurants, two of which are in shopping centres in Essex, east of London, and one of which is in Manchester, northwest England.

Health-related applications for smartphones and tablets are a booming business, but in Africa and Asia "mobile health" could actually be a lifesaver for millions, industry leaders and aid organisations say.

Mobile phones could save up to a million lives over the next five years in sub-Saharan Africa, according to a report by mobile industry association GSMA and global consultants PwC released at the February 25-28 Mobile World Congress in Barcelona.

Giving inmates drug substitution treatment, needles and condoms are key ways to help curb addiction and HIV infection in European jails, experts say, calling on authorities to change their approach to prison health care.

"We support opioid substitution treatment and harm reduction measures, including needle exchange programs. These measures are crucial, otherwise we cannot tackle HIV and other infections in prisons," Stefan Enggist of the World Health Organisation (WHO) said during an international conference on addiction in prisons organised by the Council of Europe this week in Bucharest.

Increased awareness and use of electronic cigarettes in the U.S. outlined in a study released Thursday highlights the need for government regulation and evaluation, the head of the Centers for Disease Control and Prevention's office on smoking and health said.

Nearly six in 10 adults in the U.S. are aware of the battery-powered devices that heat a liquid nicotine solution and create vapor that users inhale, according to the first study to assess the change in awareness and use of electronic cigarettes on a national level. The CDC report published in the journal Nicotine & Tobacco Research also said about one in five current smokers reported having used an electronic cigarette.

The head of the World Health Organization's polio drive said Friday it was crucial to push on with the fight to eradicate the disease despite a rising death toll among vaccination workers.

A Pakistani policeman was shot dead earlier this week while protecting a polio team, police said, bringing the number of deaths in such attacks in the troubled country to 20 since December.

Morning sickness is an all-too-common side effect of pregnancy, and a new study out Wednesday said a medication used to treat the most serious cases is safe for fetuses.

The trials of pregnancy-induced nausea -- and its more devastating cousin, hyperemesis gravidarum -- have made headlines lately, with celebrity moms and moms-to-be from Kate Middleton to Kate Winslet publicly suffering through it.

Japan's 2011 Fukushima nuclear disaster has raised the risk of thyroid cancer in the plant's immediate area, but no jump in cases is expected elsewhere, the WHO said Thursday.

The World Health Organisation said in a report that within a 20-kilometer (12-mile) radius of the plant, rates of thyroid cancer among women who were exposed to the radiation as infants were expected to be up to 1.25 percent, up from the normal 0.75 percent.

After withdrawing meatballs from stores across Europe, home furnishings company Ikea said Wednesday its own tests confirmed "a few indications of horse meat" and that it would also remove wiener sausages made by the same supplier.

Meanwhile, Poland acknowledged for the first time that it is a source of horse meat that has fraudulently ended up in processed meat products sold as beef — an admission that came as the country said it found traces of horse DNA in samples from three meat processors.

Jack Andraka catapulted from being a typical U.S. teenager unaware of the pancreas to one with a cheap way to detect cancer in the organ before it turns deadly.

"Through the Internet, anything is possible," Andraka said while telling the story of his screening breakthrough at a prestigious TED Conference in Southern California on Wednesday.