A European Internet study has an instant message for parents who want to control their children's online habits: web filters are not 100 percent foolproof against harmful sites.
A solid 84 percent of programmes restrict access to websites such as porn pages, according to a study released by the European Commission on Thursday.
But they still leave a 20 percent chance for sites with content unsuitable for children -- webpages promoting anorexia, suicide and self-mutilation -- to escape the filters.
The study also found that few Internet filters can block "Web 2.0" content including blogs, forums and social networking sites such as Facebook or Twitter, or filter out instant messaging services.
For parents whose web-savvy kids use smart phones or video game consoles to access the Internet, not all products on the market provide parental controls for such platforms.
Computers are no longer the only way to go online: 31 percent of children access the Internet with their phones and a quarter through platforms such as the Nintendo Wii or Sony's PlayStation, the study found.
A survey released in parallel to the study found that only a quarter of parents in the European Union use parental control software to monitor, track or filter online content.
The use of such software varies widely among parents in the 27-nation EU, from 54 percent in Britain to nine percent in Romania.
The EUKidsOnline survey was conducted in 25 countries with more than 25,000 children and one of their parents between April and August 2010.
The study on filtering software analysed 26 parental control tools for PCs, three for game consoles and two for mobile phones.
The goal is to give parents an "objective view" of which softwares is the most effective, said Jonathan Todd, spokesman for European digital agenda commissioner Neelie Kroes.
"Protecting children from unsuitable content on the internet is of course an important issue," said Jonathan Todd, spokesman for European digital agenda commissioner Neelie Kroes.
"We want people in general, parents and children, to feel confident when they use the Internet," he said.
The study was funded by the EU's Safer Internet Programme, an initiative aimed at informing parents and children about the Web's potential risks.
The 2009-2013 programme has a budget of 55 million euros and will fund a review of parental control software every six months until the end of 2012.
The programme's website provides two lists ranking the effectiveness of the 26 software programmes for children 10 years old and younger and those over 11 years old.
Apple's Mac OS X topped both lists while rival Microsoft's Windows Vista was second for children under 10 and in ninth place for those over years old.
The list and full report are available at www.yprt.eu/sip/
Explore further: NFL, YouTube partner to post official clips to video site