"It was the first time in a GPDA meeting I have ever been to in my life where absolutely all - not one - showed any doubt.
"It is not worth taking any more risks. Boycotting is not the word at all: it is about being safe."
The GPDA does not represent Lotus driver Kimi Raikkonen, Force India's Adrian Sutil and Williams's Valtteri Bottas. Bottas told BBC Sport on Friday: "I'm racing."
Last weekend at Silverstone six drivers suffered on-track failures.
The drivers have been concerned about tyre safety for some weeks, following a series of failures at the earlier races in Malaysia, Bahrain and Spain, and following Silverstone governing body the FIA has stepped in to ensure changes are made.
Andrew Bensonat the Nurburgring
The statement put out by the Grand Prix Drivers' Association on Thursday said the drivers - or at least those in the GPDA - would "immediately withdraw" from the event if there were "similar problems" to the tyre failures seen at Silverstone.
The question is what exactly does that mean? It certainly leaves lots of wriggle room. From talking to senior drivers, it certainly does not mean that if there is one puncture they will all simply get out of their cars.
The likelihood is they would finish the session they were in, try to find out what happened and then discuss it because obviously racing tyres can fail, however robust they are. That can never be ruled out. It's also worth saying that the drivers do not expect there to be any problems at this track - but they are seriously concerned about tracks such as Spa in Belgium and Suzuka in Japan, and are pleased Pirelli is planning to change the tyres fundamentally after this race.
De La Rosa said that should problems arise in the race, it would be FIA race director Charlie Whiting's decision as to whether it should be stopped.
Pirelli motorsport director Paul Hembery said he found the GPDA statement "a little strange" but admitted on Friday that the company had made some errors in how it allowed the teams to run their tyres.
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