Its in use since 1950s. And its safer by a mile than others when taken in reccomended doses. If there was significant corelation there would have been much more proof.
Its pain relief effect could be minimal considering other heavier drugs in the market. But its always been enough for me, including crippling body pain in Chicken pox with just 1800mg during the whole day.
Honestly its a miraculous drug. All others are double edged swords.