i spend most of my lunch break under a yew for three days a week when im coppicing and have been doing this for years, unless you eat it i would say your ok 
i would me more worried about sudden limb drop which affects all braod leaf trees, i spent alot of time over the spring and early summer removing limbs that had snapped out. which this year seemed to be oak as they came out in leaf first this year before the ash trees.....

i would me more worried about sudden limb drop which affects all braod leaf trees, i spent alot of time over the spring and early summer removing limbs that had snapped out. which this year seemed to be oak as they came out in leaf first this year before the ash trees.....