21.   He argued that there is no scientific proof that nitrogen oxide from West Virginia can reach Massachusetts, as Massachusetts argued.

22.   Her concern is that transplants are rapidly becoming the treatment of choice without the scientific proof that they are the best therapy.

23.   His scientific proof?

24.   Humbug, say geologists and minerologists, who claim there is no scientific proof that crystals and rocks emit any kind of healing energy.

25.   Killian said that if the initiative passes, drugs such as heroin and LSD could be used only if there is scientific proof that those drugs have medical benefit.

26.   Now is the time to act to reduce levels of homocysteine, even though definitive scientific proof is lacking.

27.   One reason has been the lack of scientific proof that human activities are responsible for the warming.

28.   Previously, the government said there was no scientific proof of such a link.

29.   Still, scientific proof is elusive.