Just one example from Wikipedia-Politicization of science:
In July 2006 the Union of Concerned Scientists (UCS) released survey results that demonstrate pervasive political influence of science at the Food and Drug Administration (FDA). Of the 997 FDA scientists who responded to the survey, nearly one fifth (18 percent) said that they “have been asked, for non-scientific reasons, to inappropriately exclude or alter technical information or their conclusions in a FDA scientific document.” This is the third survey Union of Concerned Scientists has conducted to examine inappropriate interference with science at federal agencies.
The Department of Health and Human Services also conducted a survey addressing the same topic which generated similar findings.According to USA Today , a survey of Food and Drug Administration scientists by Public Employees for Environmental Responsibility and the Union of Concerned Scientists found that many scientists have been pressured to approve or reject new drugs despite their scientific findings concerns. In July 2006, the Union of Concerned Scientists released survey results that they said “demonstrate pervasive political influence of science” at the Food and Drug Administration.
The fact of the matter is, if money is involved, be it grants, funding, lobbyists, science will not be pure.