The crystal was cut and studied in a vacuum to avoid contamination of the surface. (sciencedaily.com)
To avoid contamination from food, don't use a double feeder that has food on one side and water on the other. (catbehaviorassociates.com)
But this complex reality must not lead us to believe that a retreat to more traditional forms will simply provide us with the possibility of avoiding all contamination in communication. (religion-online.org)