The findings, by Cornell University researchers, were presented at the American Association for the Advancement of Science annual meeting on Sunday.
The researchers conducted four annual national surveys from 2003 to 2005, and three annual surveys of New Yorkers during the same period, with a total of almost 5,000 respondents.
The surveys, which were all "very consistent" with each other, revealed that 38 percent of respondents in 2005 perceived GE foods as "high risk," compared to 27 percent in 2003.
This "slight but significant shift" toward "less support and more risk perception" may be connected to the decline in media coverage of biotechnology during the period, said the researchers, who found that the more attention people paid to the news, the more likely they were to support GE food.
"Overall, research shows that GE foods are safe and effective, though some people still harbor reservations about it," said lead researcher James Shanahan. "I suspect that the more people are exposed to the news, the more aware they are of biotechnology and, therefore, more supportive of it."
"As it moved out of the news, biotechnology became more tied to other attitudes about science and what's natural," added researcher John Besely.
"Biotechnology carries a certain 'yuk-factor' for some people. People could have relied on their basic instincts rather than having thought through the issue," he told FoodNavigator-USA.com.
However, he added that the research did not examine consumer behavior, and he was unable to comment on the impact of the changes in consumer perception on sales of foods containing genetically modified ingredients.
The study also revealed that while some people feel biotechnology is beneficial, others believe it has negative effects on health and the environment.
Women and non-Caucasians were also found to harbor less support for GE food than men and Caucasians.
According to the researchers, recent estimates suggest that more than two thirds of the food in the US contains some amount of a genetically engineered crop, with corn and soybeans being the crops to be most frequently modified, followed by canola and cotton.