The FDA last formally reviewed the issue in 2011, when it concluded that a causal link between children's consumption of synthetic color additives and behavioral effects had not been established. At the time the agency also commissioned an exposure assessment of all seven color additives approved for use in food in the U.S.: FD&C Blue No. 1, Blue No. 2, Green No. 3, Red No. 3, Red No. 40, Yellow No. 5, and Yellow No. 6. The results of this study, later presented in 2014, revealed that between 2007 and 2010, some dyes were consumed on an almost daily basis by up to 98 percent of 2-to-5-year-olds, 95 percent of teenage boys aged 13-18, and 94 percent of the entire U.S. population aged 2 and up. "Exposure in children affects attention and behavior across the whole spectrum of the population, and it's a widely distributed exposure," Mark Miller, a public health medical officer with OEHHA and one of 13 authors of the report, told EHN. "Overall it means that the impact is subject to being fairly large." Mechanistic studies reviewed by Miller and the report's other authors reveal that food dyes may impact behavior through a variety of pathways including neurotransmitters, hormones, and oxidative stress. More research is needed on how dyes are absorbed, distributed, and metabolized in the body, they note. An FDA spokesperson said that the agency had received and was reviewing the report. "The FDA will continue to engage in the scientific and regulatory review of color additives to evaluate their potential impact on various populations, including children, and act when necessary to ensure that the products marketed to consumers are safe and properly labeled," the statement read. "Parents who wish to limit synthetic color additives in their children's diet may check the food ingredient list on labels, where they are required to be listed."