“For many years it was believed that the harmful effects of all toxic chemicals increased with an increasing dose or exposure, and that there was a low threshold dose below which there was no harmful effect. It was also assumed that both adults and children responded similarly to toxic exposures. Scientific evidence now shows that some chemicals, especially endocrine disrupting compounds, can exert negative effects at extremely low levels of exposure, sometimes with more serious or different effects than at higher doses. The timing, duration and pattern of exposure are just as important as the dose. While it’s good to limit exposure to toxic chemicals and radiation at every stage of life, it is even more important during critical periods, including gestation, childhood and pregnancy.”