Biomonitoring California was created to identify the presence of toxic chemicals in Californians. This knowledge can help shape public health and environmental policies. Through biomonitoring we can better understand Californians’ exposures to environmental chemicals. For example, this information can show whether exposures to certain chemicals are increasing or decreasing, and whether some groups of people are more exposed than others to specific substances. Scientists can use this information to explore whether exposures to certain chemicals may contribute to the development of specific diseases. It can be used to help evaluate environmental protection programs and, as appropriate, make changes to improve the health of Californians.