An individual may provide or share their personal information with scores of individuals (E.g. emailing and networking) and dozens of organisations and agencies, statutory, charitable and commercial.
Over time an individual may vary in their willingness to share their personal information, or in the degree of caution they exercise. E.g. children may share freely until they actually experience negative consequences. Conversely, older people may be initially reluctant to share due to anxieties about online crime.
It may be difficult for many individuals to keep track over time of the extent of their sharing of personal information, and how others may aggregate their information and use it for purposes never originally intended. In relation to this issue, the main response has to be through regulation, supplemented by developing (And keeping up to date) a much greater understanding by individuals of how personal information is used.