As in many citation styles, APA allows that a government entity or an organization can be the author of a work.
This article has no listed author. The page "How does lead get into my tap water?" is in a section called Lead. The URL is http://www.cdc.gov/nceh/lead/tips/water.htm. It was last updated 2016 and likely to updated again. If something in APA is likely to be updated, use a retrieval date.
For lead poisoning, "risk will vary, however, depending on the individual" (Centers for Disease Control and Prevention, 2016, para. 5).
The Centers for Disease Control and Prevention (2016) says call your water authority immediately If the water has levels of lead above 15 ppb (para. 5).
This article has no author. It also has a video. You are using a section from the pagePregnancy. There is a 2016 copyright notice at the bottom of the page. This page is not an article or a page from a book so it is subject to be changed so use the retreival date. The URL is http://www.marchofdimes.org/pregnancy/before-pregnancy.aspx