Students can compare toys past and present. The article points to the use of phthalates today and compares them with earlier, more brittle, plastics.
You could use collections from a toy museum (see http:toy.co.ukmuseums for ideas) and see that early toys were made of tin (plenty of sharp edges there), or lead. The paint was infamous for containing white lead.
Students might consider the ways in which chemicals that were once thought to be safe later turned out to be dangerous. A good example is asbestos, widely used in the rapid building of housing after the Second World War.
KS2-3, and some courses at KS4 could get some much needed perspective by looking at the benefits of the chemical industry as well as the downsides.
The most obvious is the development of antibiotics and other "wonder drugs" in the early 20th-century. A good starting point is at www.schoolshistory.org.ukmedicine.htm