Juvenile SF series, 1970s, white covers with thin Futura text, female author?

I remember a series of children's / juvenile SF books at my local library in the 1970s. Slim books, white spines, illustrated covers and some interior illustrations maybe, may not all be the same author but in my mind the name "Eve" seems to be attached - I had thought maybe Eve Bunting and/or Monica Hughes based on other searches, although none of their books that I can find match what I remember:

• Story about people on a ship going to colonize a new world, only realizing along the way that they have shrunk to live someplace smaller? - there was a mention of "R factor" meaning Reduction factor as part of the star drive system.


• Another story about an accident in a lab spilling a substance down a drain, which manages to somehow pollute the entire world; anyone who comes into contact with it dissolves rather horribly into red jelly.

Thanks in advance for any help!