Hmm, good question. I haven't taken a critical writing course in so long, it's hard to say. I'd guess it's somewhat matter-of-fact, somewhat persuasive (he's trying to sell a point), but mostly just like a documentary of findings that he himself finds shocking and ultimately resigned to.

There's a lot of interesting history in the book, like the German chemical warfare expert who is the father of man-made fertilizer, and the origins of the "organic food" movement and its pioneers.

I'm only 1/3 way through, so I can't discuss much more right now.