Well, just recently Lennard Zinn (of VeloNews) fielded just this question. While he wasn't able to provide much of an answer (other than "huge", which I'd agree with) he DID mention a ghastly practice of many of the team mechanics-- cleaning bike with diesel fuel! And then just dumping the rinsate on the parking lots which then drain into nearby waterways.
I’ll let you calculate that, as I don’t know how to do it. I would imagine that on average each of the 22 teams has five station wagons with roof racks full of bikes, one bus and one truck, all of which drive an average of 200km per day. Then of course there’s laundry, food, lodging, etc. And that’s only the tip of the iceberg compared to the entire race itself. Think of all of the transport of race barriers, grandstands, concessions, start village, etc., not to mention transport and lodging of the fans, publicity caravan, media, organizers, etc. Big footprint.
But if you’re interested in environmental impacts of the race, nothing grates me more than team mechanics who continue to use diesel fuel to clean bikes, spraying it and dumping it in parking lots of, for example, seaside hotels along the Lido di Jesolo in the days before the Giro’s start. Many do use biodegradable cleaners, but plenty don’t, and the first rainstorm it goes right in the Adriatic.
(Excepted from VeloNews Technical Q&A with Lennard Zinn)
What the hell?
I think that the ProTour teams need an injection of badassery. Enough of this ridiculous pampering and ourtrageous pollution.
They need to ride a dirty bike and have it last. A dirty bike is a working bike.
Contrary to what the nicenastys over at BKW may claim about looking PRO, some buildup of road grime or mud actually demonstrates PRO-ness. The dirt says "I ride." A dirty bike and a well-maintained bike aren't mutually exclusive.
For most of the time all my bikes have encrustations of dirt. When they do get cleaned it's typically a "dry" cleaning-- a toothbrush gets rid of excessive buildup. A good chain-lube precludes the need for constant degreasings and cleanings.