Actually, one of my husband's friends looked up some info on Swiffer Wet and this is what he came up with:

All,

Ok, this scared me a bit, and combined with some natural
curiosity and distrust of internet gossip, I decided to educate
myself. Here's what I learned. Please feel free to make
corrections (especially if you have a strong Chemistry
background)

Proctol & Gamble has a "Material Data Saftey Sheet", or
MSDS, available for most of their products. These things
tell you what's in the products, how it's expected to be
used/handled, etc., available here:

http://www.pg.com/content/pdf/01_abo...SwifferWet.pdf

This indicates that the active cleaning agent in swiffer wet
is 1-4% Propylene Glycol n-Propyl Ether.

The chemical profile for this substance is located here:
http://www.intox.org/databank/docume...nme/cie178.htm

CAS info here:
http://www.arb.ca.gov/db/solvents/so...HTML/pgnpe.htm

CDC Toxicology profile for Propylene Glycol
http://www.atsdr.cdc.gov/toxprofiles/tp96.html
http://www.atsdr.cdc.gov/tfacts96.html

Propylene Glycol is related to Ethylene Glycol (antifreeze), however
Propylene Glycol is considered safe and is used in food, and is
broken down very quickly. Propylene Glycol esthers are related
closely to Propylene Glycol(don't ask me how though). This chemical
evaporates quickly and does not leave a residue on the floors (kind
of like rubbing alcohol).

It IS toxic (as most solvents are) when swallowed, however, it requires
something on the order of 2.8 g/kg of body weight to be considered a
high dose and begin to show some evidence of kidney injury. A 25lb
dog is 11.33 kg. Such an animal would need to consume 31.724 grams
to have a have a mimimal high dose.

(31.724 grams * 100)/4 = 793 grams
At a 4% concentration, it would take 793 grams of swiffer fluid to
reach the high dose level. That's 1.748lbs of fluid. A Gallon is 8lbs,
so:

((1.748/8)*100) = 21.85% of a gallon = 3.496 cups.

The animal would need to have ingested nearly 3.5 cups of swiffer
wet fluid to have some evidence of kidney injury. And the effect is
not cumulative (except for topical irritation), so it would have to
have been ingested in a relatively short span of time. Using the
same math, a 9lb cat would have needed to drink 1.35 cups of
swiffer wet to reach the g/kg level required for toxicity, and a 75lb
dog would need to drink 11.25 cups.

Even if my methodology here was wrong (% by volume or % by
weight sort of issue, and it may well be, I'm no chem major),
it seems pretty clear to me the results would still indicate the
need for a fairly large amount of swiffer fluid to be swallowed
in a short amount of time to cause a problem.

I'm sorry for their loss, but unless proctor & gamble had a big
manufacturing error and bumped that 4% up close to 100%,
or they left the container open for the animals to drink from,
I just don't see how swiffers would have anything to do with it.

Not to say there wasn't something in the environment
causing a problem, just that the science doesn't support
this as the cause.