Felt tip markers
Acute toxicity of marking pen emissions. 
by Rosalind Anderson and Julius Anderson
Journal of Toxicology and Environmental Health Part A. 
Vol 66, pages 829-845, 2003.

We have received complaints fron several individuals 
who cannot tolerate the fumes of felt tip markers. 
They complain of blurrred vision, nasal congestion, 
headache, dizziness, difficulty concentrating, drowsiness, 
and difficulty breathing. These markers are the pens you use 
to write on white boards, the boards which have replaced 
chaulk black boards in most schools. When we visit school 
rooms, we frequently find twenty or more felt tip markers 
open in use or sitting on a table, and the smell is sometimes 
overwhelming.

We exposed groups of laboratory mice to the fumes released 
by several brands of felt tip markers. We collected scientific 
data demonstrating irritation of the eyes, nose, and throat 
as well as  difficulty breathing. Some mice developed 
asthma-like reactions. We also found altered posture, altered gait, 
tremors, falling, and/or hyperactivity in some of the mice 
exposed to these fumes. 

These effects occurred at concentrations similar to the 
concentrations of marker fumes about 12 inches 
from a pen in use, that is about the distance between the pen 
and the nose of a user.

The data demonstrate that many brands of felt tip markers 
release toxic (poisonous) chemicals into the air.  All the 
markers which we studied were clearly labelled "non-toxic." 
Don't believe labels.