Mixed Xylenes
Environmental Sources
Xylenes exist in ambient air as a mixture of ortho, meta and para isomers.
Sources of xylenes include: motor vehicles, aircraft, petroleum refineries
and terminals, service stations, lawnmowers and other petrol-fuelled implements,
chemical manufacture, polyester manufacture, manufacture and use of paints,
dyes, and lacquers, wood burning stoves and fireplaces, crop residue and
forest management burning, bushfires, coal tar, petroleum and emissions
from plants.
Human Health effects
Short-term exposure of people by inhalation to high levels of xylene
can cause irritation of the nose and throat; gastrointestinal effects
such as nausea, vomiting and gastric irritation; mild transient eye irritation
and neurological effects. Long-term inhalation exposure to mixed xylenes
results primarily in Central nervous system effects such as headaches,
lack of muscle coordination, dizziness, confusion, and changes in one's
sense of balance. Other effects include laboured breathing, decreases
in lung function, heart palpitations, severe chest pain and possible effects
on the blood and kidneys.
Most of the information on long-term exposure to xylenes is from studies
of workers employed in industries that make or use xylenes. Those workers
were exposed to levels of xylenes in air far greater than the levels normally
encountered by the general population. Many of the effects seen after
their exposure to xylenes could have been caused by exposure
to other chemicals that were in the air with xylene. There is not sufficient
data to determine whether exposure to xylenes cause developmental or reproductive
effects or cancer in humans.
Exposure limits
- The ACGIH (American Conference of Governmental Industrial Hygienists)
set a TLV of 100 ppm (TWA) which is 434 – 435 mg/m3, a STEL
(Short Term Exposure Limit) of 651 - 655 mg/m3 (15 minutes).
Sources and links:
www.nepc.gov.au/pdf/Issues_Paper_air.pdf
www.horizononline.com/MSDS_Sheets/825.txt
www.lpe.nt.gov.au/enviro/POLDOC/npi/Total.htm
www.watoxics.org/tkiaq.htm
www.modcon.co.il/exposure.htm
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