You Have Safety Questions? We Have
««« By the STAO Safety Committee
The STAO Safety Committee welcomes enquiries, with respect to safety
issues, from STAO members. Please send your questions to the Safety Committee
Chair (refer to page 4 ‘Committee Chairs’). Your questions
and the STAO Safety Committee responses may be published in Crucible,
particularly if the information is deemed of general interest to other
STAO members. Anonymity, however, will be guaranteed
What level of exposure to methylene blue is harmful to students/teachers
with G6PD deficiency? I’ve used this substance as a biological
stain for more than twenty five years, but it wasn’t until this
September, when a colleague had a student with this disorder enrolled
in their class, that I realized that exposure to it can cause hemolytic
anemia in persons with G6PD deficiency.
RESPONSE: G6PD is glucose-6 phosphate dehydrogenase deficiency.
It’s X-linked hereditary and fairly common, 400 million people
world-wide. It causes life-long anaemia which is mild in most people,
but can become severe to the point of destroying red blood cells and
can cause severe jaundice. Usually a
trigger is required for an attack of acute anaemia. Methylene blue
is an agent that can exacerbate G6PD.
However, problems with G6PD arise from injection or ingestion of something
that aggravates the condition. The effect of methylene blue is on red
blood cells, so as long as there’s no contact with the blood stream
(mucus membranes, etc.) there is no risk. In fact methylene blue is injected
to treat something called methaemoglobinaemia, a cyanosis
sometimes found in premature infants and people exposed to industrial
chemicals, especially cyanides. This is done immediately, and only
if there is a reaction afterwards is G6PD tested for and blood transfusions
are then used to correct the anemia.
Since the problem only occurs if there is direct injection or ingestion,
safety should not be a concern in general lab usage as long as adequate
care is used.