PLB
I responded to the idea of potential harm by OA with several resources. It seems logical that if OA is harmful by one route, it might be harmful by others. Most of the responses by individuals have been anecdotal.
On this subject, Peter and I can agree.
My Handbook of Environmental Data on Organic Chemicals lists documented toxicity by cell multiplication inhibition at relatively low, mg/l levels for bacteria, algae, protozoa, with perturbations seen at mg/l for some arthropods, protozoa, worms, mollusca, insects. Fish seem to be less susceptible, with 20 mg/l being reported as LD0.
OSHA stipulates that the applicator shall follow OSHA respirator regulations found in 29 CFR 1910.134 or European Standard EN 149.
Use a NIOSH/MSHA or European Standard EN 149 approved respirator if exposure limits are exceeded or if irritation or other symptoms are experienced.
EPA's label implies that a paper dust mask is adequate. This is not what OSHA, NIOSH, or MSHA state. Others may argue that a paper (dust) mask this is ok for drip, and I'd say, that with the liquid, eye protection may be a bigger concern - drops of acid in the eye are less than pleasant.
For the fumes from vaporization, I require my employees and students to wear a properly fitted respirator.
Look at what we're now learning about deaths from vaping where a leading hypothesis is that maybe the oils are vaporized, get deep into the finest parts of the lungs, then congeals. I don't know whether oxalic does this in human lungs, but I'm not volunteering to be the guinea pig.
The Ontario beekeepers site warns: Oxalic acid is toxic (to humans) because of its acidic and chelating properties. It may cause burns, nausea, severe gastroenteritis and vomiting, shock and convulsions. It is especially toxic when ingested. (I've found records of 5 gms being lethal).
About inhalation the MSDS states: (Note: IDLH = Immediately Dangerous to Life and Health) "Revised IDLH: 500 mg/m3 [Unchanged]"
Basis for revised IDLH: No inhalation toxicity data are available on which to base an IDLH for oxalic acid. Therefore, based on acute oral toxicity data in humans [Webster 1930] and animals [Flury and Zernik 1935], the original IDLH for oxalic acid (500 mg/m3 or 92 ppm) is not being revised at this time.
Just above this statement is a warning that 30 minute exposure to the vapor may be lethal. Fortunately, I don't know of anyone who could stand 30 minutes of inhaling oxalic at this concentration, even a slight whiff burns my nose and eyes. Most of us can attest to it being a strong irritant.
Oxalic acid is a poison and human harm to humans and death have been documented. Recovery may take months.
Let's take the 'harmless' statement with some caution.
Jerry
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