This slow time-course does not sound like either acid; certainly not conc. sulfuric. The lack of visible contamination on the gloves is suspicious. The slow growth generalized irritation/necrosis is suspicious.
How about the wastewater the lab was studying. Getting a small splash is not threatening, after, "it's just water."
The circumstances could easily bias the Dx toward chemical, when if fact, it is microbiological.
I think there are way to many unknowns to do more than speculate, and it is too late to get a verifiable determination
Work safely - the skin you burn may be your own!
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From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> On Behalf Of ILPI Support
Sent: Wednesday, November 6, 2019 10:43 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] delayed acid burn
Of course, the assumption thus far is that the burn is related to these two chemicals. In a laboratory, you can be exposed to all sorts of other substances and not realize it.
While Occam's razor is probably correct here, it's important to keep other potential causes in the back of your mind.
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In my experience, concentrated sulfuric will give you a stinging sensation followed by itching within seconds of exposure. If you don't do a good job at decontaminating your skin, then you can have a delayed sensation. However, it will be within the hour.
SYMPTOMS: Exposure to this compound may cause irritation of the skin, eyes and mucous membranes and may lead to contact dermatitis or severe burns.
ACUTE/CHRONIC HAZARDS: This material is capable of causing severe burns. (NTP, 1992)
SKIN: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. IMMEDIATELY call a hospital or poison control center even if no symptoms (such as redness or irritation) develop. IMMEDIATELY transport the victim to a hospital for treatment after washing the affected areas.
So, there may be a delay with this chemical.
I'm not an IH specialist, but looking at the SDS's for the acids, if the student got some sulfuric acid on the back of their glove and didn't realize it (nitrile break through is 30 minutes), it seems plausible it soaked through and cause a burn. Of course, if the glove had been compromised and leaked in through a break, the glove would just hold it against their skin.
One also wonders if there was acid used/spilled outside the area they were expecting it and managed to contaminate themselves when they were not wearing any gloves.
From Sigma's SDS (Sulfuric acid):
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.2 mm
Break through time: 30 min
Material tested:Dermatril =AE P (KCL 743 / Aldrich Z677388, Size M)
From Sigma's SDS (Iodic Acid):
Full contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril =AE (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril =AE (KCL 740 / Aldrich Z677272, Size M)
Asking this question on behalf of a colleague from another university (so if there are follow-up questions, there may be a communications delay in answering them):
What kinds of delayed reactions are known for iodoacetic or concentrated sulfuric acid?
A graduate student was working with concentrated sulfuric acid to acidify wastewater (wastewater treatment plant effluent) samples, and spiking them with iodoacetic acid (small quantities, since it was a spike). An experienced student, who had done this before , she was wearing nitrile gloves (the typical disposable type). To the best of her knowledge, she had no skin contact with the chemicals she was using and used proper glove removal technique.
Approximately a day or so later, she noticed a blistered looking patch on the back of her hand, near the joint of the thumb and first finger bones - about the size of a nickel. It spread, and by about four days after the presumed exposure, covered approximately half of the back of the hand. On-campus medical referred to a more experienced doctor, who ended up referring the student to a hospital with burn expertise (including chemical burns). The campus EH&S felt the response was due to the sulfuric or maybe the iodoacetic acids; the hospital agreed it looked like a chemical burn. The assumption is that acid penetrated the gloves or fell off the gloves onto skin during removal.
Treatment ended up including cadaver skin transplant; the student seems to be recovering well and doing fine. However, all involved would like a better understanding of what might have happened.
Information related to the question above, or other ideas as to what else you might consider checking for possibilities, is welcomed.
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