Brian,
Very informative. Some folks don't like hearing the truth, even if ignoring it leads to their demise.
About 6-8 years ago I was looking into a new cleaner and nPB was one of the choices. After consulting with the members of Technet, including Brian, I steered clear of nPB products.
Thank you Brian.
Phil Nutting
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
Sent: Saturday, December 15, 2007 3:37 AM
To: [log in to unmask]
Subject: Re: [TN] ABZOLV
OK, on the whole, your attachment is pretty fair and covers a lot of the
problem with nPB. However, there is one grave error in it. It states the
ACGIH is an official level. This is not so, it is a recommendation by an
NGO, although one that should be taken seriously. Only OSHA PEL's have
the force of regulatory status in the USA and, as far as I know, OSHA
have not made any regulation regarding nPB.
A very early warning is contained in Sclar 1999:
Encephalomyeloradiculoneuropathy following exposure to an industrial
solvent, G. Sclar, Clin Neurol Neurosurg 101:199-202 (1999) and
describes the case of a youth who virtually lost the use of his right
arm after exposure to nPB. It is speculated that the protective gloves
he was using did not offer sufficient protection and the transdermal
uptake was sufficient to cause severe neuropathic conditions in the hand
and arm. This was the first reported human neuropathy. Other cases have
since been reported, including one where nPB was used as the solvent in
adhesives used to make aircraft seats. The workers were exposed to
massive vapour levels, peaking at >300 ppm, and several of them had
sequelae.
I was mandated by a company using nPB for cleaning PCB assemblies. Their
equipment was well designed and the background levels were down to the
extremely low 3 ppm in the workshop. However, the inspection/retouch
operators complained of headaches after the switch from CFC-113 to nPB.
It was speculated that, although the background level was low and the
assemblies were vacuum dried, there was sufficient nPB vapour trapped in
and under the components, especially wound coils, close to the
operator's faces, to cause problems.
I was co-chair of the UNEP Technical and Economic Assessment Panel nPB
Working Group and I made a presentation to the Parties to the Montreal
Protocol and my concluding remarks were:
"With our current knowledge, the prudent course is to use the
precautionary principle:
- Do not use nPB where a better-known, non-OD, solvent will work
- If it must be used, reduce emissions to the absolute minimum and
ensure minimum operator exposure.
- Err on the safe side"
Of course, this was based more on the fact that nPB is ozone-depleting,
rather than toxic.
My 2003 report to the Parties concluded:
"1.10 Conclusions
i. The forecast global expansion of the nPB market has not yet occurred,
because of the unclear regulatory situation, the current economic
position and geopolitical tensions.
ii. The bulk price of nPB, both raw and blended, has dropped to a level
more acceptable for general degreasing operations.
iii. The global production capacity of molecular nPB and blended
solvents has expanded considerably and can meet foreseeable immediate
demands once the regulatory and economic barriers are removed. Bromine
production capacity is sufficient that more nPB can be produced at
fairly short notice, if needed.
iv. nPB manufacturers and blenders are heavily promoting their products
as replacements for non-ozone-depleting chlorinated solvents, exploiting
possible regulatory loopholes.
v. The pharmaceutical, agrochemical and speciality chemical industries
consume about 5,000 tonnes of nPB annually. The emissions from these are
unknown.
vi. There is very evident increased interest in the use of nPB in
Article 5(1) countries, notably in the Peoples' Republic of China.
vii. Although there is no new information about the reproductive
toxicity and neurotoxicity of nPB, there are grounds for grave concern
with the incomplete toxicity or epidemiological information already
available.
viii. Recommended safety practices regarding the use of nPB are not
always being observed, resulting in excessive emissions and potential
over-exposure of operators. In particular, more attention must be paid
to the risks of dermal uptake, which may be more rapid in humans than
was thought.
ix. In view of the still-unknown toxicology, epidemiology and risk to
the ozone layer, Parties are urged to adopt the precautionary principle
and to discourage use of nPB in solvents applications, except where it
can be shown that no non-ozone-depleting solvent or process is suitable
and provided that every measure is taken to protect the operators from
any risk of undue exposure and to minimise emissions."
Personally, I believe the ACGIH recommendation of a 10 ppm time-weighted
exposure level probably presents little risk to operators, although the
French ATOFIN recommendation of 5 ppm would be better. I discount the
(proposed or promulgated?) Californian regulation of 1 ppm as being too
restrictive and unnecessary. However, can 10 ppm be easily maintained?
In very expensive and properly maintained/operated zero-emissions
machines, probably. I measured 15 ppm round such a machine in China, but
it had a minute leak. I measured 200 ppm round another similar machine
in Egypt, but the operator removed the cleaned goods before the vacuum
extraction had finished its work. I doubt whether it is possible in any
open-top vapour degreaser, even with deep refrigerated freeboards. It
may just be possible if the assemblies are kept in the freeboard of a
very modern machine for at least 30-60 minutes but this cannot be
guaranteed and is hardly conducive to a good throughput.
BTW, I'm not liked in your country because the Dead Sea Bromine Corp is
one of the major producers of nPB and my recommendations have been
largely negative!!!
Finally, I have a web page on the matter at
http://www.cypenv.org/worldenv/files/npb.htm
Brian
Gabriela Bogdan wrote:
> Thank you Brian.
> I found several materials on the internet, some contradicting each
> other, but this one frightened me.
> See attachment.
> Gaby
> ----- Original Message ----- From: "Brian Ellis" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Friday, December 14, 2007 7:05 PM
> Subject: Re: [TN] ABZOLV
>
>
>> The main component is n-propyl bromide. It depletes the ozone layer
>> and there is evidence of reproductive toxicity and neurotoxicity.
>> Because of the toxicity, various suppliers recommend operator exposure
>> levels varying from 5 to 100 ppm. I could provide references tomorrow,
>> if required.
>>
>> Brian
>>
>> Gabriela Bogdan wrote:
>>> Is anybody cleaning assemblies with ABZOLV?
>>> Do you know what the health hazards are?
>>> Gaby
>>>
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