9/15/98

A solution of 10g UA in 15mls H2O was measured with a Geiger counter. >500

counts/sec was generated.

A supplier had measured 100g UA :-

1 Alpha - <2 counts/sec, using a 540 scintillation meter with AP-2 Probe

2 Beta - >500 counts/sec, using a 540 E1 probe coupled to a GM Meter (this

determines beta events and some low energy gamma events)

3 Gamma dose Rate (energy field) - two measurements done:

using Mini monitor tpye R with GM Probe - 0.6mR/hr (mainly gamma)

and Ionisation chamber DMM 95/0500 - 5 mR/hr (Beta and Gamma energy

field).

4 Specific Activity (U approx. 55%) = 1.04 x 10 <<...>> Bq <<...>> gm

<<...>> .



Can UA be used openly without protection in laboratory?



Josephine <<...>>

michowej@nus.edu.sg

The concentration quoted is far higher (btw at what

concentration in water does UA become a saturated solution?)

than normally would be used for EM staining.



> A solution of 10g UA in 15mls H2O was measured with a Geiger counter.



I have been using UA for many years and I recall that whenever I

questioned and investigated its possible radiation implications

I have been assured that it is not dangerous at the

concentrations and quantities we use, provided that it is not

ingested.

Robin H Cross

Director : EM Unit, Rhodes University, Grahamstown, South Africa

eurc@giraffe.ru.ac.za - tel: +27 46 603 8168 - fax: +27 46 622 4377

http://www.ru.ac.za/affiliates/emu/em.htm



I calculated approximately the expected activity from 30 g UA

(about 0.1 mole, or 6*10^22 atoms). T_1/2 is 4.4*10^9 y and there are

3.1*10^7 s/y, so the decay rate is 5*10^-18 s^-1, and the activity is

3*10^5 Bq.

The build-up of daughter products with shorter half-lives will

reach steady state at which point the activities of the daughters will be

the same as that of the parent. Pa 234 has a gamma transition, and there

are several betas in the chain. The longer-lived isotopes in the chain

have lives of 10^4 to 10^5 y, and these will not be at steady state (unless

your UA is *very* old ;-) ). 0.6 mR/hr is a significant amount of exposure,

and, if one were to hold the jars for some minutes, a sizable fraction of

the allowed annual dose would be attained.



> Can UA be used openly without protection in laboratory?

> Small amounts can be used, but be sure to wash hands before eating.

One area of the lab should be used for UA. A quiet area with little traffic

is best. UA, while not nearly the most dangerous EM reagent, should still

be treated with respect.

Yours,

Bill Tivol

tivol@wadsworth.org

The saturation point is about 5%.









Ann Fook Yang

EM Unit

Eastern Cereal and Oilseed Research Centre

Agriculture and Agri-Food Canada

960 Carling Ave

Central Experimental Farm

Ottawa, Ontario

Canada K1A 0C6



Tel.: 613-759-1638

Fax: 613-759-1701

e-mail:yanga@em.agr.ca



>>> "ROBIN CROSS" <EURC@giraffe.ru.ac.za>

Well....

The Nuclear Regulatory Commission limits of skin & extremity

(hands, feet) is 50 Rem per year. ...Not something to "shoot" for,

since the dose is also limited to "As Low As Reasonably

Achievable".

The (damage) conversion coefficient from mR from this source (no

alpha if not ingested) to mRem is ~1. 50 Rem = 50,000 mRem. At a

dose rate of 0.6 mR/hr, one would have to hold the container for

many years to receive a one year maximum dose (50,000 / 0.6 per hr

= max hours exposure). At 5 mR/hr, it would be 50,000 / 5. At that

one would have to hold the container for 10,000 hours before

exceeding NRC dose limits. Exposure will also decrease as a

function of the square of the distance from the source.

For medical tests to discover any changes in body chemistry, it

would take about 50 Rem acute whole body exposure.

Less dose is always better, but in realistic terms the dose from

the UA should not be of any concern. If this level is of concern,

do not fly in airplanes, live at high elevations, avoid all medical

radiation, avoid certain beaches, beware of granite buildings, run

from radium dial watches, etc. :)

The real danger is if the UA enters the body where the alpha source

is in direct contact with livings tissue. Radiological bio-assay

(urine/fecal) would be required to detect this.

Woody White

McDermott Technology

Woody.N.White@mcdermott.com

Dear all,

in our TEM-Lab runs a discussion about the use of uranylacetate in routine

secion-staining because of its radioactivity and the possible risk of cancer.

We are wondered about the relative 'light' safety instructions for handling and disposal

uranylsolutions compared to that for C-Isotopes used in special enzymatic reactions.

1.Is this risk negligible , if not, what intern al safety instructions exists in other labs or is

literature about the risk of uranylacetat in biological labs available?

2.Has anybody experience with alternative (non-radioactive) counter stains?

Bernward Laube

University of Bielefeld

Faculty of Biology

Department Plant Morphology and Cell Ultrastructure

Universitätsstrasse 25

Germany 33615 Bielefeld

phone: 0521 1065592

fax: 0521 1066039

e-mail: b.laube@biologie.uni-bielefeld.de

http://www.uni-bielefeld.de/biologie/Pflanzenmorphologie/abt.1htm#ws

A qualified yes. The amount of activity is very low, and U is an

alpha-particle emitter. The range of the alphas is less than the thickness

of the dead layer of skin, so UAc is not a radiation hazard if one gets it

on ones hands, etc. However, alpha emitters can be extremely hazardous if

they are inhaled or ingested, so precautions should be taken so that small

droplets are not produced, and always wash your hands after using UAc.



> if not, what intern al safety instructions exists in other labs or is

> literature about the risk of uranylacetat in biological labs available?



Your safety office should have info on internal procedures; these

can vary from place to place. In the US we can get a materials safety data

sheet (MSDS) for any substance, and this will give info about hazards, re-

strictions for transport and use, etc. I'm sure any of the local EM sup-

pliers can get this for you.

Yours,

Bill Tivol

tivol@wadsworth.org

It seems most of the avid writers are conferencing, so here

is my contribution:

This forum has dealt with UA safety several times before.

It is, however, very time consuming to go through a year of

the archives, so here are is my summary/opinion.



1 All elements above lead in the periodic table are

radioactive.

2 Carbon, phosphorus and other isotopes are readily

absorbed and incorporated in tissues. That makes these

"biological isotopes" more dangerous.

Uranyl Acetate is water soluble and is not stored in the

body.

3 Whereas in mining, the insoluble Uranium particles are

lodged in the lung and emit radon gas for many years and

this makes insoluble U compounds a much greater

radiological hazard.

4 UAs' chemical toxicity is greater than its radiation

hazard - just don't ingest that stuff, it's a powerful

kidney poison, but happily not cumulative.

5 In general terms, the higher an element on the periodic

table, the more intense the electron "staining". A good

argument for lead, being the last non-radioactive element,

except that it a cumulative toxin, but we use it with care

(I trust). Actually I have seen lead pigments used in an

industrial setting (36 yrs ago), truly hair raising by

today's standards, but it was known then that lead was a

cumulative poison.

6 The (Edelmetalle) Au, Pd, Pt, Ir would seem attractive

alternatives for electron staining, but they are

non-reactive and only useful as markers or in evaporation

techniques.

7 Dense, high molecular number compounds have some staining

effects, for instance Sudan Black to show lipids, but these

stains are not nearly as effective as are the high atomic

number elements.

8 I am worried why so many people are worried. You would

have cause if you were dealing with the 200 litre drum

quantities of U "yellowcake", which has very similar

toxicity and radioactive attributes.

9 Consider: You are in a laboratory with fumehood and

gloves available, you are rather more knowledgeable about

these matters then armies of industrial workers and you are

using tiny quantities.

10 On balance I would suggest that it is rather more

dangerous to fly at high altitudes because of the gamma

radiation and it's a terrible thing to eat steak, because

of the high fat content and any scorched parts are

carcinogenic.



If you handle in a laboratory setting UA prudently, it is

in my opinion one of the less hazardous encounters in life.

I suggest that even a walk in the Teutoburger Wald, not to

mention urban Bielefeld is not without its dangers.

Cheers

Jim Darley

ProSciTech Microscopy

PLUS

PO Box 111, Thuringowa QLD 4817 Australia

Phone +61 7 4774 0370 Fax: +61 7 4789 2313

Great microscopy catalogue, 500 Links, MSDS, User Notes

www.proscitech.com.au

Would anyone know details of suppliers where Uranyl acetate can be obtained

already in solution i.e. a saturated solution in 50% ethanol. We previously

made this up ourselves from dry powder and ethanol, but we are trying to

reduce the potential hazzard to health by purchasing ready made solution.

Thanks on advance

Orla O'Shea, Dept of Anatomy, QUB

o.oshea@qub.ac.uk

Reichert makes an automatic grid stainer that uses prepared stains (called

the "Ultrostainer"). Maybe they would be a potential supplier for premixed

uranium stains.



Bob Wise

wise@vaxa.cis.uwosh.edu

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