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Beryllium Monoxide Toxicology


Identification :
 
CAS number : 1304-56-9
UN number : UN1566
Molecular formula : BeO
Molecular weight: 25.01
 
Main Synonyms:
 
French Names :
Oxyde de béryllium
Oxyde de glucinium (old appellation)
English Names :
Beryllia,
Beryllium oxide,
Beryllium monoxide.
 
Uses and Sources of Emission :
-in ceramics,
-in electronics and micro-electronics,
-in the manufacture of glass,
-as chemical catalyst,
-as regulator in nuclear reactors,
-as refractory material in the metallurgy of rare earths,
-in high power laser tubes,
-in microwave telecommunication systems and as components of microwawe ovens,
-in windows of X-ray transmitters used under extreme conditions,
-etc.
 
Hygiene and Safety :
 
I-Appearance :
Beryllium oxide is a solid crystal or a fine amorphous, white and odourless powder according to the heat treatment at the time of preparation.
 
II-Physical Properties :
 
Odor : None
Color : White
Physical State : Solid
Melting Point (F) : 2547 (BeO)
Solubility (BeO) : None
Density (g/cc) : 2.86 (BeO)
 
III-Inflammability :
This product is non flammable.
 
IV-Explosiveness :
Heating of beryllium oxide with magnesium powder can cause an explosive reaction.
 
V-Techniques and Means for Extinguishing Fire :
Use any means appropriate for the surrounding materials.
Special techniques:
Beryllium monoxide released from a beryllium fire is very toxic: wear an autonomous respiratory protection gear and protective clothing covering all of the body.
After a beryllium fire, decontamination must be carried out by qualified personnel.
 
VI-Products of Combustion :
Beryllium oxide does not burn
 
Prevention :
 
I-Protection Means :
When engineering measures and modifications of working methods are not sufficient to reduce the exposure to this substance, the wearing of an individual protection apparatusr can be necessary.
These protection gears must be in accordance with the regulation.
 
II-Respiratory Protection :
In the presence of powder or dust of beryllium oxide, wear a respiratory protection apparatus if the concentration in the work environment is higher than the action level and even when the exposure is lower than this one.
 
III-Skin Protection :
Wear skin protection. The choice of a skin protection gear depends on the nature of the work to carry out. In the presence of powder or dust of beryllium oxide, wear protective clothing covering all of the body.
 
IV-Ocular Protection :
Wear ocular protection. The choice of an ocular protection gear depends on the nature of the work to carry out and, if it is necessary, of the type of respiratory protection gear used.
 
Reactivity :
 
I-Stability :
This product is stable under normal conditions of use.
 
II-Incompatibility :
Heated in the presence of magnesium, it reacts violently and can produce an explosion.
 
III-Decomposition Products :
None, this product is stable even at its melting point (2 530 °C).
 
Handling :
 
I-When possible, use substitution products having less harmful effects, or a wet process.
II-Avoid any operation or process which can produce fine particles or a cloud of dust.
III-Favour containment of processes, consider and install aspiration at the source.
IV-Reduce the number and the surface of the areas where there is a risk of exposure to beryllium and its compounds, just as the number of workers having access to these areas.
V-Use high efficiency filter vacuum cleaners against particles (HEPA) to clean the equipment and the floor of the working area.
VI-Avoid any skin and ocular contact.
VII- Do not eat and do not drink while using this product.
VIII-Observe very strict personal hygiene. Wash and change clothing after work.
IX-Completely separate town and working clothes (Double locker). Protection gears and working clothes including shoes, should not leave the workplace.
X-Double lockers should be available to workers, one for work clothes, the other for personal clothes.
 
Storage :
Store away from places where fire hazards are high, away from incompatible products, in a cool and well ventilated place. Moreover, if the product is in the form of powder, store in a tight container, well identified.
 
Leaks :
 
I-Because of its toxicity, every precaution must be taken to avoid a leak or a spill of this product.
II-If the product is used as particules or if there is dust, establish a limited access zone and limit access until cleaning is completed. Cleaning should be carried out only by qualified personnel.
III-Do not touch damaged containers or leaked products without wearing protective clothing covering all of the body and an autonomous respiratory protection gear.
IV-Prevent the formation of clouds of dust.
V-Collect dust by using a wet process or a high efficiency filtering vacuum cleaner against particles (HEPA).
VI-Collect in a hermetic container duly identified by using a suitable technique in order to prevent the contamination of the area.
 
Waste Disposal :
 
This product should not be dispersed into the environment. Beryllium oxide wastes in the form of powder or dust must be recovered in a sealed container identified and handed over to a firm which recycles it. If necessary, consult concerned regional authorities.
 
Toxicology :
 
I- Toxicokinetics :
 
A-Absorption :
 
1-Pulmonary Absortion :
An exposure to airborne beryllium in excess of the occupational standard can occur :
A-When powdered beryllium oxide is handled.
B-In metallurgy, if beryllium-containing materials are melted or casted and at the time of handling of slags and scum.
C-When abrasive cutting, machining, grinding, sanding, polishing or crushing pieces containing beryllium oxide.
D-When heat treating metal pieces containing beryllium or at the time of any process implying heating, such as welding or cutting with a blowtorch.
E-At the time of maintenance, cleaning or repairing equipment contaminated such as furnaces, tanks or boilers in sectors such as petroleum, metallurgy or energy.
F-When sorting, handling or recycling electronic parts intended for recovery.
G-Volatile beryllium hydroxide can be formed when firing solid BeO parts at temperature greater than 900 oC in a moist atmosphere such as in a hydrogen atmosphere sintering furnace.
 
a-Insoluble compounds :
The pulmonary clearance occurs very slowly. What was not eliminated quickly, by the mucociliary activity or phagocytosis of the particles, is retained several months in the lungs and is gradually released into the blood.
b-Soluble compounds :
The pulmonary clearance occurs quickly by dissolution in the pulmonary fluids and a variable proportion passes into blood.
c-Pulmonary clearance of low temperature calcined beryllium oxide would be faster than that of high temperature calcined beryllium oxide because of its greater solubility.
 
2-Skin Absorption :
Beryllium and its compounds are practically not absorbed through intact skin because they bind to components of the skin (proteins and nucleic acids) to form lowly diffusible complexes. However, it is thought that skin contact can especially play a part in sensitizing following exposure to fine particles.
 
3-Digestive Absorption :
Beryllium and its compounds are only very slightly absorbed by the digestive tract. The absorbed amount depends on the dose and the solubility of the compounds. This amount is limited by the formation of insoluble colloidal phosphates in the intestine.
 
B-Distribution :
Absorbed beryllium compounds, are transported in the body adsorbed on plasmatic proteins in the form of colloidal phosphate. In the short run, they tend to accumulate in the liver especially in the cases of important exposures. In the long run, one finds them mainly in the lymphatic ganglia and the bones. They were also identified in the blood of the umbilical cord and maternal blood.
 
C-Metabolism :
Beryllium and its compounds are not metabolized. In the lungs, soluble beryllium salts are partially transformed into insoluble salts.
The beryllium ion inhibits in a competitive way many enzymes activated by magnesium or manganese, in particular alkaline phosphatase.
The immunological action probably goes through the formation of a beryllium-protein complex, because of the small molecular weight of beryllium.
 
D-Excretion :
Compounds absorbed into the body are excreted mainly in the urine. Compounds which are not absorbed into the body are excreted mainly in the feces following ingestion by the oral route or by the pulmonary mucociliary clearance, and the excretion depends on the solubility of the ingested compounds.
Beryllium compounds have also been identified in mother's milk and colostrum.
Mobilization and excretion can continue during several years and persist a very long time after the cessation of exposure.
There is no obvious correlation between the presence or the severity of berylliosis and the urinary beryllium level.
 
E-Half-Life :
There are no precise data in human beings but, one can say that in general according to animal studies, the insoluble or not very soluble compounds and the soluble compounds, are cleared from the pulmonary tissue in a biphasic way initially with a half-life of a few days during which 30 to 50 % of the beryllium is eliminated.
The second phase which varies according to the solubility of the compounds suggests that the half-life of the soluble compounds is of about a few weeks or a month while it varies from months to years for the compounds which are little or not soluble.
The half-life in the whole body can be several years.
 
F-Biological Data :
An exposure to 2 µg/m³ of beryllium in the air corresponds to approximately 7 µg/L. in the urine and 4 µg/L. in the blood. For a non-professionally exposed population the urinary beryllium concentration is less than 0,9 µg/l.
The EPA (USA ) has estimated that the total amount of beryllium absorbed daily by the general population is 423 ng following the inhalation of ambient air and from the ingestion of food and water. The most important contribution comes from the ingestion of water (300 ng) and food (120 ng).
 
G-Sensitive Population :
Several studies suggest that genetic susceptibility can play an important role in the development of berylliosis. People suffering from chronic berylliosis are carrying more frequently than controls a genetic marker : (HLA-DPB1 Glu69). This allele would be present in 85 to 95% of the patients and in only 30 to 45 % of the controls.
 
II-Acute Effects :
 
A-Inhalation :
 
1-Acute Tracheo-Bronchitis :
It is benign and heals in one to four weeks.
2-Chemical Pneumonitis :
Ambient concentrations above 25 µg/m³ beryllium are usually associated with this acute form, but these exposures are rare nowadays.
It can occur within 72 hours after a massive exposure to low temperature calcined beryllium oxide. This was not reported following exposure to high temperature calcined beryllium oxide.
a-Symptoms :
The following symptoms were reported :
- cough,
- sensation of retrosternal burning,
- increasing dyspnea,
- effects on the general state resulting in :
* light fever,
* feeling of weakness
* tiredness,
- cyanosis.
b-Evolution :
It can be fulgurating with complications such as pulmonary oedema and fibrosis.
c-Prognosis :
Death :
Fatalities were reported.
Recovery :
Recovery occurs in 85 to 90 % of the cases. Convalescence can vary from 4 to 6 months.
Chronicity :
The acute form can also progress to the chronic form.
 
B-Skin Contact :
The incrustation of small crystals or chips of beryllium oxide under the skin can cause the formation of painless ulcers or subcutaneous granulomas after a few months.
 
C-Ocular Contact :
The damage can result from irritation by particles or by the mechanical action of dusts or of the particles. Exposure can result from the direct contact with airborne particles (particles, dusts, or powders), or following ocular contact with the hands or soiled clothing.
 
III-Chronic Effects :
 
Berylliosis :
 
A-Introduction :
Berylliosis develops in 2 to 15 % of workers exposed according to the kind of work carried out. The appearance and the progression of the disease are partly due to individual genetic susceptibilities which act in connection with the exposure.
 
B-Exposure :
Prolonged exposure, even to very weak beryllium concentrations or to its compounds can cause berylliosis. The low temperature (500°C) calcined beryllium oxide would be more sensitizing that the high temperature (1 000°C) calcined beryllium oxide because of its greater solubility.
 
C-Physio-Pathology :
The first action is inflammation which creates a ground favourable to the development of a cellular mediated immunological response. Beryllium acts in combination with peptides as a hapten which activates the effector cells to produce cytokins. These last ones stimulate the inflammatory and immunizing reaction of various pulmonary cells while acting on the development of the granulomatous inflammation associated with chronic berylliosis.
 
D-Latency :
It is an insidious disease which can appear a few months only after the beginning of the exposure or several years after the end of an exposure having lasted only a few months. Usually the disease appears within a delay varying from a few months to 5 years, seldom up to 20 or 30 years.
 
E-Stages of Chronic Berylliosis :
1-Sensitizing to Beryllium :
Demonstrated by two BeLPT abnormal tests,
2-Sub-Clinical Berylliosis :
A certain evidence of pulmonary effects, but without symptom,
3-Chronic Berylliosis :
Evidence of pulmonary effects with symptoms.
 
F-Symptomatology :
At the beginning :
-exertional dyspnea,
-dry and irritating cough, more severe in the morning or upon exertion, accompanied by chest pain and a feeling of tiredness.
In the more advanced cases :
-fever or night sweats,
-anorexia accompanied by a progressive loss of weight,
-articular pains.
One can also observe :
-cyanosis,
-digital hippocratism,
-enlargement of the liver and the spleen,
-adenopathy,
-cardiomyopathy
-renal effects.
The pulmonary effect is characterized by the formation of non-caseous granulomas accompanied by alveolitis. When the effect progresses, diffuse interstitial fibrosis settles.
 
G-Complications :
Complications can occur such as spontaneous pneumothorax and cardiopulmonary diseases.
 
H-Exacerbation :
The disease can be exacerbated by factors such as a re-exposure, infection, surgical operation, pregnancy, etc.
 
I-Evolution :
The evolution of the disease can occur in a gradual way, but can also be very variable.
Complete cure remains exceptional. A minority of people remains asymptomatic for long periods of time, while the majority presents symptoms, while carrying out an almost normal life.
The evolution of the disease can end in cardiorespiratory insufficiency (cor pulmonale) causing death in the most advanced cases.
 
J-Conditions Aggravated by Exposure :
People with deteriorations of the pulmonary function, airway diseases, or conditions such as asthma, emphysema, chronic bronchitis, etc can incur more deterioration if dust or vapors are inhaled.
If former diseases or damage to the neurological, circulatory, hematologic, or urinary systems have already occurred, suitable sreening examinations should be carried out in individuals who can be exposed to hazards when handling and using this material
 
K-Medical Surveillance :
 
1-Biological Monitoring of the Exposure :
 
A- Beryllium lymphocyte proliferation (BeLPT) :
-As a monitoring blood test, it is more sensitive than clinical evaluation and has a great predictive value in spite of its limitations.
-When it is performed on cells coming from bronchoalveolar lavage, the predictive value is nearly 100 % of the cases, but this test is less frequent because the sampling requires a more invasive procedure.
-A negative test does not exclude the possibility of sensitization or berylliosis, particularly in smokers.
-The BeLPT test can help to make the distinction between berylliosis and other pulmonary diseases, particularly sarcoidosis.
-The use of BeLPT as a test for berylliosis monitoring has identified a population of workers sensitized without apparent symptom of the disease. These sensitized workers had pulmonary function tests, a tolerance to exercise, pulmonary X-rays and biopsies that were normal.
In this type of situation, these cases must remain under medical supervision and be re-examined at regular intervals to detect the first signs of the disease. It is estimated that annually, approximately 10 % of the sensitized individuals, will develop the disease.
 
B-Periodicity :
Certain researchers mention that BeLPT monitoring should be conducted periodically among workers exposed to beryllium, every 2 to 5 years, according to the level of exposure.
 
C-Follow-up :
A medical follow-up must be performed in sensitized workers every 1 to 2 years and immediately in workers with subclinical impairment, or sensitized with symptoms or unexplained pulmonary disease.
 
2-Other Suggested Test :
Pulmonary radiography can identify a certain number of cases that the (BeLPT) missed, the blood test detecting about from 80% to 90% of the cases.
 
L-Treatment :
There is no treatment to cure berylliosis. However, certain drugs are effective to reduce the effects and to slow down the progression of the disease. The use of these drugs, usually corticosteroids, must be permanent.
For the sensitized or asymptomatic workers, the use of drugs is not necessary, but they must be the subjects of a medical follow-up in order to evaluate the progression of the disease.
 
IV-Skin Sensitization :
This product is a skin sensitizer. Several cases of dermatitis of the allergic type (eczema) were reported in workers exposed to beryllium and its compounds. These cases were confirmed by skin patch tests with several beryllium salts (sulphate, fluoride, chloride and others).
 
V-Pregnancy :
 
A-Effects on development :
It crosses the human placental barrier.
B-Effects on reproduction :
The available data do not make it possible to make an adequate evaluation of the effects on reproduction.
C-Data on breast milk :
It is found in the breast milk of animals..
 
VI-Cancerogenic Effects :
Human carcinogen confirmed by I.A.R.C., A.C.G.I.H., N.T.P.
 
VII-Mutagenic Effects :
The available data do not make it possible to make an adequate evaluation of mutagenic effects. The tests of DNA effects and of cellular transformation proved to be positive for low temperature calcined beryllium oxide whereas doubtful results were obtained in the same tests for high temperature calcined beryllium oxide.
 
First aid :
 
I-Inhalation :
In the event of inhalation of fume or dust, bring the person into a ventilated place and place him in a half-sitting position. If he does not breathe, give him artificial respiration. In the event of respiratory difficulties, give him oxygen.
Transfer immediately to the nearest medical emergency department.
II-Ocular Contact :
Rinse eyes with plenty of water during 5 minutes or until the product is removed.
If irritation persists, see a doctor.
III-Skin Contact :
Quickly withdraw contaminated clothing. Wash the skin with water and soap. Completely clean cuts or wounds. Any beryllium oxide particle lodged accidentally under the skin must be removed.
IV-Ingestion :
Rinse mouth with water.
See a doctor.
 
Quebec's Exposure Limit :
 
I-Valeur d'Exposition Moyenne Pondérée (VEMP) :
0,00015 mg/m³ (expressed as Be (Beryllium).
 
II-Notes :
C2 : A suspected human carcinogen.
EM : Exposure to this chemical must be reduced to the minimum.
RP : Substance whose recirculation is prohibited
 
References :
 
1-Occupational Medicine,Carl Zenz, last edition.
2-Clinical Environmental Health and Toxic Exposures, Sullivan & Krieger; last edition.
3-Sax's Dangerous Properties of Industrial Materials, Lewis C., last edition.
4-Toxicologie Industrielle et Intoxications Professionnelles, Lauwerys R. last edition.
5-Chemical Hazards of the Workplace, Proctor & Hughes, 4th edition.
6-CSST-Quebec, Répertoite Toxicologique.
7-ESPI Metals MSDS, 1996 (Prepared par S. Dierks)

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Edouard Bastarache M.D.
Occupational & Environmental Medicine
Author of "Substitutions for Raw Ceramic Materials"
Tracy, Québec, CANADA

edouardb@sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/~edouardb/




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