CHRONIC EXPOSURE- Inhalation of mercury vapor over a long period may cause mercurialism, which is characterized by fine tremors and erethism. Tremors may affect the hands first, but may also become evident in the face, arms, and legs. Erethism may be manifested by abnormal shyness, blushing, self-consciousness, depression or despondency, resentment of criticism, irritability or excitability, headache, fatigue, and insomnia. In severe cases, hallucinations, loss of memory, and mental deterioration may occur. Concentrations as low as 0.03 mg/m3 have induced psychiatric symptoms in humans. Renal involvement may be indicated by proteinuria, albuminuria, enzymuria, and anuria. Other effects may include salivation, gingivitis, stomatitis, loosening of the teeth, blue lines on the gums, diarrhea, weight loss, anorexia, speech and sensory disorders, unsteady gait, chronic pneumonitis and mild anemia. Repeated exposure to mercury and its compounds may result in sensitization. Women occupationally exposed have reported menstrual disturbances, reduced ovulation and an increased risk of spontaneous abortion. Intrauterine exposure may result in tremors and involuntary movements in the infants. Mercury is excreted in breast milk. Reproductive effects have been reported in animals.
FIRST AID- Remove from exposure area to fresh air immediately. Perform artificial respiration if necessary. Maintain airway, blood pressure and respiration. Keep warm and at rest. Treat symptomatically and supportively. Get medical attention immediately. Qualified medical personnel should consider administering oxygen.
Health Effects from Dental Personnel Exposure to Mercury Vapor
1. Dentists and dental personnel who work with amalgam are chronically exposed to mercury vapor.(1,6-12,32,34,36,72,122,123,124,171,172,173,240,249,253]
Studies note that carpeting in dental offices should be avoided as it is a major repository of mercury[188].
Mercury levels in urine of dental personnel average about 2 times that of controls(123,124,171,249) and was 43 nmol/liter for a population surveyed in Sweden(171), which is above the Swedish occupational exposure guideline.
2. Drilling old amalgam fillings with only a saliva extractor and no other precautions produces mercury vapor levels 2 to 15 times occupational threshold limit values(30 micrograms/cubic meter)[120,219].
3. The average dental office exposure affects the body mercury level approximately the same as having 19 amalgam fillings[123,124,173].
Dentists were found to score significantly worse than a comparable control group on neurobevaioral tests of motor speed, visual scanning, visuomotor coordination, concentration, verbal memory, visual memory, and visuomotor coordination speed(249,252,253).
4. Both dental hygienists and patients get high doses of mercury vapor when dental hygienists polish or use ultrasonic scalers on amalgam surfaces(240).
Pregnant women or pregnant hygienist especially should avoid these practices during pregnancy or while nursing since maternal mercury exposure has been shown to affect the fetus and to be related to birth defects, SIDS, etc. (38,61) and breast milk contains up to 6 times higher mercury than in the mother's blood(20).
5. Body burden increases with time and older dentists have median mercury urine levels about 4 times those of controls, as well as higher brain and body burdens(13,34, 70-74,122]. Some older dentists have mercury levels in some parts of the brain as much as 80 times higher than normal levels(14,34).
6. Dentists and dental personnel experience significantly higher levels of neurological, memory, musculoskeletal, mood, and behavioral problems, which increase with years of exposure(13,34,49,69-74,88,122,188,246,247,248,249,253]
7. Female dental technicians who work with amalgam have significantly reduced fertility and lowered probability of conception(3,24,38, 121], and their children have significantly lower average IQ compared to the general population(13). The level of mercury excreted in urine is significantly higher for female dental assistants than dentists(171,172,173,247). Several dental assistants have been diagnosed with mercury toxicity and some have died of related health effects(245,246,247,248).
8. Many homes of dentists have been found to have high levels of mercury contamination used by dentists bringing it home on shoes and clothes[187].
9. Some studies have found increased risk of lung, kidney, brain, and CNS system cancers among dental workers(14,34, 143].
10. Autopsies of former dental staff found levels of mercury in the pituitary gland averaged over 10 times that of controls(99), as well as higher levels in the occipital cortex and renal cortex and thyroid.
References
1. Sandra Denton MD; Proceedings of the First International Conference on Biocompatibility, 1988
3. Gordon - Pregnancy in Female Dentists- a Mercury Hazard. Proceedings of Intl conference on Mercury Hazards in Dental Practice Sept. 2-4 Glasgow 1981
6. Schulein,T.M.; Reinhardt, J.W. and Chan K.C. Survey of Des Moines area dental offices for Mercury vapour. Iowa Dent. J. 70(1):35-36 1984
7. Jones, DW, Sutton EJ, and Milner EL Survey of Mercury vapour in dental offices in Atlantic Canada.Can. Dent. Assoc. J. 4906:378-395, 1983
8.Miller, RW and Ochua;. Report on independant survey taken of Austin dental offices for mercury contamination. Texas Dent. J. 100(1):6-9, 1983
9. Kantor, L. and Woodcock C, Mercury vapour in the dental office- does carpeting make a difference? JADA103(9):402-407,1981
10 Skuba, A. Survey for Mercury vapour in Manitoba dental offices J Can. Dent.Assoc. 50(7):517-522, 1984
11. Chop, GF. and Kaufman, EG. Mercury vapour related to manipulation of amalgam and to floor surfaces.Oper. Dent. 8(1):23-27,1983
12. Roydhouse, RH. Ferg, MR. and Knox, RP. Mercury in dental offices J Can Dent Assoc 51(2):156-158, 1985
13. Butler, J. Proceedings from the First International Conference of Biocompatibility. 1988
14. Magnus Nylander, Mercury Concentrations in the human brain and kidneys in relaton to exposure from dental amalgam fillings ICBM 1988
20. Vimy, MJ,Takahashi,Y, Lorscheider,FL Maternal -Fetal Distribution of Mercury Released From Dental Amalgam Fillings. Dept of Medicine and Medical Physiology , faculty of Medicine, Univ of Calgary, Calgary Alberta Cannada
24. Brodsky, JB. Occupational exposure to Mercury in dentistry and pregnancy outcome. JADA111(11):779-780., 1985
32. Jonnes, Suttow and Milner. Survey of Mercury vapour in dental offices in Atlantic Canada, Canadian Dental Association Journal ., 49(6):378-395.,1983
34. Patrick St”rtebecker, Associate Professor of Neurology, Karolinska Institute , Stockholm.. Mercury Poisoning from Dental amalgam- a hazard to the human brain. Bio-Probe, Inc. ISBN: 0-941011001-1 & Neurology for Barefoot Doctors, Stortebecker Foundation for Research, 1988.
35. Hal Huggins. Its All in Your Head, 1994.
36. Sam Queen; Chronic Mercury Toxicity: New Hope Against an Endemic Disease.
Bio-Probe Books
38. Ziff S. and Ziff M. Infertility and Birth Defects: Is Mercury from Dental Fillings a Hidden Cause?, Bio-Probe, Inc. ISBN: 0-941011-03-8.1987
49. Amalgam Hazards - an assesment of research By Irwin Mandel DDS Assoc. Dean for Research School of dental and Oral Surgery Columbia University New York Published JADA Vol. 122 August 1991
61. Dr Gustav Drasch, Institute of Forensic Medicine, University of Munich. Public anouncement, 25 January 1994 Bio Probe March 1994; & "Mercury burden of human fetal and infant tissues", Euro.J. Pediatrics,153(8): Spring 1994, p607-610.
(69)D Gonzalez-Ramirez et al; "Uninary mercury, porphyrins, and neurobehavioral changes of dental workers in Monterrey, Mexico", J Pharmocology and Experimental Therapeutics,, 272(1): 264-274,1995
(70) N.J. Heyer et al, "Behavioral Effects of Low Level Exposure to HgO Among Dentists", Neurotoxicology & Teratology; 17(2):161-168(1995).
(71)S.C.Foo et al, "Neurobehavioral effects in Occupational Chemical Exposure", Environmental Research, 60(2): 267-273, 1993.
(72)D.L.Smith,"Mental effects of mercury poisoning",South Med J 71:904-5,1978.
(73)RT McNerney et al, "Mercury Contamination in the Dental Office: A Review", NYS Dental Journal, Nov 1979, p457-458.
(74) D.G. Mantyla et al, "Mercury toxicity in the dental office: a neglected problem", JADA, 92:1189-1194, 1976.
88) M.Godfrey et al, Confirmation of mercury retention and toxicity using DMPS", J Advance Med 7(1):19-30, 1994.
(99) M.Nylander et al, Mercury accumulation in tissues drom dental staff and controls", Swedish Dental Journal, 13:235-243, 1989.
(120) L.Pohl, "The dentist's exposure to elemental mercury during clinical work", Acta Odontol Scand,v53,n1,p44-48,1995.
(121)A.S.Rowland et al,"The Effect of Occupational Exposure to mercury vapor on the fertility of female dental assistants",Occup Environ Med, v55,n1,1994
(122) K.A.Ritchie et al, "Psychomotor testing of dentists with chronic low level mercury exposure", J Dent Res 74:420 IADR Abstract 160 (1995).
(123) I. Skare et al, "Mercury exposure of different origins among dentists and dental nurses", Scand J Work Environ Health, 16:340-347, 1990.
(124) I.Akesson et al, "Status of mercury and selenium in dental personel", Arch Environ Health, 46(2): 102-109, 1991 & J.Lenihan et al, "Mercury hazards in dental practice", British Dental J, 135:363-376, 1973.
(143) P.Boffetta et al, "Carciagenicity of mercury", Scand J Work Environ Health, 19(1):1-7,1993; & J Occup Med, 36(11):1260-64, 1994.
(171) A.Jokstad, "Mercury excretion and ocuupational exposure of dental personnel", Community Dent Oral Epidemio, 18(3):143-8,1990.
(172) B.Nilsson et al, "Urinary mercury excretion in dental personnel", Swed Dent J, 1986,10(6):221-32.
(173) D.Zanders et al, "Mercury exposure of male dentists, female dentists, and dental aides", Zentralbl Hyg Umweltmed, 1992,193(4):318-28.
(188)I.I. Ship et al, School of Dental Research, Univ of Penn., Mar 1983.
(219) D.E. Cutright et al, "Systemic mercury levels caused by inhaling mist during hig-speed amalgam grinding", J Oral Med 28(4):100-104,1973 ; & A.Nimmo et al, "Inhalation during removal of amalgam restorations", J Prosthet Dent, 63(2):1990 Feb, 228-33.
(240) K.W. Hinkleman et al, "Mercury release during ultrasonic scaling of amalgam", J Dent Res. 74(SE):131, Abstract 960, 1995; & C. Malmstrom et al,. "Silver amalgam: an unstable material", Swedish paper translated in Bio-Probe Newsletter, Vol 9(1):5-6, Jan. 1993.
(245) P.Lokken, "Lethal mercury poisoning in a dental assistant", Nor Tannlaegeforen Tid, Apr 1971, 81(4):275-288 & R. Wronski et al, "A csse of panarteritis nodoa assciated with chronic mercury poisoning", Dtsch Med Wohenschr, Mar 1977, 102(9):323-325.
(246) K.Iyer et al, "Mercury Poisoning in a dentist", Arch Neurol,1976, 33:788-790.
(247) N.Jacobsen et al, Oniv. Of Oslo Dental Faculty, "Profile ofwork-related health complaints among Swedish dental laboratory technicians", Community Dent Oral Epidemiol, 1996, Apr; 24(2):138-144.
(248) Y.Finkelstein et al, "The enigma of parkinsonism in chronic borderline mercury intoxication, resolved by challenge with penicillamine. Neurotoxicology, 1996, Spring, 17(1): 291-5.
(249) C.H.Ngim et al, "Chronic neurobehavioral effects of elemental mercury in dentists", Brithish Journal of Industrial Medicine, 1992; 49(11):782-790.
(252) K.Iyer et al, "Mercury Poisoning in a Dentist", Arch Neurol, 33:788-90, Nov 1976.
(253) K. Wesnes, Univ. Of Glasgow, "pilot study of the effect of low level exposure to mercury on the health of dental surgeons", Occupational & Environmental Medicine, 52(12): 813-17, Dec 1995 (England)
Title: Elevated T cell subpopulations in dental students.
Eedy D J, Burrows D, Clifford T, Fay A
J Prosthet Dent 63:593-596 (1990)
Abstract: "The absolute numbers of circulating white cells and lymphocyte subpopulations were studied in 25 final-year dental students and compared with a control group of 28 medical students. The total lymphocyte count, total T cell numbers (CD3), T helper/inducer (CD4), and T suppressor/cytotoxic (CD8) numbers were significantly elevated in the dental students as compared with the control group. There was no significant difference in the T helper/inducer killer cell (CD16) numbers between the study and control groups. Patch testing to mercury and mercuric compounds in both the study and control groups showed no evidence of cutaneous hypersensitivity to mercury. The reason for the observed elevations in T cell subpopulations in dental students is not clear. However, one possible explanation is the dental student's occupational exposure to mercury. Further work is underway tom examine this possible relationship and it is suggsted that dental personnel take adequate measures to reduce their exposure to mercury until the results of these studies are available."
From U.S. Department of Health and Human Services and U.S. Department of Labor
Occupational Health Guideline for Inorganic Mercury
Introduction
This guideline is intended as a source of information for employees, employers, physicians, industrial hygienists, and other occupational health professionals who
may have a need for such information. It does not attempt to present all data; rather, it presents pertinent information and data in summary form.
NOTE: These recommendations reflect good industrial hygiene and medical surveillance practices and their implementation will assist in achieving an effective occupational health program. However, they may not be sufficient to achieve compliance with all requirements of OSHA regulations.
The current OSHA standard for mercury is a ceiling level of 0.1 milligram of mercury
per cubic meter of air (0.1Êmg/m3). NIOSH has recommended that the permissible
exposure limit be changed to 0.05Êmg/m3 averaged over an eight-hour work shift.
The NIOSH Criteria Document for Inorganic Mercury should be consulted for more
detailed information.
Health Hazard Information
Routes of exposure
Mercury can affect the body if it is inhaled or if it comes in contact with the eyes or skin. It may enter the body through the skin.
Effects of overexposure
l. Short-term Exposure: Inhaled mercury vapor may cause headaches, cough, chest
pains, chest tightness, and difficulty in breathing. It may also cause chemical
pneumanitis. In addition, it may cause soreness of the mouth, loss of teeth, nausea,
and diarrhea. Liquid mercury may irritate the skin.
2. Long-term Exposure: Repeated or prolonged exposure to mercury liquid or vapor
causes effects which develop gradually. The first effects to occur are often fine
shaking of the hands, eyelids, lips, tongue, or jaw. Other effects are allergic skin rash, headache, sores in the mouth, sore and swollen gums, loose teeth, insomnia, excess salivation, personality change, irritability, indecision, loss of memory, and intellectual deterioration.
3. Reporting Signs and Symptoms: A physician should be contacted if anyone
develops any signs or symptoms and suspects that they are caused by exposure to
mercury.
Recommended medical surveillance
The following medical procedures should be made available to each employee who
is exposed to mercury at potentially hazardous levels:
l. Initial Medical Examination:
--A complete history and physical examination: The purpose is to detect pre-existing
conditions that might place the exposed employee at increased risk, and to establish
a baseline for future health monitoring. Persons with a history of allergies or known
sensitization to mercury, chronic respiratory disease, nervous system disorders, or
kidney disease would be expected to be at increased risk from exposure. Examination for any signs or symptoms of unacceptable mercury absorption such as weight loss, insomnia, tremors, personality changes, or other evidence of central nervous system involvement, as well as evidence of kidney damage, should be stressed. The skin should be examined for evidence of chronic disorders.
--Urinalysis: Since kidney damage has been observed in humans exposed to mercury, a urinalysis should be obtained to include, at a minimum, specific gravity, albumin, glucose, and a microscopic on centrifuged sediment. Determination of mercury level in urine may be helpful in assessing extent of absorption.
2. Periodic Medical Examination: The aforementioned medical examinations should be repeated on an annual basis.
Summary of toxicology
Acute exposure to mercury at high levels causes severe respiratory irritation,
digestive disturbances, and marked renal damage; chronic mercurialism, the form of
intoxication most frequently caused by occupational exposure, is characterized by
neurologic and psychic disturbances, anorexia, weight loss, and stomatitis. Skin
absorption of inorganic mercury probably adds to the toxic effects of vapor inhalation. Intraperitoneal injection of metallic mercury in rats has produced sarcomas. Exposure of humans to mercury vapor in concentrations of 1.2 to 8.5 mg/m3 causes cough, chest pain and dyspnea, leading to bronchitis and pneumonitis. Metallic
mercury readily vaporizes at room temperature, and the vapor has no warning
properties. At low levels, the onset of symptoms resulting from chronic exposure is
insidious; fine tremors of the hands, eyelids, lips and tongue are often the presenting complaint. Coarse jerky movements and incoordination may interfere with the fine movements considered necessary for writing and eating. Psychic disturbances such
as insomnia, irritability, and indecision occur; headache, excessive fatigue, anorexia, digestive disturbances, and weight loss are common; stomatitis with excessive salivation is sometimes severe; muscle weakness has been reported. Proteinuria may occur, but is relatively infrequent. Mercury has been reported to be capable of causing sensitization dermatitis. Examination of urine for mercury may be of value. There is no "critical" level of mercury in urine above or below which poisoning cannot be seen. Various observers have suggested from 0.l to 0.5 mg of Hg/l of urine as having clinical significance. Mercury, particularly organic forms, is known to adversely affect the fetus if the mother is exposed during pregnancy.
Chemical and Physical Properties
Physical data
1. Molecular weight: 200.6
2. Boiling point (760 mm Hg): 357 C (674 F)
3. Specific gravity (water = l): 13.5
4. Vapor density (air = 1 at boiling point of mercury): Not applicable
5. Melting point: -39 C (-38 F)
6. Vapor pressure at 20 C (68 F): 0.0012 mm Hg
7. Solubility in water, g/100g water at 20 C (68 F): 0.002
8. Evaporation rate (butyl acetate = l): Not applicable
Reactivity
1. Conditions contributing to instability: None
2. Incompatibilities: Contact with acetylene, acetylene products, or ammonia gases may form solid products that are sensitive to shock and which can initiate fires of combustible materials.
3. Hazardous decomposition products: None
4. Special precautions: Mercury can attack copper and copper alloy materials.
Flammability
l. Not combustible
Warning properties
l. Odor Threshold: Mercury is odorless.
2. Eye Irritation Level: Grant states that "when mercury metal droplets are in the epithelium, rather than the corneal stroma or anterior chamber, they are extruded rapidly with little reaction, as was reported in a patient who was sprayed forcefully with metallic mercury and was observed to have many fine silvery globules beneath the epithelium of the cornea. . .
"Mercury metal in contact with the conjunctiva has been shown in rabbits to be absorbed and ultimately to be detectable in the urine. While in contact with the conjunctiva, metallic mercury produced no clinical signs of conjunctivitis, but histologically an inflammatory reaction has been demonstrable. External contact with mercury vapor has repeatedly been observed to induce a characteristic discoloration of the crystalline lens (mercurialentis)."
Mercurialentis also is caused by systemic poisoning "from absorption of mercury vapor through the respiratory tract, the skin, and the gastrointestinal tract."
For the purposes of this guideline, mercury is not treated as an eye irritant.
3. Evaluation of Warning Properties; Mercury has no warning properties, according to the Hygienic Guide.
Monitoring and Measurement Procedures
Ceiling Evaluation
Measurements to determine employee ceiling exposure are best taken during periods of maximum expected airborne concentrations of mercury. Each measurement should consist of a fifteen (15) minute sample or series of consecutive samples totalling fifteen (15) minutes in the employee's breathing zone (air that would most nearly represent that inhaled by the employee). A minimum of three (3) measurements should be taken on one work shift and the highest of all measurements taken is an estimate of the employee's exposure.
Method
Sampling and analyses may be performed by collection of mercury with a three-section solid phase sampler, followed by analysis with an atomic absorption spectrophotometer. An analytical method for mercury is in the NIOSH Manual of Analytical Methods, 2nd Ed., Vol. 6, 1980, available from the Government Printing Office, Washington, D.C. 20402 (GPO No. 017-033-00369-6).
Respirators
Good industrial hygiene practices recommend that engineering controls be used to reduce environmental concentrations to the permissible exposure level. However, there are some exceptions where respirators may be used to control exposure. Respirators may be used when engineering and work practice controls are not technically feasible, when such controls are in the process of being installed, or when they fail and need to be supplemented. Respirators may also be used for operations which require entry into tanks or closed vessels, and in emergency situations. If the use of respirators is necessary, the only respirators permitted are those that have been approved by the Mine Safety and Health Administration (formerly Mining Enforcement and Safety Administration) or by the National Institute for Occupational Safety and Health.
In addition to respirator selection, a complete respiratory protection program should
be instituted which includes regular training, maintenance, inspection, cleaning, and
evaluation.
Personal Protective Equipment
Employees should be provided with and required to use impervious clothing, gloves, face shields (eight-inch minimum), and other appropriate protective clothing necessary to prevent repeated or prolonged skin contact with liquid mercury.
If employees' clothing may have become contaminated with mercury, employees should change into uncontaminated clothing before leaving the work premises.
Clothing contaminated with mercury should be placed in closed containers for storage until it can be discarded or until provision is made for the removal of mercury from the clothing. If the clothing is to be laundered or otherwise cleaned to remove
the mercury, the person performing the operation should be informed of mercury's hazardous properties.
Non-impervious clothing which becomes contaminated with mercury should be removed promptly and not reworn until the mercury is removed from the clothing.
Sanitation
Workers subject to skin contact with liquid mercury should wash with soap or mild
detergent and water any areas of the body which may have contacted mercury at the
end attach work day.
Skin that becomes contaminated with mercury should be promptly washed or showered with soap or mild detergent and water to remove any mercury.
Eating and smoking should not be permitted in areas where mercury is handled, processed, or stored.
Employees who handle mercury should wash their hands thoroughly with soap or mild detergent and water before eating, smoking, or using toilet facilities.
Common Operations and Controls
The accompanying table, part 1 and part 2, includes some common operations in which exposure to mercury may occur and control methods which may be effective in each case.
Emergency First Aid Procedures
In the event of an emergency, institute first aid procedures and send for first aid or
medical assistance.
Eye Exposure
If liquid mercury gets into the eyes, wash eyes immediately with large amounts of water, lifting the lower and upper lids occasionally. If irritation is present after
washing, get medical attention. Contact lenses should not be worn when working
with this chemical.
Skin Exposure
If liquid mercury gets on the skin, promptly wash the contaminated skin using soap or
mild detergent and water. If liquid mercury penetrates through the clothing, remove
the clothing promptly and wash the skin using soap or mild detergent and water. If
irritation persists after washing, get medical attention.
Breathing
If a person breathes in large amounts of mercury, move the exposed person to fresh
air at once. If breathing has stopped, perform artificial respiration. Keep the affected person warm and at rest. Get medical attention as soon as possible.
Swallowing
When large quantities of mercury have been swallowed or mercury has been swallowed repeatedly and the person is conscious, give the person large quantities of water immediately. After the water has been swallowed, try to get the person to vomit by having him touch the back of his throat with his finger. Do not make an unconscious person vomit. Get medical attention immediately.
Rescue
Move the affected person from the hazardous exposure. If the exposed person has
been overcome, notify someone else and put into effect the established emergency
rescue procedures. Do not become a casualty. Understand the facility's emergency
rescue procedures and know the locations of rescue equipment before the need
arises.
Spill Procedures
Persons not wearing protective equipment and clothing should be restricted from
areas of spills until cleanup has been completed.
If mercury is spilled, the following steps should be taken:
l. Ventilate area of spill.
2. Collect spilled material for reclamation using commercially available mercury
vapor depressants or specialized vacuum cleaners.
References
American Conference of Governmental Industrial Hygienists: "Mercury as Hg,"
Documentation of the Threshold Limit Values for Substances in Workroom Air (3rd
ed., 2nd printing), Cincinnati, 1974.
American Industrial Hygiene Association: "Mercury and Its Inorganic Compounds,"
Hygienic Guide Series, Detroit, Michigan, 1966.
American National Standard Acceptable Concentrations - Mercury: ANSI-Z37.8-1972, American National Standards Institute, Inc., New York, 1972.
Danziger, S. J., and Possick, P. A.: "Metallic Mercury Exposure in Scientific Glassware Manufacturing Plants," Journal of Occupational Medicine, 15:1, pp.
15-20,1973.
Deichmann, W. B., and Gerarde, H. W.: Toxicology of Drugs and Chemicals,
Academic Press, New York, 1969.
Gleason, M. N., Gosselin, R. E., Hodge, H. C., and Smith. R. P.: Clinical Toxicology of Commercial Products (3rd ed.), Williams and Wilkins, Baltimore, 1969.
Grant, W. M.: Toxicology of the Eye (2nd ed.), C. C. Thomas, Springfield, Illinois,
1974.
International Labour Office: Encyclopedia of Occupational Health and Safety,
McGraw-Hill, New York, 1971.
Kirk, R., and Othmer, D.: Encyclopedia of Chemical Technology (2nd ed.),
Interscience, New York, 1968.
Mercury Poisoning, Occupational Health Technical Information Service, California
State Department of Public Health, 1963.
National Institute for Occupational Safety and Health, U.S. Department of Health,
Education, and Welfare: Criteria for a Recommended Standard. . . Occupational
Exposure to Inorganic Mercury. HEW Publication No. HSM 73-11024, GPO No.
017-033-00022, U.S. Government Printing Office, Washington, D.C., 1973.
Patty, F. A. (ed.): Toxicology, Vol. II of Industrial Hygiene and Toxicology (2nd ed.
rev.), Interscience, New York, 1963.
Vostal, J. 3., and Clarkson, T. W.: "Mercury as an Environmental Hazard," Journal of
Occupational Medicine, 15:649-656, 1973.
"Working with Mercury in Industry," U.S. Department of Health. Education, and
Welfare Pamphlet, U.S. Government Printing Office, Washington, D.C., 1973.
Health effects of chronic mercury exposure by the University of California