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Potential Lead Hazards
JUNE 1987. VOL. 45. NO 6
AORN J O U R N A L
Potential Lead Hazards THEPRESENCE OF LEADIN AUTOCLAVEINDICATORS Arthur E. Davis, Jr, MD
T
oday, the use of autoclave tapes and strips is universally accepted in hospitals to indicate that instruments and other materials have been adequately sterilized. The tape is generally used to wrap and secure the pack for sterilization. Indicator strips, or small segments of tape, are placed inside the pack. The color change that occurs in autoclave indicator tapes and strips (usually white to black) depends on the conversion of lead carbonate and sulfur to lead sulfide. This conversion is produced by the heat, pressure, and moisture during the autoclave cycle. Three sources of potential lead contamination for operating room personnel associated with this process are from: hand contact with the tape, contact of strip to instruments, and actual vaporization of the lead or lead compounds during autoclaving. In this article, an overview of health hazards associated with exposure to lead is given. Two methods are presented that measure the first two of these sources of lead contamination. The resulting measurements are shown, and recornmendations for operating room procedures to prevent contact with lead are given.
inhaled, especially in large cities, because the air that we breathe contains large amounts of lead from exhaust fumes. This degree of lead absorption now often exceeds the normal elimination mechanisms of the body. Because of this vast source of lead contamination with the resultant heavy burden of body lead, we are living dangerously close to a physiological limit for total body lead content. The handling of autoclaving tape and strip indicators as well as the vaporization of lead during autoclaving are sources of potential lead contamination. We are now at the stage where any additional exposure that can be avoided should be avoided. Lead is absorbed through the gastrointestinal tract and the lungs. Lead poisoning primarily
Environmental Exposure
I
n a sense, we are all now lead poisoned. Before the industrial revolution, the total body burden of lead was about 2 mg. In industrialized societies, the whole body lead content is now about 200 mg. We ingest about 250 mg of lead a day in our food and water. Additional amounts are 1378
Arthur E. Davis, Jr, MD, is the medical director of the Department of Forensic Toxicology at Roche-Biomedical Reference Laboratories, Burlington, NC. He received hk medical degree from the University of Minnesota, Minneapolis.
JUNE 1987, VOL. 45, NO 6
AORN JOURNAL
Several papers have implicated lead poisoning from plumbing as a major factor in the decline of the Roman Empire. affects the brain, peripheral nervous system, gastrointestinal tract, kidneys, and the development of the red blood cells. Most other organ systems are also involved, and recently lead has been implicated in premature arteriosclerosis and cardiac hypertrophy.' The symptoms and findings are nonspecific, and may include crampy diffuse abdominal pain, anorexia, vomiting, constipation, headache, dizziness, lethargy, lack of coordination, irritability, memory lapses, somnolence, seizures, blindness, coma, and psychosis. The findings in kidney disease are entirely nonspecific and include glycosuria, proteinuria, hyperphosphaturia, hyperuricemia, and renal failure.2 The anemia can be microcytic, hypochromic or normocytic normochromic. Basophilic stippling is often seen.3 We know a great deal about heavy lead exposure that results in death or acute and chronic illness, but the subtle consequences of chronic lowlevel exposure are just beginning to be appreciated by the scientific community. Almost any exposure during early childhood may present risk of permanent injury to the nervous system even though no symptoms were detected at the time of exposure. Learning difficulties, drop in IQ, auditory and visual difficulties, and many behavioral problems are often reported. Recently, two papers showed that lead may be associated with the sudden infant death ~ y n d r o m e Lead . ~ is a neurotoxic agent that passes the blood-brain and placental barriers5 The developing nervous system is far more sensitive to lead. Also, infants and children absorb and retain much more lead than adults.
BC, first recognized acute lead poisoning and attributed it to white lead. Devonshire colic in 1724 was initially thought to be a highly infectious epidemic disease, but was later found to be caused by the high content of lead in cider stored in lead-contaminated crocks that were made in Devonshire. In 1863 it was noted that lead poisoning caused chronic nephritis in Serbia. About 25 years ago in Europe, a US ambassador became very sick and was brought home. It was finally determined that for two years, while he lived in an old palace in Italy, lead droppings from the decaying dining room ceiling had contaminated his food. In 1986, a researcher used atomic absorption analytic techniques to identify a 17th century lead poisoning epidemic evident in slave bones from Barbados.6 Several papers written by serious scholars have implicated lead poisoning from plumbing as a major factor in the decline of the Roman Empire. Additional sources of lead contamination are almost too numerous to mention. These include mining, smelting, manufacturing, crumbling paint from old buildings, sanding or burning old painted wood, glazing putty, glazing on pottery and dishes, soldering, pots and pans, lead toys and jewelry, moonshine liquor, and old batteries. There is considerable lead in printing ink, and poisoning has occurred from burning magazines and newspapers in stoves and fireplaces.' Unusual cases such as lead poisoning in a family using leaded cocktail glasses are becoming more common.6
Historical Diagnoses
perating room personnel can come in contact with lead by touching the tape and strip indicators used in autoclaving surgical instruments. Also, the contact of strip to instruments and the vaporizing of lead or its
H
istorically, both acute and chronic lead poisoning have been very difficult to diagnose. Nikander, in the second century
1380
Measurement Methods and Results
0
JUNE 1987, VOL. 45, NO 6
AORN J O U R N A L
Table 1
Atomic Absorption Test Micrograms of Lead Per Strip/Tape
Brand
mg/lead
A
7.440
B
3,820
C
2,430
D
10.000
compounds during autoclaving are additional sources of exposure to lead. For this paper, two measures were developed that evaluated the lead amounts present in the tape itself and those present when human hands touch the tape or strips. First, an atomic absorption test was used to measure the lead content of four major brands of strips and one brand of tape. Table 1 shows the micrograms of lead contained in the strips and tape. Second, a quantitative analysis was designed to reasonably approximate the normal daily activities of operating room personnel in the use of indicator strips, both before and after autoclaving. Called a rub test, the second set of measurements involved chamois skins cut into 1.3 mm squares to approximate the fingertip contact area. The tape and strips were gently rubbed with the squares of chamois for three, five, and 18 seconds respectively. The squares were then transferred to glass containers of concentrated nitric acid (70%) and heated for two hours at 80 "C (176 O F ) . The digestion of the chamois skin was complete after 20 minutes, but the process was continued for the balance of two hours to ensure the solubilization of the lead. Appropriate positive and negative controls were run. Multiple standards were used for the positive controls. Lead tests were performed on all chamois skins
before use. The resultant solution was brought to a standard known volume of 100 mL with triple-distilled slightly acidic water. A lead assay was then run in duplicate using standard methodology and an atomic absorption instrument. The findings of the assay are shown in Table 2. It is clear that in 11 of 15 separate tests, the amount of lead removed in rubbing the tape and strips was higher after autoclaving than it was before autoclaving. The increase was especially dramatic when rubbing occurred for five and 18 seconds. For example, 50 micrograms of lead were obtained from the strip Brand C when it was rubbed for 18 seconds before autoclaving. But after autoclaving, the same brand produced 441 micrograms of lead when rubbed for the same amount of time. Interestingly, however, the tape Brand E showed only small increases in lead amounts after autoclaving. Also, Brands B and D decreased slightly in lead amounts for the three-second rub test after autoclaving, and Brand D showed fewer micrograms of lead present after autoclaving in the five-second test. To gain some understanding of what these lead levels mean, it may be useful to note that the Environmental Protection Agency has set the maximum safe level of lead in drinking water not to exceed 25 parts per million (25 micrograms). 1381
JUNE 1987, VOL. 45, NO 6
AORN J O U R N A L
Table 2
Quantitative Analysis (Rub Test)” Pre-Autoclave
Post-Autoclave
3 see
5 see
18 sec
3 see
5 see
18 see
A
10
52
137
24
166
623
B
18
61
218
16
86
300
C
< 10
24
50
42
200
44 1
D
18
72
157
13
54
229
< 10
< 10
10
< 10
13
17
Brand
E (tape)
* Amount of lead removed in each increment of rubbing in micrograms. One microgram ( p g ) is one millionth of a gram. Certainly the comparison of lead ingested in the body with lead exposure through skin contact is not a strict comparison. It may nevertheless indicate that a minute amount of ingested lead presents a hazard. More studies to assess the dangers of lead exposure to the skin are advisable. We are just now beginning to appreciate the toxicity of accidental lead exposure.
Conclusions and Recommendations
I
n the United States approximately 26,000 pounds of lead are used every year in autoclave indicator strips and tapes. The studies in this report provide initial evidence of hazardous lead contamination in the hospital environment. Further clinical epidemiological studies should be undertaken. Until these studies have been completed, precautions such as wearing gloves during any strip or tape contact should be exercised, and at-risk personnel should be monitored with appropriate laboratory tests. 0 Notes 1. J M Kissane, Anderson’s Pathologv, seventh ed (St Louis: C V Mosby Co, 1985) 201. 2. R P Wedeen et al, “Occupational lead nephropathy,” American Journal of Medicine 59 (November 1382
1975) 630-641. 3. R P Wedeen, K D Malik, V Bautman, “Detection and treatment of occupational lead nephropathy,” Archives of Internal Medicine I39 (January 1979) 5357. 4. M M Erickson et al, “Tissue mineral levels in victims of sudden infant death syndrome I: Toxic metals-lead and cadmium,” Pediatric Research 17 (October 1983) 779-784. 5. T Lyngbye et al, “Lead as a cause of SIDS,” New England Journal of Medicine 313 (October 10, 1985) 954-955. 6. A Aufderheide, “17th Century lead poisoning epidemic diagnosed,” Medical Bulletin. University of Minnesota (Spring/Summer 1986) 6. 7. D B Louria, “Trace metal poisoning 518.2 lead,” Internal Medicine 16th ed (Philadephia:W B Saunders Co, 1982) xxii2218-2222. 8. L Dickinson et al, “Lead poisoning in a family due to cocktail glasses,” American Journal of Medicine 52 (March 1972) 391-394.
AORN J O U R N A L
Potential Lead Hazards THEPRESENCE OF LEADIN AUTOCLAVEINDICATORS Arthur E. Davis, Jr, MD
T
oday, the use of autoclave tapes and strips is universally accepted in hospitals to indicate that instruments and other materials have been adequately sterilized. The tape is generally used to wrap and secure the pack for sterilization. Indicator strips, or small segments of tape, are placed inside the pack. The color change that occurs in autoclave indicator tapes and strips (usually white to black) depends on the conversion of lead carbonate and sulfur to lead sulfide. This conversion is produced by the heat, pressure, and moisture during the autoclave cycle. Three sources of potential lead contamination for operating room personnel associated with this process are from: hand contact with the tape, contact of strip to instruments, and actual vaporization of the lead or lead compounds during autoclaving. In this article, an overview of health hazards associated with exposure to lead is given. Two methods are presented that measure the first two of these sources of lead contamination. The resulting measurements are shown, and recornmendations for operating room procedures to prevent contact with lead are given.
inhaled, especially in large cities, because the air that we breathe contains large amounts of lead from exhaust fumes. This degree of lead absorption now often exceeds the normal elimination mechanisms of the body. Because of this vast source of lead contamination with the resultant heavy burden of body lead, we are living dangerously close to a physiological limit for total body lead content. The handling of autoclaving tape and strip indicators as well as the vaporization of lead during autoclaving are sources of potential lead contamination. We are now at the stage where any additional exposure that can be avoided should be avoided. Lead is absorbed through the gastrointestinal tract and the lungs. Lead poisoning primarily
Environmental Exposure
I
n a sense, we are all now lead poisoned. Before the industrial revolution, the total body burden of lead was about 2 mg. In industrialized societies, the whole body lead content is now about 200 mg. We ingest about 250 mg of lead a day in our food and water. Additional amounts are 1378
Arthur E. Davis, Jr, MD, is the medical director of the Department of Forensic Toxicology at Roche-Biomedical Reference Laboratories, Burlington, NC. He received hk medical degree from the University of Minnesota, Minneapolis.
JUNE 1987, VOL. 45, NO 6
AORN JOURNAL
Several papers have implicated lead poisoning from plumbing as a major factor in the decline of the Roman Empire. affects the brain, peripheral nervous system, gastrointestinal tract, kidneys, and the development of the red blood cells. Most other organ systems are also involved, and recently lead has been implicated in premature arteriosclerosis and cardiac hypertrophy.' The symptoms and findings are nonspecific, and may include crampy diffuse abdominal pain, anorexia, vomiting, constipation, headache, dizziness, lethargy, lack of coordination, irritability, memory lapses, somnolence, seizures, blindness, coma, and psychosis. The findings in kidney disease are entirely nonspecific and include glycosuria, proteinuria, hyperphosphaturia, hyperuricemia, and renal failure.2 The anemia can be microcytic, hypochromic or normocytic normochromic. Basophilic stippling is often seen.3 We know a great deal about heavy lead exposure that results in death or acute and chronic illness, but the subtle consequences of chronic lowlevel exposure are just beginning to be appreciated by the scientific community. Almost any exposure during early childhood may present risk of permanent injury to the nervous system even though no symptoms were detected at the time of exposure. Learning difficulties, drop in IQ, auditory and visual difficulties, and many behavioral problems are often reported. Recently, two papers showed that lead may be associated with the sudden infant death ~ y n d r o m e Lead . ~ is a neurotoxic agent that passes the blood-brain and placental barriers5 The developing nervous system is far more sensitive to lead. Also, infants and children absorb and retain much more lead than adults.
BC, first recognized acute lead poisoning and attributed it to white lead. Devonshire colic in 1724 was initially thought to be a highly infectious epidemic disease, but was later found to be caused by the high content of lead in cider stored in lead-contaminated crocks that were made in Devonshire. In 1863 it was noted that lead poisoning caused chronic nephritis in Serbia. About 25 years ago in Europe, a US ambassador became very sick and was brought home. It was finally determined that for two years, while he lived in an old palace in Italy, lead droppings from the decaying dining room ceiling had contaminated his food. In 1986, a researcher used atomic absorption analytic techniques to identify a 17th century lead poisoning epidemic evident in slave bones from Barbados.6 Several papers written by serious scholars have implicated lead poisoning from plumbing as a major factor in the decline of the Roman Empire. Additional sources of lead contamination are almost too numerous to mention. These include mining, smelting, manufacturing, crumbling paint from old buildings, sanding or burning old painted wood, glazing putty, glazing on pottery and dishes, soldering, pots and pans, lead toys and jewelry, moonshine liquor, and old batteries. There is considerable lead in printing ink, and poisoning has occurred from burning magazines and newspapers in stoves and fireplaces.' Unusual cases such as lead poisoning in a family using leaded cocktail glasses are becoming more common.6
Historical Diagnoses
perating room personnel can come in contact with lead by touching the tape and strip indicators used in autoclaving surgical instruments. Also, the contact of strip to instruments and the vaporizing of lead or its
H
istorically, both acute and chronic lead poisoning have been very difficult to diagnose. Nikander, in the second century
1380
Measurement Methods and Results
0
JUNE 1987, VOL. 45, NO 6
AORN J O U R N A L
Table 1
Atomic Absorption Test Micrograms of Lead Per Strip/Tape
Brand
mg/lead
A
7.440
B
3,820
C
2,430
D
10.000
compounds during autoclaving are additional sources of exposure to lead. For this paper, two measures were developed that evaluated the lead amounts present in the tape itself and those present when human hands touch the tape or strips. First, an atomic absorption test was used to measure the lead content of four major brands of strips and one brand of tape. Table 1 shows the micrograms of lead contained in the strips and tape. Second, a quantitative analysis was designed to reasonably approximate the normal daily activities of operating room personnel in the use of indicator strips, both before and after autoclaving. Called a rub test, the second set of measurements involved chamois skins cut into 1.3 mm squares to approximate the fingertip contact area. The tape and strips were gently rubbed with the squares of chamois for three, five, and 18 seconds respectively. The squares were then transferred to glass containers of concentrated nitric acid (70%) and heated for two hours at 80 "C (176 O F ) . The digestion of the chamois skin was complete after 20 minutes, but the process was continued for the balance of two hours to ensure the solubilization of the lead. Appropriate positive and negative controls were run. Multiple standards were used for the positive controls. Lead tests were performed on all chamois skins
before use. The resultant solution was brought to a standard known volume of 100 mL with triple-distilled slightly acidic water. A lead assay was then run in duplicate using standard methodology and an atomic absorption instrument. The findings of the assay are shown in Table 2. It is clear that in 11 of 15 separate tests, the amount of lead removed in rubbing the tape and strips was higher after autoclaving than it was before autoclaving. The increase was especially dramatic when rubbing occurred for five and 18 seconds. For example, 50 micrograms of lead were obtained from the strip Brand C when it was rubbed for 18 seconds before autoclaving. But after autoclaving, the same brand produced 441 micrograms of lead when rubbed for the same amount of time. Interestingly, however, the tape Brand E showed only small increases in lead amounts after autoclaving. Also, Brands B and D decreased slightly in lead amounts for the three-second rub test after autoclaving, and Brand D showed fewer micrograms of lead present after autoclaving in the five-second test. To gain some understanding of what these lead levels mean, it may be useful to note that the Environmental Protection Agency has set the maximum safe level of lead in drinking water not to exceed 25 parts per million (25 micrograms). 1381
JUNE 1987, VOL. 45, NO 6
AORN J O U R N A L
Table 2
Quantitative Analysis (Rub Test)” Pre-Autoclave
Post-Autoclave
3 see
5 see
18 sec
3 see
5 see
18 see
A
10
52
137
24
166
623
B
18
61
218
16
86
300
C
< 10
24
50
42
200
44 1
D
18
72
157
13
54
229
< 10
< 10
10
< 10
13
17
Brand
E (tape)
* Amount of lead removed in each increment of rubbing in micrograms. One microgram ( p g ) is one millionth of a gram. Certainly the comparison of lead ingested in the body with lead exposure through skin contact is not a strict comparison. It may nevertheless indicate that a minute amount of ingested lead presents a hazard. More studies to assess the dangers of lead exposure to the skin are advisable. We are just now beginning to appreciate the toxicity of accidental lead exposure.
Conclusions and Recommendations
I
n the United States approximately 26,000 pounds of lead are used every year in autoclave indicator strips and tapes. The studies in this report provide initial evidence of hazardous lead contamination in the hospital environment. Further clinical epidemiological studies should be undertaken. Until these studies have been completed, precautions such as wearing gloves during any strip or tape contact should be exercised, and at-risk personnel should be monitored with appropriate laboratory tests. 0 Notes 1. J M Kissane, Anderson’s Pathologv, seventh ed (St Louis: C V Mosby Co, 1985) 201. 2. R P Wedeen et al, “Occupational lead nephropathy,” American Journal of Medicine 59 (November 1382
1975) 630-641. 3. R P Wedeen, K D Malik, V Bautman, “Detection and treatment of occupational lead nephropathy,” Archives of Internal Medicine I39 (January 1979) 5357. 4. M M Erickson et al, “Tissue mineral levels in victims of sudden infant death syndrome I: Toxic metals-lead and cadmium,” Pediatric Research 17 (October 1983) 779-784. 5. T Lyngbye et al, “Lead as a cause of SIDS,” New England Journal of Medicine 313 (October 10, 1985) 954-955. 6. A Aufderheide, “17th Century lead poisoning epidemic diagnosed,” Medical Bulletin. University of Minnesota (Spring/Summer 1986) 6. 7. D B Louria, “Trace metal poisoning 518.2 lead,” Internal Medicine 16th ed (Philadephia:W B Saunders Co, 1982) xxii2218-2222. 8. L Dickinson et al, “Lead poisoning in a family due to cocktail glasses,” American Journal of Medicine 52 (March 1972) 391-394.