Dentists, dental nurses, and brain tumours

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Dentists, dental nurses, and brain tumours

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We investigated the risk of intracranial tumours in several occupational groups in a research programme.

In this report we present the risks of glioblastoma among dentists and dental nurses.

Subjects, methods,

 

 

Cohorts of dentists 

 

 

the years 1961-79.

There were 3454 male dentists, 1125 female dentists, and 4662 female dental nurses.

The

 

 

(ICD 193-0)  

in the cohorts, 18 were glioblastomas (astrocytomna III-IV according to Kernohan and Sayre4), four gliomas (astrocytoma I-II), and six meningiomas.

The 

 

 

calculated from the cumulative incidences for all employed people and the numbers of dentists and dental nurses. Stratification was by age (five year age groups), sex, and county. The cumulative incidences were calculated  as the proportion of the census population that was

-recorded in the cancer registry.The analysis was based on the standardised morbidity ratio-that is, the ratio of the observed number of cases to the expected number-with 95% confidence limits.5 For comparison standardised morbidity ratios for physicians and nurses were also calculated.for meningioma the standardised morbidity ratio was 1-3. For all tumours combined the standardised morbidity ratio was 1-0 or 1 1 for all the different groups. The standardised morbidity ratio for glioblastoma among physicians and nurses was estimated as 1-3 and 1-2, respectively, with unity well within the confidence intervals.

Comment

Although the 

 

 

The-basis for the diagnosis was either biopsy or necropsy 

 

 

We did

not take into account deaths

 

 

from competing causes, but although this

might

possibly

 

 

differ between people in the dental profession and the

general

population

 

 

it is unlikely to do so only in respect of glioblastoma.

Random

fluctuations

 

 

might explain the observed excess risk, but against this must

be

set the

 

 

consistency of the results, and, in particular, the similarity

of the

standard mortality ratio's for dentists and dental nurses and

 

 

for

male and

female

 

 

dentists.

In conclusion, we think it

 

 

unlikely that the sources of error

mentioned

above or factors known to be related to

 

 

glioblastoma explain

the observed

excess

 

 

risk. Most probably the origin is some occupational factor

common

to

 

 

dentists and dental nurses-for example, amalgam, chloroform,

or

radiography.

1

 

 

Zulch KJ, Mennel HD. New aspects of brain tumor research. I

Neurol 1977;214.241-50.

2

 

 

Schoenberg B. Nervous system. In: Schottenfeld IJ, Fraumeni JF Jr, eds. Cancer epidemiology

and

prevention. Philadelphia, Pa: W R Saunders,

 

 

1982:%8-83.

3

 

 

Olin R, Ahlbom A. The cancer mortality among

Swedish chemists graduating during three

decades. A

 

 

comparison with the general population and with a cohort of

architects. Environ Res

1980;22:154-61.

4

 

 

Kemohan JW, Sayre GP. Tumors of the central nervous system.

Atlas of tumor pathology.

Washington, DC: Arned

 

 

Forces Institute of Pathology,

1952.

5 Rothman

 

 

KJ, Boice JD Jr. Epideniological anatyses twith a programmabk calculator. Boston,

Mass:

Epidemiology Resources, 1982:30-1.

(Accepted

 

 

13

December 1985)

Department of Epidemiology, National Institute ofEnvironmental

 

 

Medicine,

Stockholm, Sweden

ANDERS AHLBOM, PHD, professor

STAFFAN NORELL,mD, associate

 

 

professor

YVALL RODVALL, BA, research assistant

Department

 

 

of Hygiene, The Karolinska

Institute, Stockholm, Sweden

MAGNUS NYLANDER, DD, research assistant

Correspondence

 

 

to:

Dr Ahlbom.

Observed and expected numbers of

 

 

tumours and standardised morbidity ratios among dentists and dental

nurses*

Observed Expected

 

 

Standard

95%

No of No of morbidity Confidence

Diagnosis and category tumours tumours ratio limit

Glioblastoma (astrocytoma III-IV) 18 8-47 2-1 13-34

Dentists, male 9 4 56 2-0

 

 

0 9-

3-7

Dentists, female 3 1-22 2-5 0 5-

 

 

7-2

Dental nurses, female 6 2-69 2-2 0-8-

 

 

4 9

Physicians 11 8-48 1-3 0-6-2-3

Nurses, female 23 19-36

 

 

1-2

0-8-1-8

Glioma (astrocytoma I-II) 4 2-20 1-8

 

 

0

5-4 7

Dentists, male 2 0 99 2-0

 

 

0-2-

7-3

Dentists, female 0-24 00 00-154

Dentalnurses,female 2 097 2-1 0-2-

 

 

7-4

Meningioma 6 4-59 1-3 0-5-2-8

Dentists,male

 

 

4 1-56 26 0

7- 66

Dentists,

 

 

female 1 1-00 1-0 0-0- 5-6

Dental nurses, female 1 2-03 0 5 0 0- 2-7

All tumours 5% 572-31 1.0 10-1

 

 

1

Dentists, male 288 276-20 1-0 0 9- 1 2

Dentists, female 97 98-78 10

 

 

0-8- 1-2

Dentalnurses,female 211 197-33 1.1 09- 1-2

*Gioma

 

 

and meningoma controlled only for sex and agei other diagnoses controlled

for sex, age, and county.

findings. 100% census gave the number of people whose present occupation was as a dentist or dental nurse, it did not provide information on the duration or level of exposure to products used in dental work. There might also have been errors in the reporting or coding of occupations in the census. Thus we may have included in our study people with little or no exposure to products used in dental work which could lead to underestimation of the increased risk. For 17 of the 18 cases qf glioblastoma we were able to locate and review the medical records and thus determined that all these patients had indeed been assigned the diagnosis of glioblastoma.

The table shows that among dentists and dental nurses glioblastoma was about twice as common as expected. For glioma the standardised morbidity ratio for the entire study population was 1-8, although with a wide confidence interval, while

observed numbers of cases of cancer were compared with the corresponding expected numbers,  histopathological classification showed that of the brain tumours and dental nurses aged 20-64 were identified from the Swedish census of 1960, and people within these cohorts who had cancer were identified from a record linkage to the cancer register for and results

important in the origin of brain tumours.

 

We investigated the risk of intracranial tumours in several occupational groups in a research programme.

In this report we present the risks of glioblastoma among dentists and dental nurses.

Subjects, methods,

 

 

Cohorts of dentists 

 

 

the years 1961-79.

There were 3454 male dentists, 1125 female dentists, and 4662 female dental nurses.

The

 

 

(ICD 193-0)  

in the cohorts, 18 were glioblastomas (astrocytomna III-IV according to Kernohan and Sayre4), four gliomas (astrocytoma I-II), and six meningiomas.

The 

 

 

calculated from the cumulative incidences for all employed people and the numbers of dentists and dental nurses. Stratification was by age (five year age groups), sex, and county. The cumulative incidences were calculated  as the proportion of the census population that was

-recorded in the cancer registry.The analysis was based on the standardised morbidity ratio-that is, the ratio of the observed number of cases to the expected number-with 95% confidence limits.5 For comparison standardised morbidity ratios for physicians and nurses were also calculated.for meningioma the standardised morbidity ratio was 1-3. For all tumours combined the standardised morbidity ratio was 1-0 or 1 1 for all the different groups. The standardised morbidity ratio for glioblastoma among physicians and nurses was estimated as 1-3 and 1-2, respectively, with unity well within the confidence intervals.

Comment

Although the 

 

 

The-basis for the diagnosis was either biopsy or necropsy 

 

 

We did

not take into account deaths

 

 

from competing causes, but although this

might

possibly

 

 

differ between people in the dental profession and the

general

population

 

 

it is unlikely to do so only in respect of glioblastoma.

Random

fluctuations

 

 

might explain the observed excess risk, but against this must

be

set the

 

 

consistency of the results, and, in particular, the similarity

of the

standard mortality ratio's for dentists and dental nurses and

 

 

for

male and

female

 

 

dentists.

In conclusion, we think it

 

 

unlikely that the sources of error

mentioned

above or factors known to be related to

 

 

glioblastoma explain

the observed

excess

 

 

risk. Most probably the origin is some occupational factor

common

to

 

 

dentists and dental nurses-for example, amalgam, chloroform,

or

radiography.

1

 

 

Zulch KJ, Mennel HD. New aspects of brain tumor research. I

Neurol 1977;214.241-50.

2

 

 

Schoenberg B. Nervous system. In: Schottenfeld IJ, Fraumeni JF Jr, eds. Cancer epidemiology

and

prevention. Philadelphia, Pa: W R Saunders,

 

 

1982:%8-83.

3

 

 

Olin R, Ahlbom A. The cancer mortality among

Swedish chemists graduating during three

decades. A

 

 

comparison with the general population and with a cohort of

architects. Environ Res

1980;22:154-61.

4

 

 

Kemohan JW, Sayre GP. Tumors of the central nervous system.

Atlas of tumor pathology.

Washington, DC: Arned

 

 

Forces Institute of Pathology,

1952.

5 Rothman

 

 

KJ, Boice JD Jr. Epideniological anatyses twith a programmabk calculator. Boston,

Mass:

Epidemiology Resources, 1982:30-1.

(Accepted

 

 

13

December 1985)

Department of Epidemiology, National Institute ofEnvironmental

 

 

Medicine,

Stockholm, Sweden

ANDERS AHLBOM, PHD, professor

STAFFAN NORELL,mD, associate

 

 

professor

YVALL RODVALL, BA, research assistant

Department

 

 

of Hygiene, The Karolinska

Institute, Stockholm, Sweden

MAGNUS NYLANDER, DD, research assistant

Correspondence

 

 

to:

Dr Ahlbom.

Observed and expected numbers of

 

 

tumours and standardised morbidity ratios among dentists and dental

nurses*

Observed Expected

 

 

Standard

95%

No of No of morbidity Confidence

Diagnosis and category tumours tumours ratio limit

Glioblastoma (astrocytoma III-IV) 18 8-47 2-1 13-34

Dentists, male 9 4 56 2-0

 

 

0 9-

3-7

Dentists, female 3 1-22 2-5 0 5-

 

 

7-2

Dental nurses, female 6 2-69 2-2 0-8-

 

 

4 9

Physicians 11 8-48 1-3 0-6-2-3

Nurses, female 23 19-36

 

 

1-2

0-8-1-8

Glioma (astrocytoma I-II) 4 2-20 1-8

 

 

0

5-4 7

Dentists, male 2 0 99 2-0

 

 

0-2-

7-3

Dentists, female 0-24 00 00-154

Dentalnurses,female 2 097 2-1 0-2-

 

 

7-4

Meningioma 6 4-59 1-3 0-5-2-8

Dentists,male

 

 

4 1-56 26 0

7- 66

Dentists,

 

 

female 1 1-00 1-0 0-0- 5-6

Dental nurses, female 1 2-03 0 5 0 0- 2-7

All tumours 5% 572-31 1.0 10-1

 

 

1

Dentists, male 288 276-20 1-0 0 9- 1 2

Dentists, female 97 98-78 10

 

 

0-8- 1-2

Dentalnurses,female 211 197-33 1.1 09- 1-2

*Gioma

 

 

and meningoma controlled only for sex and agei other diagnoses controlled

for sex, age, and county.

findings. 100% census gave the number of people whose present occupation was as a dentist or dental nurse, it did not provide information on the duration or level of exposure to products used in dental work. There might also have been errors in the reporting or coding of occupations in the census. Thus we may have included in our study people with little or no exposure to products used in dental work which could lead to underestimation of the increased risk. For 17 of the 18 cases qf glioblastoma we were able to locate and review the medical records and thus determined that all these patients had indeed been assigned the diagnosis of glioblastoma.

The table shows that among dentists and dental nurses glioblastoma was about twice as common as expected. For glioma the standardised morbidity ratio for the entire study population was 1-8, although with a wide confidence interval, while

observed numbers of cases of cancer were compared with the corresponding expected numbers,  histopathological classification showed that of the brain tumours and dental nurses aged 20-64 were identified from the Swedish census of 1960, and people within these cohorts who had cancer were identified from a record linkage to the cancer register for and results

important in the origin of brain tumours. important in the origin of brain tumours. some evidence to suggest that exogenous factors might be

 

We investigated the risk of intracranial tumours in several occupational groups in a research programme.

In this report we present the risks of glioblastoma among dentists and dental nurses.

Subjects, methods,

 

 

Cohorts of dentists 

 

 

the years 1961-79.

There were 3454 male dentists, 1125 female dentists, and 4662 female dental nurses.

The

 

 

(ICD 193-0)  

in the cohorts, 18 were glioblastomas (astrocytomna III-IV according to Kernohan and Sayre4), four gliomas (astrocytoma I-II), and six meningiomas.

The 

 

 

calculated from the cumulative incidences for all employed people and the numbers of dentists and dental nurses. Stratification was by age (five year age groups), sex, and county. The cumulative incidences were calculated  as the proportion of the census population that was

-recorded in the cancer registry.The analysis was based on the standardised morbidity ratio-that is, the ratio of the observed number of cases to the expected number-with 95% confidence limits.5 For comparison standardised morbidity ratios for physicians and nurses were also calculated.for meningioma the standardised morbidity ratio was 1-3. For all tumours combined the standardised morbidity ratio was 1-0 or 1 1 for all the different groups. The standardised morbidity ratio for glioblastoma among physicians and nurses was estimated as 1-3 and 1-2, respectively, with unity well within the confidence intervals.

Comment

Although the 

 

 

The-basis for the diagnosis was either biopsy or necropsy 

 

 

We did

not take into account deaths

 

 

from competing causes, but although this

might

possibly

 

 

differ between people in the dental profession and the

general

population

 

 

it is unlikely to do so only in respect of glioblastoma.

Random

fluctuations

 

 

might explain the observed excess risk, but against this must

be

set the

 

 

consistency of the results, and, in particular, the similarity

of the

standard mortality ratio's for dentists and dental nurses and

 

 

for

male and

female

 

 

dentists.

In conclusion, we think it

 

 

unlikely that the sources of error

mentioned

above or factors known to be related to

 

 

glioblastoma explain

the observed

excess

 

 

risk. Most probably the origin is some occupational factor

common

to

 

 

dentists and dental nurses-for example, amalgam, chloroform,

or

radiography.

1

 

 

Zulch KJ, Mennel HD. New aspects of brain tumor research. I

Neurol 1977;214.241-50.

2

 

 

Schoenberg B. Nervous system. In: Schottenfeld IJ, Fraumeni JF Jr, eds. Cancer epidemiology

and

prevention. Philadelphia, Pa: W R Saunders,

 

 

1982:%8-83.

3

 

 

Olin R, Ahlbom A. The cancer mortality among

Swedish chemists graduating during three

decades. A

 

 

comparison with the general population and with a cohort of

architects. Environ Res

1980;22:154-61.

4

 

 

Kemohan JW, Sayre GP. Tumors of the central nervous system.

Atlas of tumor pathology.

Washington, DC: Arned

 

 

Forces Institute of Pathology,

1952.

5 Rothman

 

 

KJ, Boice JD Jr. Epideniological anatyses twith a programmabk calculator. Boston,

Mass:

Epidemiology Resources, 1982:30-1.

(Accepted

 

 

13

December 1985)

Department of Epidemiology, National Institute ofEnvironmental

 

 

Medicine,

Stockholm, Sweden

ANDERS AHLBOM, PHD, professor

STAFFAN NORELL,mD, associate

 

 

professor

YVALL RODVALL, BA, research assistant

Department

 

 

of Hygiene, The Karolinska

Institute, Stockholm, Sweden

MAGNUS NYLANDER, DD, research assistant

Correspondence

 

 

to:

Dr Ahlbom.

Observed and expected numbers of

 

 

tumours and standardised morbidity ratios among dentists and dental

nurses*

Observed Expected

 

 

Standard

95%

No of No of morbidity Confidence

Diagnosis and category tumours tumours ratio limit

Glioblastoma (astrocytoma III-IV) 18 8-47 2-1 13-34

Dentists, male 9 4 56 2-0

 

 

0 9-

3-7

Dentists, female 3 1-22 2-5 0 5-

 

 

7-2

Dental nurses, female 6 2-69 2-2 0-8-

 

 

4 9

Physicians 11 8-48 1-3 0-6-2-3

Nurses, female 23 19-36

 

 

1-2

0-8-1-8

Glioma (astrocytoma I-II) 4 2-20 1-8

 

 

0

5-4 7

Dentists, male 2 0 99 2-0

 

 

0-2-

7-3

Dentists, female 0-24 00 00-154

Dentalnurses,female 2 097 2-1 0-2-

 

 

7-4

Meningioma 6 4-59 1-3 0-5-2-8

Dentists,male

 

 

4 1-56 26 0

7- 66

Dentists,

 

 

female 1 1-00 1-0 0-0- 5-6

Dental nurses, female 1 2-03 0 5 0 0- 2-7

All tumours 5% 572-31 1.0 10-1

 

 

1

Dentists, male 288 276-20 1-0 0 9- 1 2

Dentists, female 97 98-78 10

 

 

0-8- 1-2

Dentalnurses,female 211 197-33 1.1 09- 1-2

*Gioma

 

 

and meningoma controlled only for sex and agei other diagnoses controlled

for sex, age, and county.

findings. 100% census gave the number of people whose present occupation was as a dentist or dental nurse, it did not provide information on the duration or level of exposure to products used in dental work. There might also have been errors in the reporting or coding of occupations in the census. Thus we may have included in our study people with little or no exposure to products used in dental work which could lead to underestimation of the increased risk. For 17 of the 18 cases qf glioblastoma we were able to locate and review the medical records and thus determined that all these patients had indeed been assigned the diagnosis of glioblastoma.

The table shows that among dentists and dental nurses glioblastoma was about twice as common as expected. For glioma the standardised morbidity ratio for the entire study population was 1-8, although with a wide confidence interval, while

observed numbers of cases of cancer were compared with the corresponding expected numbers,  histopathological classification showed that of the brain tumours and dental nurses aged 20-64 were identified from the Swedish census of 1960, and people within these cohorts who had cancer were identified from a record linkage to the cancer register for and results