DEGREE OF ASBESTOS EXPOSURE IN PERITONEAL AND PLEURAL MESOTHELIOMA PATIENTS

Dr Boloor Sudhir Rao, Professor Doug Henderson, Asst Prof. Sonja Klebe, Dr Jeffrey J Bowden

IntroductionPeritoneal Mesothelioma patients were thought to be associatedpreferentially with longer and heavier exposure to asbestos[1-3]incomparison to patients with pleural mesothelioma.

AimThe aim of our study was to assess the degree of asbestos exposurein a cohort of 110 age and gender matched, histologically confirmed cases of peritoneal and pleural mesothelioma patients.

MethodDetailed employment history and exposure data were provided for most patients to lawyers as part of medico-legal cases. Based on this, exposure was categorized by type and dose. Type of exposurewas classified as Domestic (including childhood exposure); By-stander and Occupational. Dose of exposure was estimated to be low-dose or substantial based on extrapolation from the rating scale designed by Newhouse[4].

Grade 1 (very low)Staff and officeGrounds, gardens, and gatemanCanteenLaboratoryStoresChildhoodMfc. Rubber joining BCMfc. Asbestos building boards ACMfc. Brake linings C

Grade 2 (low)Clothing storesWorks and buildingsCleanersMfc. Insulating material CBy-standerDomestic

Grade 3 (moderate)Metal shopEngineersElectricianDespatch and PackingLaundry DomesticHome-renovationHandyman

Grade 4 (moderate-severe)Laggers ABCMates ABCLabourers ABC

Grade 5 (Severe)No periodic medical examinationYarn store BARP lapping BBulk insulation material ABC

Grade 6 (Severe)Periodic medical examinationDisintegrating ABCCarding ABSpinning CDoubling BMattress making AB 1936 onwardsCrude Store ABDust and waste ABC

1 Asbestos content of product less than 20%A=Amosite; B= Crocidolite; C= Chrysotile

Newhouse Rating Scale for Asbestos Exposure (original and modified)

Results- Estimated Asbestos Exposure

21

761

5

1

14

Peritoneal Mesothelioma n=55Occupational

Domestic

Home renovation

Handyman

By-stander

Childhood

Unknown

17

11

122

31

Pleural Mesothelioma n=55

Occupational

Domestic

Home Renovation

Handyman

By-stander

Childhood

Unknown

Type of Exposure

1 3 5 7 9 11 13 15 17 19 21 230

5

10

15

20

25

30

35

40

45

Duration of Exposure(Years)

Duration of Ex-posure(Years)

1 3 5 7 9 11 13 15 17 19 21 23 250

5

10

15

20

25

30

35

40

Duration of Exposure (Years)

Duration of Exposure (Years)

Peritoneal Mesothelioma Pleural Mesothelioma0.00%

5.00%

10.00%

15.00%

20.00%

25.00%

30.00%

35.00%

40.00%

45.00%

32.72%

16.36%

41.81%

25.45%

LowSubstantial

Pleural Mesothelioma Peritoneal Mesothelioma

Duration of Exposure

Dose of Exposure

ConclusionThis study indicated that relatively low dose exposure can result inPeritoneal Mesothelioma and supports the current understanding that thereIs no threshold of exposure below which peritoneal mesothelioma will not occur, similar to Pleural Mesotheliomas

Bibliography1. Cocco P, Dosemeci M: Peritoneal cancer and occupational exposure to asbestos: results from the application of a job-exposure matrix. Am J Ind Med1999, 35:9–14.2. Yates DH, Corrin B, Stidolph PN, Browne K: Malignant mesothelioma in south east England: clinicopathologicalexperience of 272 cases [published erratumappears in Thorax 1997, 52:1018]. Thorax 1997,52:507–12.3. Browne K, Smither WJ: Asbestos-related mesothelioma:factors discriminating between pleural andperitoneal sites. Br J Ind Med 1983, 40:145–1524. Newhousc ML . A study of the mortalitv of workers in an asbestosfactory . . Br J Ind Med 1969 :56 :294-301 .

DiscussionThe use of a modified Newhouse Rating Scale for assessing asbestosexposure is no doubt an over simplification of a controversial problem. But the aim here was to apply the same assessment scale to both the pleural mesothelioma cohort and the peritoneal mesothelioma cohort. This clearly shows that exposure to asbestos was similar in both cohorts. It also clearly showed that 32% of patients with peritoneal mesothelioma had low-dose exposure compared to 16% of patients with pleural mesothelioma in our study cohort