Preventing occupational asthma

• what makes an occupational disease ripe for prevention?

• what is the role of the academic/clinical community?

• what influences business?

Paul Cullinan - Pepys 2, Toronto

technological influences

aetiologic understanding

amenable risk factors

technology for reduction of risk factors

effective 2o

prevention

societal influences

frequency nature +

perception

individual costs

societal costs

corporate influences

frequency costs impact on workforce

impact on consumers

impact on reputation

competitiveness

influence of workforce

influence of consumer organisations

Factors influencing the prevention of occupational asthma

favourable

+/-

unfavourable

Approaches to the prevention of occupational asthma

• elimination• substitution• ‘molecular design’

• pre-employment eugenics

• exposure control• surveillance• (delivery)

first author

agent methods design

surveillance education exposure reduction

Drexler AA O X O

Liss AA ? ? O X O

Hunt latex O X O

Saary latex ? ? O X O

Allmers latex O O O X O O O

Tarlo/Liss latex O X O

Fisher LAA O X O

Botham LAA O O X O O

Tarlo NCO O O O X O O O

Juniper/

Cathcart

detergent enzymes

O O X O O

Studies of primary prevention

Y N ?

Studies of primary prevention: the effects of enhanced surveillance

0

10

20

30

40

50

60

70

80

90

'80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91 '92 '93

No

. ac

ce

pte

d c

laim

s

diisocyanate OA other OA

Tarlo and Liss

Incidence in studies of prevention

first author

agent incidence

Drexler AA

Liss AA

Hunt latex y (crude)

Saary latex

Allmers latex

Tarlo/Liss latex

Fisher LAA y (not stated)

Botham LAA y (?)

Tarlo NCO

Juniper/

Cathcart

detergent enzymes

Y N

Incidence and occupational asthma

risk

0 6 12 18 24 30 36m

time from first exposure (employment)

risk

unusually sensitive

exposure

• individual immunity ---- herd immunity• who is ‘at risk’?• group risk dependent on exposure and turnover• in a state of steady exposure risk depends on turnover

0

1 0

2 0

3 0

4 0

5 0

6 0

6 9 7 1 7 3 7 5 7 7 7 9 8 1 8 3 8 5 8 7 8 9 9 1 9 3

# ca

ses

0

1 0

2 0

3 0

4 0

5 0

6 0

av

era

ge

pro

tea

se

lev

els

(n

g/m

3)

Interpreting prevention studies

Exposure limits in occupational asthma

• something to aim at (NCO, subtilisins, bakery dust, amylase……..

but:

• very large # of agents• capturing relevant exposures is technically difficult• thresholds?• measuring biological allergens is technically difficult• SME’s don’t understand them• ‘of limited value in exposure control’

• have they ever ‘worked’?• in-house limits

first author Agent Exposure limits

Drexler AA

Liss AA

Hunt latex

Saary latex

Allmers latex

Tarlo/Liss latex

Fisher LAA

Botham LAA

Tarlo NCO external

Juniper/

Cathcart

detergent enzymes

internal

supermarket bakeries

Secondary prevention: how good is routine surveillance?

0 2 4 6 8 10

confectioner

manager

baker

all

% work-related chest symptoms with sp.IgE

surveillance

survey

2975

166

1556

80

370

30

1049

56

Incentives towards prevention

Sticks:

• the costs of a case…

• regulation

• reputation

Carrots:

• insurance premiums

• tax breaks

• what motivates industry?

• SME vs the large corporation

• (where is OA located?)

• occupational lung diseases in history

Barriers to prevention: a chief medical officer’s view

Paul,Thank you so much for the meeting yesterday. It was very interestingalthough I’m not sure it will change our practice. X’s parting shot to mewas that he didn’t see why we should investigate anyone for OA as the insurance companies would do it anyway and we might as well just dismiss employees with bakers’ asthma as it would probably becheaper in the long run.

We must admire the human race – etiquette demands it of us (Mark Twain)