Beoordelen van piekblootstelling aan oplosmiddelen...5 TNO KvL, CGC bijeenkomst 12 maart 2009 ......

Liesbeth Preller

Beoordelen van piekblootstelling

aan oplosmiddelen Maar welke maat hanteren?

TNO KvL, CGC bijeenkomst 12 maart 20092

Used definitions

• Exposure based• ’High’ exposure during day

• ‘High’ exposure during longer period of time

• Rapid increase in exposure

• Health based• Period during which health effects occur

• Challenge of allergenic effects

• Reactive Airways Dysfunction Syndrome


Relevance

• Prevention of health effects due to peaks in

exposure

• (Effective) reduction of 8hr-TWA/dose by

reduction of exposure peaks


Background

• Role VOC peaks in Chronic Toxic

Encephalopathy suspected

• With similar dose, does exposure pattern with

peaks more harm than constant exposure?

• Do we (therefore) need standardization of

peaks? If yes, how?


‘Evidence’

• Not based on epidemiological data

• Toxicological data: some indications related to solvents

• Subjective acute effects sometimes in relation to chronic effects

• TNO study Bos et al., 1998

• Physiological Based PharmacoKinetic modelling

• Distribution of ‘mother’ compound over body tissues

• Comparison of realistic exposure scenarios with and

without peaks: PER, TRI, Toluene, Styrene

• High doses: peaks lead to higher brain and blood

concentrations


Study

• Evaluate ways to describe exposure profiles in

terms of peak exposure

• Measurements during spraying of VOC

• 27 workers, 15 companies in various sectors

• Direct reading instrument (PID)

• Charcoal tubes


Definition of a peak

Exposure above reference level


Peak characteristics

0 10 20 30

Time (min)

Ex

po

su

rele

ve

l Maximum peak

Reference level

Average peak=[E(A) + E(B) + E(C) + E(D) + E(E)]/5

A

B

C

Duration

of peak

Time between peaks

Number of peaks per hour = 6

Ratio=mean maximum

peak / mean average peakD

E


Peak measures

• Variation in reference level:

• TWA exposure during sampling

• OEL mix during sampling

• Variation in averaging time:

• 5 seconds

• 1 minute

• 15 minute

• Total of 36 peak measures


Averaging times

0 50 100 150 200 250 300 350 400 450 500

Time (sec)

Concentration

VOC (ppm)


Results - basic information

AM (SD )AM (SD )AM (SD )AM (SD ) R angeR angeR angeR ange

D uration (m in)D uration (m in)D uration (m in)D uration (m in) 46.5 (29)46.5 (29)46.5 (29)46.5 (29) 4.6 4.6 4.6 4.6 ---- 159 159 159 159

TW A exposure (ppm )TW A exposure (ppm )TW A exposure (ppm )TW A exposure (ppm )

78.4 (73)78.4 (73)78.4 (73)78.4 (73) 6.8 6.8 6.8 6.8 ---- 341 341 341 341

O ELm ix (ppm )O ELm ix (ppm )O ELm ix (ppm )O ELm ix (ppm ) 78.9 (68)78.9 (68)78.9 (68)78.9 (68) 26 26 26 26 –––– 288 288 288 288


Influence of reference value and

averaging time

Param eterParam eterParam eterParam eter AMAMAMAM O EL O EL O EL O EL vs vs vs vs

TW ATW ATW ATW A

longer av. longer av. longer av. longer av.

tim etim etim etim e

# peaks/hr# peaks/hr# peaks/hr# peaks/hr 1 1 1 1 –––– 71 71 71 71 <<<< <<<<

duration (sec)duration (sec)duration (sec)duration (sec) 33 33 33 33 –––– 1601 1601 1601 1601 >>>> >>>>

tim e betw een (sec)tim e betw een (sec)tim e betw een (sec)tim e betw een (sec) 32 32 32 32 ---- 792 792 792 792 >>>> >>>>

m axim um (ppm )m axim um (ppm )m axim um (ppm )m axim um (ppm ) 106 106 106 106 –––– 161 161 161 161 ==== ====

average (ppm )average (ppm )average (ppm )average (ppm ) 96 96 96 96 ---- 111 111 111 111 ==== ====

ratioratioratioratio 1.2 1.2 1.2 1.2 ––––2.42.42.42.4 >>>> ====


Exposure profile per sector

(OELmix, 5 sec.)

0 200 400 600 800 1000 1200 1400

Time (sec)

To

tal V

OC

co

nce

ntr

ation

Wood assembly

Spray painting of

transportation means

Glass-reinforced

plastics industry


Data analysis

• Principal components analysis

• 24 peak measures (15 min. values excl.),

plus TWA exposure during spraying


Principal Components Analysis

Com ponentCom ponentCom ponentCom ponent EigenEigenEigenEigen----

valuevaluevaluevalue

% Explained % Explained % Explained % Explained

variancevariancevariancevariance

VariablesVariablesVariablesVariables

1111 12.512.512.512.5 50505050 TW ATW ATW ATW A

m axim umm axim umm axim umm axim um

average average average average

2222 4.64.64.64.6 19191919 tim e betw een peakstim e betw een peakstim e betw een peakstim e betw een peaks

3333 3.33.33.33.3 13131313 # peaks/hr# peaks/hr# peaks/hr# peaks/hr

durationdurationdurationduration


Concluding remarks

• Results are situation specific

• Strategy can be used for variable reduction in description of

exposure scenario

• Improvement of exposure-response studies

• Input for standard setting for specific exposure indices

• Little evolution with regard to peak exposure, e.g. REACH.

Beoordelen van piekblootstelling aan oplosmiddelen...5 TNO KvL, CGC bijeenkomst 12 maart 2009 ......

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