Three hundred and thirty three questionnaires were distributed to all sampled schools. Table VIII presents distribution and response rates at each individual school.
One hundred and thirty-nine questionnaires were returned.
Of these, 20 respondents did not use the duplicator at all,
CORROBORATION OF MIRAN MEASUREMENTS
USING METHANOL DETECTOR TUBES
Detector Tubes
1.200
1.000
800 600 400 200 •B- --'::::--"^
Za-^" ''"
...g--S-*'...ͤ
200 400 600 800 1,000
Miran Measurements
Detector Tubes Reference
Mean dnerence between mettndt: 17.11 ppm
CORROBORATION OF MIRAN MEASUREMENTS
USING PERSONAL SAMPLES COLLECTED ON SILICA GEL
Silica Gel
1,000
800 600 400 200..."""*•'•••"...w
D.^.^.
.ͣ•ͣ•ͣͣ-"...ͣ--^,-^-^-'...D...
»-«£'»!.-....-...__«...~...>...-...-...
DJ___________L
200 300-400 500 600 700 800 900
Miran Measurements
SicaGel Reference
Mean dfferenM betwMn methods: ai19 ppm
QUESTIONAIRE RESPONSE RATES
SCHOOL
NUMBER DISI ROUTED
NUMBER RblURNED
PERCENT RESPONSE
A
80
29
36
B
78
27
35
C
80
34
43
D
75
38
51
E
20
11
55
333 Questionaires Distributed,
55
questionnaires were thoroughly completed, therefore,
responses for particular questions usually do not add up to
119. Figure VIII provides a graphical representation of the
percentage of responses coming from each school. Because schools C and D had favorable response rates, 43% and 51% respectively, responses are somewhat weighted in favor ofthese schools. School E also had a high response rate
(55%), however, since the principal requested that only 20
questionnaires be distributed to targeted workers, responses
from this school made up only 10% of the entire set of
results.
Proximity To Duplicator During Operation As described in the experimental methods section,
sampling was conducted as near to the breathing zone of.
workers as possible. However, movement among workers in the
vicinity of the duplicator may have created some disparities between actual BZ concentrations and air concentrationscollected through stationary sampling inlets. In order to
assess the importance of this difference, workers were asked
to describe:1) the distance between themselves and the
duplicator when using the machines, and
2) the percentage of time spent standing adjacent
PERCENTAGE OF QUESTIONNAIRE RESPONSES FROM
DUPLICATOR USERS BY SCHOOL OF ORIGIN
B 16.0%
27.0%
it
Total nimber of respondents whkdi use the
8piiitciupfcalor = 119
A 18.0%
A bar graph of the distribution of responses to these questions is provided by Figure IX. Thirty-four percent selected 3" as the distance separating them from the duplicator during operation. This answer was closely •followed by 6", accounting for 32% of all answers to this
question. A clear majority of 82% reported standing
adjacent to the duplicator 100% of the time required to run copies. Therefore, placment of stationary sampling inlets adjacent to duplicators will result in measurements which adequately approximate BZ exposures.
Average Exposure Duration Per Day
When workers were asked to estimate the average time spent using the duplicator per day, 75 responses produced a
mean duration of 14.33 minutes with a standard deviation of
20.07 minutes and a median of 10.00 minutes. However, when
responses were separated by job classification, a marked difference between distribution parameters was apparent. The average exposure duration distribution described by
teachers appears in Figure X. Their answers indicate a mean exposure duration of 9.04 minutes per day with a standard deviation of 9.64 minutes and a median of 7 minutes. The distribution of exposure durations for teaching assistants produces a mean twice that of teachers at 18.00 minutes
(standard deviation = 14.82). The median exposure duration among teaching assistants was 15.00 minutes. This
PERCENTAGE OF TIME SPENT
ADJACENT TO DUPLICATOR DURING OPERATION
(number Of responses » 93)
Percent of time
29%
DISTANCE BETWEEN WORKER AND DUPUCATOR
OURINQ OPERATION
(numb«r of fnpontNB B 93)
Distance Cnches)
90% 79% 100% 0 8 6 >6L-..1.,,..,, j . i .
-Ji 1 1 .1, 1___. 20 40 eoFrequency of responses
10 IS 2D 25 30Frequency of response
35Frequency
14
AVERAGE EXPOSURE DURATION PER DAY
_L ± I
a54.5 a5-1Z5 1&5-2a5 24.5-2a5 3a5-36.5 4a5^.5 4S.b^SL5 56.&^.5
4.M.5 125-1&5 2a5-24.5 2a&^3Z5 3ft5^5 44.&4a5 52.5^a5
Minutes
Number responding
39.00Mean (minutes)
ao4Standard Deviation
9.6460
distribution is presented in Figure XI. Clerical workers reported the largest exposure duration represented by a mean of 48.75 minutes with a standard deviation of 67.87 and a
median of 20.00 minutes. Table IX provides a summary of all
of the above parameters by job classification.Maximum Exposure Duration Per Day
The pharmacodynamics of methanol poisoning, as
previously discussed, are such that high, acute exposures
may result in serious irreversible effects. Consequently,
maximum exposure durations are likely to be of equal or greater physiological significance than average exposure durations. When workers were asked to estimate theirmaximum exposure duration per day, not surprisingly, the
same distinct differences by job classification resulted.Figure XII illustrates the maximum exposure distribution
described by teachers. Among this group of workers,responses produced a mean of 18.28 minutes with a standard deviation of 25.39 minutes and a median of 10.00 minutes. Teaching assistants reported a mean of 32.97 minutes with a
standard deviation of 40.91 and a median of 20.00 minutes.
The distribution of these responses appear in Figure XIII. Table X presents a summary of all distribution parameters by
job classification, including clerical workers, which was
represented by a mean of 53.40 minutes with a standard
Frequency
8
a -
4 -
TEACHING ASSISTANTS
AVERAGE EXPOSURE DURATION PER DAY
-...
___________ '
^^
. i... A.,.,
...J.___ iHI 1
1
a&4.5 &5-1Z5 ia5-2a5 245-2a5 3Z&^5 40.5^5 4a5^5 5&5^.5
4.5^5 1Z5-1615 2a^2i5 2a5^5 d&5^5 44&4a5 525^5
Mimites
Number responding
29.00Mean (minutes)
18.00Standard Deviation
14.82AVERAGE EXPOSURE DURATION PER DAY
Teachiers
Teaching Assistants
Clerical Worlcers
**Total
Number Responding
39.00
29.00
4.00
75.00
Mean (minutes)
9.04
18.00
48.75
14.33
Standard Deviation
9.64
14.82
67.87
20.07
l\^edian (minutes)
7.00
14.00
20.00
10.00
*'niis includes respondents that use the
Frdquency
30TEACHERS
± ± ±0.5-8.5 16.5-24.5 32.5^.5 48.5^.5 64.572.5 80.5-88.5 96.5-104.5 112.5-120.5
8.5-16.5 24.5-32.5 40.5-48.5 56.5-64.5 72.5-80.5 88.5-96.5 104.5-112.5
MinutesWorkers were asked to descrSie the maximum
amount of time they sport usiig the dupBcalor
on a daly basis.
Number responding
47.00Mean
18.28Standard Deviation
23.59Frequency
12
MAXHIKIM EXPOSURE DURATION PER DAY AMONQ TEACHINQ ASSISTANTS
10 -
I I
± ±
G5-125 24w&^5 48.5^5 72.5^.5 9a5-1(]&5 12a&^1325 1415-1Sa5 16a5-180.5
1Z5-24.5 3&&^5 ea5-7Z5 84.&«a5 108L5-12a5 13Z5-144wS 15&5-16&5
Minutes
Number respondrig
34.00Mean (minutes)
32.97Standard Deviation
4a9iMAXIMUM EXPOSURE DURATION PER DAY
Teachers
Teaching Assistants
Clerical Wortrers
**Totai
Number Responding
47.00 34.00 5.00 90.00l\fean (minutes)
18.28 32.97 53.40 25.08SlEuidard Deviation
23.59 40.91 77.25 35.77l\^lan (minutes)
10.00 20.00 30.00 15.00*ail respondents answering this question.
Daily Use Patterns
Since all sampling was conducted early in the week
(either Monday or Tuesday), it was necessary to evaluate any
bias introduced by excluding certain days of the week. With
this objective in mind, workers were asked if their use of
the duplicator followed any regular pattern throughout the
work week. Forty respondents (39%) answered that they did
follow a regular weekly pattern of use, while 63 (61%)
answered that they did not. Among pattern users, a large
interday variation was not seen, however, there was somewhat
heavier use of the duplicator on Monday. Figure XIV
presents average daily use among pattern users and Figure XV
presents the same information for individual schools. The
mean exposure duration among pattern users was 14.35
minutes.
Work Practices Related To Skin Exposure
Because methanol can penetrate the skin, an evaluation
of overall exposure to duplicator fluids would not be
complete without some consideration of skin exposures. In
addition to breathing methanol vapors, workers handle
methanol when transferring fluid from gallon fluid
containers to duplicator reservoirs. Skin exposure may
AVERAGE DAILY USE AMONG PAHERN USERS
Minutes
...^.jmamnm :SSffft¥5f^5f::*Wfe5: kVJVO».*.W.V.VA>'.WA'A-(, , ^^^ ͣJMM.I .Wjiai .Mjli |f<JII|,Mjm yi
...
Days
MONDAY ͣ TUESDAY s
DaR/paltems nustraled above represent the
answers of 40 (39^ which said Iheiruse of the
dupScfltor Mtowed a daily pattern.
MINUTES
100
80
60
40
AVERAGE DAILY USE PAHERN BY
INDIVIDUAL SCHOOL
20 - iMiM n<'fWv'«**''i*i'^vH iAM&im\,mmii ;S«¥S¥SMONDAY
TUESDAY WEDNESDAY THURSDAY
SCHOOL
FRIDAY
copies are carried back to the classroom, as well as to the
hands and fingertips during collating and handling finished
materials. Two questions directed at exposure during
transfer of fluids were:
1) How often do you personally fill up the
duplicator reservoir?
2) How often do you spill duplicator fluid on your
hands when filling the reservoir?Figure XVI illustrates the frequency of responses to these
questions. Although answers were highly variable, the
majority selected "seldom" as their response to both
questions.
Exposure to Methanol Vapors During Activities Other Than
Duplicator Operation
Workers also receive exposure to methanol vapors while
involved in activities other than duplicator use. A review
of Table III, which describes sampling sites, illustrates
the multiple use of duplicator areas. Of the eleven sites
sampled, only A-2 was used exclusively for duplicating and
had no other regularly occupied adjacent area.
In addition, some workers remain near the duplicator to
collate materials. Sixteen respondents said they collated
materials in the area of the duplicator. Forty nine workers
reported using the duplicator area for other activities.
The average time spent on other activities was 25.03 minutes
WORK PRACTICES RELATED TO SKIN EXPOSURE TO FLUIDS
FREQUENCY WITH WHICH WORKERS FILL FREQUENCY WITH WHICH DUPLICATOR FLUID IS
DUPLICATOR aUIDRESEVOIR SmiED ON WORKERS'HANDS DURING FILUNG
(number of iwpondwite Bill] (number of iwpondente am)
Seldom
10 20 30 40
Frequency of response
Occasionally
often located in lounge areas and work rooms, activities commonly described were eating, using office equipment, meeting with other workers and/or using the phone or rest room. At three of the sampled schools, workers were in the area of the duplicator their entire work shift, since their offices were located in this area.
III. Probability of Exceeding an Occupational Exposure Limit