Document EvpqpjEK6LQxpjderZY12LvkR
COMPAN'Y CORRESPONDED, CE
MAY 2 8
todiv: Corporate Environmental ServicesKROM DIV: Specialty Chemicals
location-. Morristown
location: Buffalo Dye Plant
att'N OF: SUBJECT:
Mr. W. S. Ferguson
date: ^ay 23,
Director - Occupational Health & Safety
VINYL CHLORIDE - PROPOSED OSHA STANDARD
1974
1. Based on Bio-Test/MCA data tFed. Reg. _39_ C92) 16896 (May 10, 1974) , we can make the following scale-up and extrapolations assuming a straight-line log dose/probit response.
dose rate
- 50 ppm
respiration rate (mouse) = .024 1/min.
respiration rate (man)
= 7.5 1/min.
weight (mouse)
= .025 Kg
weight (man)
= 70 Kg
incidence rate @ 50 ppm
= 2/200 = .01
upper 99% confidence level of .01 incidence =
.01 + 2.33 (S.D. of the incidence) =
.01 + 2.33
target incidence 10-5
.01 x .99
V 200
= probit .735
.0264 = probit 3.06
h-`
O 1 (T)
= probit .240
10-7 = probit -.20 10"8 = probit -.62
probit shift to reach targets (P#oi " Pt)
10~5 A p = 2.33 10"6 A p = 2.82 10"7 A p = 3.26 10~8 A p = 3.68
AS I 000017712
Mr. W. S. Ferguson Vi'nyl Chloride -* Proposed OSKA Standard
Page 2 May 23, 1974
1. (Cont'd.)
total dose/mouse =
.024 1 x 60 min, x 7 hr. x 5 d. x 4.33 wk. x 7 mo.
min^ x
hr. x d"! x wkTM x
mo.
1527.6 1 or x
= 76,4 ml of VCM
106
( 70 )2/3
(.025)
x 76.4 ml
15177 ml VCM
Extrapolation of the log dose/probit line involves the expression
A logi0 dose
AProbTt
=
thus A lo^io D = SAP
A log10 D
aT^
Slope (S)
or log10 Do " log10 D1 = SAP
logi0
D1
= SAP <=>r
x 10-sAp
sAp
10 or
Mantel-Eryan recommend S = 1 but a more realistic slope may be 0.4. Thus, for various target incidences (acceptable tolerance) and for the alternative slopes, we find
Target Incidence
(s)
Selected
Slope
(Dl)
Calc. Dose (ml)
Calc. cone. VCM in ppm (*)
10-5
1
71 .002
10~6
1
23 .0007
10~7
1
8.3 .00025
HO 1 CO
1 3.2 .00009
10"5 10~6
0.4 0.4
1775 1130
.053 .033
ASI 000017713
10~7
0.4
754
.022
o 1 CO
0.4 512
.015 (*) See next page
Mr. W. S. Ferguson Vinyl Chloride - Proposed OSHA Standard
Page 3 May 23, 1974
(*) In a working lifetime of 40 years, a man inspires
1000ml x 7.5 1 x 60 min, x 8 hr. x 235 d. x 40 yr.
' ~I x min.x
hr. x cL x yr\
33800 x 106 ml
Therefore ppm TLV = calc, dose x 10/33800 x 10 = calc, dose/33800
2. This is a discouraging picture and leads one to wonder where the holes in the logic reside. It is important to apply the most realistic slope and this may come out of the present studies. Relative retentionrates of man and mouse have not been taken into consid eration and this may be important. Most likely to affect the outcome would be quantitative differences in metabolic pathways and immuno logic responses.
3. If we extrapolate the data backward, using the above assumptions (slope = 0.4, 99% C.L.), we find that even at 2.7 ppm, the incident rate would be 50%. Since actual VCM may well have long been at this level or higher, there seems to be flaws in the logic or too much built-in conservatism. At a target rate equal to the observed (.01, i.e.Ap = 0), the TLV for man calculates on the same basis as 0.45 ppm. This is equivalent to saying that man is 100 times as sensitive as a mouse to VCM, an unlikely situation.
KHF:dmw cc: Dr. W. A. Knapp>'
K. H. Ferber Manager - Environmental Control
ASI 0000177U