Document r6ej86K7OBVD6g9yKrNd65Kgr
COMPAN'Y CORRESPONDENCE
W. A !<
MAY 2 8 1974
todiv: Corporate Environmental Service^RM DIV: Specialty Chemicals
location: Morristown
location: Buffalo Dye Plant
att'n OF: Mr. W. S. Ferguson
date: May 23, 1974
Director - Occupational Health & Safety SUBJECT:
VINYL CHLORIDE - PROPOSED OSHA STANDARD
1. Based on Bio-Test/MCA data (Fed. Reg. 2. C92) 16896 (May 10, 1974) , we can make the following scale-up and extrapolations assuming a straight-line log dose/probit response.
dose rate
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.i3 :*y-oi2oQ-" * 264 =prbit 3*6
target incidence 10"5 probit
.735
10~6 = probit .240
10"7 = probit -.20 IQ'8 = probit -.62
probit shift to reach targets (P.oi " 10"5 A p = 2.33
10"6 A p * 2.82
10"7 A p * 3.26
10-8 A p = 3.68
C-236 0-S1! PTC. IN l4.r A . (^
ASI 000010265
Mr. W. S. Ferguson Vinyl Chloride - Propose*. OSHA Standard
Page 2 I 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 wk. x
mo.
1527.6 1 or x
- 76.4 ml of VCM
106
( 70 )2/3 (TUTS) x 76.4 ml = 15177 ml VCM
Extrapolation of the log dose/probit line involves the expression
thus
A lo9l0 dose ^ probit
A logic D * sAp
Aigio d Ap
*= Slope (S)
or log10 Do " lo9io D1 = sAp
A
lgj.o Do sAp or
sAp 10 or
D1 * D0 x 10~S^P
Mantel-Bryan 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
10-5
(S) Selected
Slope
1
(Di) Calc. Dose (ml)
71
Calc. cone. VCM in ppm (*)
.002
10-6
1
23 .0007
10-7
1
8.3 .00025
10-8
1
3.2 .00009
10~5
0.4
1775
.053
10"6 10"7
0.4 0.4
1130 754
033 .022
ASI 000010266
10"8
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
lOOOral x 7.5 1 x 60 min, x 8 hr. x 235 d. x 40 yr = 33800 x 106 ml
I x min.x
hr. "x cC x yx~.
Therefore ppm TLV = calc, dose x 106/33800 x 106 = 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 retention^ates 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) f 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 000010267