ENGINEERING AND
MANUFACTURING STAFF
November 19, 1971

Cowpany

To: Mr. J. U. Damian
Mr. B. H. Simpson

cc: Mr. H. H. Brehob Mr. R. C. Ronzi
Mr. D. A. Jensen Mr. G. H. Schwartz
Mr. H. L. Misch

Subject: Fibrous Asbestos Ehisaions

On October 19, 19?1, the State of Illinois held a public hearing
concerning the banning of asbestos in brake-linings beginning with the
1975 model year. At this hearing, the State of Illinois requested a
statement from Ford Motor Company regarding the banning of asbestos.

Mr. Damian is in the process of preparing a statement for filing on
November 22, 1971. The purpose of this letter is to provide a summary of
available information concerning asbestos, for background or reference use,
covering the following tepics:

1. The effects of asbestos on health

2. Sources of ambient fibrous asbestos

3. automotive uses versus total asbestos consumption
h. Ford studies to determine asbestos emission rates

5. Alternatives for asbestos in brakonlinings
1. Health Effects

Inhalation of fibrous asbestos has been considered the source of asbestosis
and mesothelioma (rare form of cancer frequently observed in asbestos workers).
Non-fibrous asbestos, on the other hand, is believed to be harmless to human'
health. The mechanism by which fibrous asbestos promotes cancer formation has
not been determined, however, it is conjectured that synergistic effect of
asbestos with various pollutant (such as cigarette smoke) is the major cause.
Asbestos induced cancer is limited to those who work in asbestos mines or
industries which produces asbestos products or those who live in the vicinity
of asbestos mines and asbestos processing industries (9.3. industrial processes
in which workers actually come in contact with fibrous asbestos). A high
prevalence of asbestosis has also been observed among consturction workers who
specialize in spray insulation of buildings. The contraction of this type of
cancer usually results from a 15-30 year of exposure and the frequency of
cancer occurrence is related to the dosage of fibrous asbestos which is many
orders of nagnitude higher than that observed in ambient background air.

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2. Sources

The fibrous asbestos content of Detroit's ambient air is estimated to be
about 1 10-3 grass/m3. A recent literature review by the Public Health
Service states that the bulk of airborne asbestos originates from natural
sources such as soil dust and locally from asbestos mines and processing
plants. Limited amounts of fibrous asbestos are also emitted from the use
of asbestos cement used often as spray building insulation. According to
another revieu,by the National Research Council, automotive contribution
from brake-linings is believed to be negligible because asbestos fibers
are destroyed by the intense heat created by the braking process (about
1h000F) to a non?fibrous state.

3. Uses

The total s. asbestos production in 1965 was 8 105 tons. Cement,
floor tile, paper, and other building construction materials accounted for
about 90% of asbestos consumptiOn. Friction materials - - primarily brake
linings - - accounted for 2.8 10? tens or 3.5% of the total asbestos
production.

Brake gining Emission Rates

Attempts have been made at Ford to determine the fibrous asbestos emission
rates from a laboratory brake-lining test stand. An elaborate electron
microscope technique is used to identify the tiny fibers (about 1 10'6
inches diameter). Our preliminary experiments indicate that there is very
little fibrous asbestos present in brake dust. The fibers are less than
0.5 in length and most of them are converted to a non-fibrous state by
the process of braking. Our emission rate estimate is very close to the
background ambient concentration levels.

5. Brak inin Alternate Materials

Alternatives for asbestos based linings are few and all have some disadvantages
in terms of either performance, cost, or both. Ford has been using cermet
linings (sintered metal) for heavy duty trucks and semi-met (metal strand and
carbon mixture) for police cars both containing no asbestos. Beginning with
the 1971 model year Ford has been supplying optional semi-met front-end
brakes for police car fleets. Semi-met linings are superior in performance

to conventional brake-linings (about equivalent in terms of cold-wear and
noise), but the cost penalty is severe Just for front-end brakes).
Ford is experimenting with semi?mot linings for rear wheels. However, there
are some cold-stopping and wear difficulties associated with rear wheel semi-mot
linings in their present form and may necessitate major redesigning of the rear
wheel brake systems682263



 

 

 



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