HD 806/79

POSSIBLE HEAI,THHAZAROS FROM DIFFEREa'fl '.'YPES OF

~10RPHOUS SILICAS

SUGGESTED THRESHOr..D LIMIT VALt1ES .by

JØRGEN JAHR

Inst! tute of Occupational Beal th f Oslo

HD 806/79

FROM DIFFERE:NT '.'YPES OF

~10RPHOUS SILICAS

SUGGESTED THRESHOr..D LIMIT VALUES .by

JØRGEN JAHR

Inst! tute of Occupational Real th f Oslo

HD 806/79

3

'I \,¥\' i

:'

necessary alse te make an x-ray analysis of the' sample.

(Contrary to what is stated in the NIOSH Manual of

Analytical r.ethods ,se-cond ed! tien Volume 1" page 110-2,

amorphous silica does indeed interfere with the infrared determination of quartz and other chrystaline forms of silica). If the potassiurn bromide method has been used for the infrared analysis, the tablet may be dissolved in water and ths partie les coilected on 25 mm diameter Nuclepore filter which then may be used directly for

x-ray difraction analysis, see Altree-Williamsl) ,or

Edholm, Gylseth and Nicholson2~ A detailed description

of the x-ray difraetion method is given by Edho1m and

Nicho1son . 3)

HEALTll UAZARDS TO HUMAN BEINGS

Diatomaceous earth pneumoconiosis has be en described by

Sander4) in the second edition of Patty's "Industrial hygiene and toxicology." (This section has been removed in the third edition) . In a medical study, 869 workers from five plants were x-rayed and 786 had complete medical examinations and laboratory studies. The main conclusions were that 9 % of the 869 x-rayed workers showed changes consist~nt wi th a diagnosis of pneumoeoniosis / and that

those at work in the mills had a higher risk ~an those

employed in the quarries. The quartz-content in both crude' and milled diatomite averaged 2 %. Workers with massive

confluent lesio~s showed reduced pulmonary ventilatory function, but those with only linear or nodular changes

(on the x-ray film) showed no consistent pattern of disturbed lung function. This work was carried out by

Uni ted States Public Heal th Service. Sanders also si~es

a work by Smart and AndersonS) who concluded that inhalation of crude diatomite dust caused only øenign linear fibrosis with no symptoms or disability. Heavy exposure to calcined

diatomite, however, of ten caused rapidly progressive fibrosis.

There are conflieting reports among ferro-si1icon operators.

a single case ef sil1cosis at American ferro-silicon plants. panchery9) found slight f1brosis, but no

8illeosi s among the workers at ferro-silicon plants.

R~ing Pancherys material, Radica10)was also only

able to show reticulation, which had increased in two

cases. Neither Drees and Jungl1) nor Robert sl

2) have detected si11cosis among ferro-silicon workers, in spite of part1y heavy exposure to amorphous silica.

on the risk ofsilicosis Fehnel 8) did not find

Broch claimed that he had found 29 cases of silicosis l3)

and 30 suspect cases among 208 workers at Norwegian planta.

Five ef the cases had worked in a quartz quarry or in the quartz crushing department. One person had worked for 8 years in a foundry before working 8 years in the ferro silicon furnace-house. Unfortunately, the dust samples colleoted were only analysed chemically, so it is unknown whether the dust eontained crystalline silica.

GlØmme and swenssonl4), studied 865 workers from Norwegian

and S\'ledish ferro silicon-smelting plants.. They found

17 cases where the change in lung tissue corresponded to silicosis~ Of these, four had worked in the

atmosphere of the furnace-house. These four had slight changes on the lungs, and the authors conclude that the risk of lung dust disease due to the furnace-house

atmosphere itself seems to be moderate. i

Brucel5) was first to claimthe ',occurenoe of silicosis

in the manufacture of silicon alloys. Among a total 64 workers in two small smelting plants he claimed to_. have found io cases of s11ioos1 s. These cases were thoroughly re-examined by Swensson, Kvarnstrøm, Bruce, Edling and Giømme16) with the result that the diagnosis of silicosi s eould be maintained only in one of the

7

tissue reaction in -the lungs, which afterwards did not show any tendency to progress . These particles were substantially smaller than the quartz particles¡ O .15~m as a9ainst 1.2~m. The reaction to amorphous particles from a ferro-silicon smelting furnace was considerably

smaller than that from quartz, fused silica and the

silica produced by combustion of the silicon-halogen

compound.

Renewed animal experiments by GIØ~ne and Swensson14) with dust from ferro-silicon smelting furnace confirmed that this type of dust caused considerably less fi.brotic changes than quartz with particle size smaller than 5vm

(mean' value 1.2l.m), while quartz with particle size less

than O. 31Jm (mean val ue O .

121Jrn) was somewhere in between.

Some of the results are ii1ustrated in figures L and 2, (App. 2), giving the weight of respectively lunga and lymph nodes

as a function of time after injection. There seems to be a good correlation hetween the weight of these organs and the degree of fibrosls.

procnazka19) concluded that amorphous silica from electro- chemical high temperature prosesses not only caused major damase to cells (in vitro experiments), it also caused silicotic tissue reaction~ in animal tests. Be does not,

however, say anyth'ing about the degree of the silicotic. e'ffect and add.s tha,t further tests are necessary and that a justified occupational heal th judgement of the dust' conditions in the ferro-silicon indus'try was not possible at th,e time being.

i

swensson20) has investigated the fibroginetic effect of a special amorphous silicon dioxide obtained as a by-pro~uct in the production of aluminium fluoride . Animal experiments showed that the pai:'t~icles had an acute irritative effect and made it difficul t for the animals to breathe during the first 24 hours after injection. This is an unusual reaction

v.o,"

are in many cases ~xtrem81y 61d and have hean subjected to considerable pre88ur's r may be a180 some temperature..

~~his could ?robably explain the reported cases of s111c08is

from min ing and milling of diatoma,ceous earth, as the

infer:Lor amount of crystalline siliççi i normally about 2 % i doss not seem sufficient to explain these cases unless the exposure had' bean extrerne.

The available data is not adequate for setting up defini te t:hreshold limit valÜr,~s for the various arnorphcus silicas.

For th1s purpose H' trlOu1d be i'lscessa:ry to ha've the lifetime

dose, for instance' calculated as suggested by Jahr20) coupled with definite msdical diagnosis for each of many

persons not exposed to ('¡the!: fibr:tnogenic dusts. We are,

howåvery able to lDt:tke farely good "guesstimates" as given

in Appendix 3 ~ If these values are not exceeded¡ the :elsk of contracting 8111c03i8 seems to be extremely small.

.

Il

10) Radica, U.: UContributo alla studio sulla

pneumoconiosi da ferrosilico", Rass Med. Ind.ustrio.

3 ( 25): pp. 181 - L 8 5 ( 19 S 6) . ,

11) Drees and Jung, cited by Swensson et al.,

see 16)..

12) Roberts, W.C.: "The ferroalloy industry hazards of the aiioys and semi-metals", part Il, Jo. Occup..

Med. l, pp. ,7 L -7 7 ( 1965) .

13) Broch, C..: "Silicosis caused by the smoke dust in

a ferrosilicon and ferro-chromium smelting-plant",

(In Norwegian, with English sumary and English

text for tables and figures) , Olaf Norlis Forlag, Oslo 1953.

14) Giømme, J. and Swensson, Å.: "Risikoen for støvlunge- sykdom i ferrisilicium-smel teverkll, Del I - iV,

Yrkeshygienisk institutt, Oslo and Karolinska sjukhuset , Stockholm, 1965 - 66. Steneil..

15) Bruoe, T.; "The occurence of silicosis in the manufacture of si1icon alloys ", J. Indust. Hyg..

Texicol. 19, pp. 1$5-162 (1937).

-

16) Swensson, A., Kvarnstrøm, K., Edling, N.G.P. and

Giømme, . J.: "Pneumiconiosis in Ferrosilicon Workers -_i A Fellow-Up Studylf, J. oc~up. Med. lli ppo., 427-432 (1971).

17) Vitums, V..C., Edwards, M.J. and Niles, N.R.:

"pulmonary F,ibresis from Amorphous Si.lica Pust;

a Product of Silica Vapor". Arch. Environ, Health, pp. 62~67, March/Aoril 1977.

T~race eiie~ent~ PAH and Si02 l_n amor;L?hou~

slU.ca t,rom s.i.li.con and ferro-s:l.licon ;pr.odueti~t1.

E~2~_E~2Q~2~!~n_2£_§!:~~t~!

Institute of occupationai.Health~ E - S

~~i:-l~~:. _carent __~l:i:~~.~~_~~~____. _______E~£~~t:~_________ - - fÑot - the - - -- Paraiiels L ~~ Para~lels: l~ san s~le)

_0,00004

'1; i" "1.Q . . 19ì6 I I

ⁱ _0,00064 ^l

l i

ed

_0,00005 l^l _{0,00005 0,00043} ^li _{O ¡ 0005} .- 0,00(,1

O ,00p01 i^{i o(}

0,009

ⁱi

0,001

Ni o,oooSü ⁱi 0,00001 ^o(

o ,009 I';:

ⁱ

0,009 0,002

I

. '--'. ^-

,Pb 0,0016 ⁱr o ,oò52 ⁱi

0,001

0,0016

lⁱ

0,0016

O ,0060 ⁱi O ,006

0,002

! i

er

^o(

0,002

^{il o(}

0,004

^l

o(

0,002

^{ii o(}

0,002

^{-: O ,004 i o(l .. O , 004}

0,00091^{. i}

0,031

^.1

As ^{I I}

0,00087 ⁱi ^{O ,0009} 0,.036 ⁱi

0,034

V 0,000057 ^i,

0,0007

ⁱⁱ

0,000057 ^li

0,00006

0,0007 ^{lj O ,0007}

Co ^.: O i 0002 ⁱi 0,0044 ⁱl ^{O r 004}

0,001

~

0,0002

^{i, ..} _9-,..°0~. 0,0044 ^{i, O ,004} ... ^{O , 002}

PAH ⁱL ( 0,0002 ^!i _C=

0,2 1,3

! i

-

.

, . l

Tb'tl S102

-

^li

- -

_,^!

-

r 94 - 98

L i

~~2m_~2~~£É!2U_2~_I~_!_l~2!

^':

-. L

I

Cd 0,00012 ^il 0,00043 ^,L

0,00012 ⁱt

0,0001

0,00022 ^ll 0,0003 ^{.c O ,0001}

Ni O ,00046 ^íl i

0,004

^,i

0,02

O ,00040 ^{i '}l 0,0004

0,003

iⁱ

0,004

0,04 '

Pb 0,"012 ⁱi

0,022

^ll

0,005

0,012

^li

0,012 0,023

^{ii O 1023 O ,006}

.-

L

i

Cr 0,0016 ⁱ 0,0066 ⁱl ."

0,0016

^lI' 0,0016 ^{O ,0067 lI O ,0067}

As O . 0105 ^it 0;.14 ⁱl

0,0113 ^{' il}

0,011 0,14

^{i. 0,1.4}

,

--

V 0,000080 ^{lI O ,0009 li}

O ,000084 ⁱl O ,ooooS 0,0005 ⁱL 0,0007 ^.

i

i

Co ^~ 0,0002 ^l 0,0022 ^il

0,05

i 0,0033 ^l

0,003 ___._ 0,00..___

.( 0,0002 ^{l o(} O , 0~?1_ i

-

_{i ,}

PAn * l

0,0011

^l

^2,0

^{4,o't C}

l

(

^¡

^-

I !

.

Total 5i02

-

^,_,

- -

^l_i

-

86 - 90

J ⁱ

* 3 samples from a 'closed furnaca: 0.37, 0.24 and 0.65 % PAH.

Free crystalline silica could not ,be detected by x-ray analysis in any of the samples analysed by Institute. of Occupational Health.

Reproduced from HR1sikoen for støvlungesykdor i ferrosilisiumverk, del II. oyr.eeksperimentelle undersøkelser" by .Jon Glømme (t). 14)

g 6,'

S

ti ^""

¡¡

roi.

O' 3

oMr.

.t4-_{~ 2}

~~

)

ti 1 i:

.3

..

^{.. -A}

\,

~n~.¿

~t,'1

ct&

Si fur\'a.ce

, Dust fro'L Fe

control ani.mals

~

1 2 3 _l. 5

.6

7 8 months

Figol. Weight of the lungs as a function of t.imEl

after a single intratracheal injection of 40 mg quartz and dust from FeS! furnaces and for untre.ted control animals.

, ,

from reSi. furnaee

control animals _'I

Appendix 2

Fig.2. Weight of lymph nodes as a function of time after a single intratracheal injection of 40 mg quartz and dust from reSi furnace, and for untreated control animals.

3 ⁴ 5 6 7 ^{8 . months}

iot

SUGGESTED TLV' S FOR DIFFERENT SILICAS WITH PARTICLE SIZE ( 5~m.

Type note

^TLV

mg/m 3

Cristobali te (e)

o. i

0.1 0.2

Tridymi te (T)

ci-Quartz (Q)

Amorphous

silica from

productibn

of AlF 3 (A)

TLV set on basis

of irri tating

effect ^1.0

Diatomeaceous

earth (Kieselguhr) (D)

Wi th crystalline

silica ~2 %

1.5

Amorphous

silica from FeSi and

Si smelter (S)

precipi tated amorphous

silica (P) ,

Inert dust (I)

2.0

2. O

Nuisance dust

5. O

For mixtures:

TLV ⁼⁼ L

% C + % T + % O ₊ % A ₊ % D

+ ^% S + %

p

₊

% I

- - _-

10

20

_iOO

150 200 500