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Administrative data

Endpoint:
additional toxicological information
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well documented study, No standard method availbale

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report date:
2010

Materials and methods

Type of study / information:
Assessment of biopersistence of respirable, fiber-shaped particles that result during the use of copper slag as an abrasive medium based on dissolution in an aqueous environment and physiologic saline solution.
Principles of method if other than guideline:
Test material was suspended for various periods of time in water and physiologic saline solution at 40ºC. Aliquot parts of this suspension were to be collected at defined times and examined for respirable fiber-shaped particles. Comparisons between the fiber counts detected immediately after preparation of the suspensions and the fiber counts after 14 and 24 days were to allow us to draw conclusions on the bio-persistence of fiber-shaped particles.
GLP compliance:
no
Remarks:
other quality assurance

Test material

Constituent 1
Reference substance name:
slag, copper smelting
EC Number:
266-968-3
Cas Number:
67711-92-6
IUPAC Name:
slag, copper smelting
Details on test material:
Sample representative for Type I Slag granules, primary was collected after use as abrasive medium ( Nastra used M 1 2/3)

It consists predominantly of particles with a diameter of 0.2 – 1.0 mm. The proportion of the particle fraction < 0.1 mm is 2.90 mass %.

The sieve fraction < 0.1 mm was used for testing.

Results and discussion

Any other information on results incl. tables

Characterization of the fiber-shaped particles detected in the suspensions

Most of the identified fiber-shaped particles have a length of 5 - 15 μm and a diameter of 0.5 – 1 .0 μm. There are also isolated cases of shorter and longer as well as of thinner and thicker fibers.

Typical for the fiber-shaped particles occurring in the test material are element peaks of oxygen, silicon and iron. Sodium, potassium, magnesium and calcium are not detectable, or only detectable in very low quantities. Aluminum is generally not detectable.

Fiber counts

The suspensions, when prepared, were found to contain an average of 1110 fiber-shaped particles per ml of suspension in water and 1068 fiber-shaped particles per ml of suspension in physiologic saline solution, as in Table 2.

After 14 days, no fiber-shaped particles were detectable in the suspensions (see Table 1).

After 24 days, low fiber counts were detectable in the suspensions (see Table 1).

Element composition of the respirable fiber-shaped particles

The element composition of the fiber-shaped particles in the particle fraction < 0.1 mm was investigated. In addition to carbon and gold peaks, which are caused by the filter material and the gold coating, these EDX spectra show peaks of the elements oxygen, silicon and iron.

 This suggests that the fiber-shaped particles consist almost entirely of iron silicate.

It is not possible to determine a carcinogenicity index (KI) pursuant to TRGS No. 2.3[[Technische Regeln für Gefahrstoffe− Technical Rules for Hazardous Materials]]because the amounts of the elements sodium, potassium, boron, calcium, magnesium, barium and aluminum that are required for such a determination are very low and lie under the detection limit in most cases.

Table1. Respirable fiber-shaped particles in the sieve fraction < 0.1 mm from used slag “NASTRA used M 1 2/3”

Experimental conditions

   

Internal sample number

 

Test duration

 

pH value of suspension (at 30°C)

 

Fiber count per tested filter field

 

Fiber count per filter

 

Fiber count per ml solution

 

Fiber count per 500 ml

 

Fiber count mil-lion per g of sieve fraction < 0.1 mm

Blind value, water

10/258-1-01

< 1 hour

6.9

0

 

 

 

 

Suspension in water, room temperature

 

10/258-1-12

< 1 hour

6.9

11

6,911

691

345,575

6.91

10/258-1-13

< 1 hour

6.4

21

13,195

1,319

659,734

13.19

10/258-1-14

< 1 hour

6.5

21

13,195

1,319

659,734

13.19

Suspension in water, 40º C

 

10/258-1-18

14 days

6.8

0

 

 

 

 

10/258-1-19

14 days

6.4

0

 

 

 

 

10/258-1-20

14 days

6.4

0

 

 

 

 

10/258-1-24

24 days

6.9

2

1,257

126

62,832

1.26

10/258-1-25

24 days

6.4

3

1,885

188

94,248

1.88

10/258-1-26

24 days

6.4

2

1,257

126

62,832

1.26

Suspension in physiologic saline solution, room temperature

10/258-1-15

< 1 hour

6.2

18

11,310

1,131

565,486

11.31

10/258-1-16

< 1 hour

6.2

14

8,796

880

439,823

8.80

10/258-1-17

< 1 hour

6.3

19

11,938

1,194

596,902

11.94

Suspension in physiologic saline solution, 40º C

 

10/258-1-21

14 days

6.2

0

 

 

 

 

10/258-1-22

14 days

6.2

0

 

 

 

 

10/258-1-23

14 days

6.3

0

 

 

 

 

10/258-1-27

24 days

6.1

1

628

63

31,416

0.63

10/258-1-28

24 days

6.2

2

1,257

126

62,832

1.26

10/258-1-29

24 days

6.3

1

628

63

31,416

0.63

Applicant's summary and conclusion

Conclusions:
The test demonstrated after 14 days no fiber-shaped particles with the critical dimensions are detectable and after 24 days only a very few are detectable. These findings suggest that the biopersistence of respirable, fiber-shaped particles that result during the use of copper slag as an abrasive medium should be classified as low.

Consequently it is to be expected that these particles are not carcinogenic when inhaled.
Executive summary:

The importance of biopersistence of fiber-shaped particles is apparent on the basis of the following considerations: the longer a fiber can exert its irritant effect in a sensitive area of the lung or pleura, the higher the probability that the tissue at the affected site degenerates and, in consequence, forms a tumor. However, the sooner a fiber-shaped particle dissolves or decomposes, i.e. the lower the particle’s biopersistence, the lower the probability of tumor formation.

The goal of the investigation conducted here was to find out with relatively simple means if the respirable fiber-shaped particles that result during the use of copper slag as an abrasive medium dissolve in an aqueous environment. The sieve fraction < 0.1 μm from copper slag used as an abrasive medium was in-cubated 24 days at 40º C in deionized water and physiologic saline solution.

The test showed that after 14 days no fiber-shaped particles with the critical dimensions are detectable and after 24 days only a very few are detectable. These findings suggest that the biopersistence of respirable, fiber-shaped particles that result during the use of copper slag as an abrasive medium should be classified as low.

Consequently it is to be expected that these particles are not carcinogenic when inhaled.

With the fiber-shaped particles found in the sample tested it is not possible to determine the carcinogenicity index (KI) pursuant to TRGS 905 No. 2.3 because the levels of the elements sodium, potassium, boron, calcium, magnesium, barium and aluminum required to determine KI are very low in these particles and mostly lie under the detection limit. KI is frequently used as a measure of the biopersistence of inorganic fiber-shaped dusts. The lower this index, the higher the biopersistence and consequently the carcinogenic potency of these dusts.

In Paragraph (4) of TRGS 905 No. 2.3 it is stated that the biopersistence of glass WHO fibers can also be estimated by means ofin vivoexperiments with intratracheal instillation. If its half-life is more than 40 days, the fiber is classified as a carcinogenic substance of category 3 (materials which are of concern in humans due to possible carcinogenic effect, however sufficient information is not available for a satisfactory assessment).

The results of the present testing imply that the half-life values of the fiber-shaped particles detectable in the tested copper slag in aqueous solution underin vitroconditions are significantly lower than 40 days. Under the assumption that underin vivoconditions the half-life values are significantly lower than 40 days as well, we conclude that the respirable fiber-shaped particles that result during the use of copper slag as an abrasive material should not be classified as carcinogenic.