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Toxicological information

Epidemiological data

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Administrative data

Endpoint:
epidemiological data
Type of information:
other: clinical field study in workers
Adequacy of study:
weight of evidence
Reliability:
other: Reliability was not assessed, because the publication was considered acceptable due to the fact that it served as a basis for OEL setting.

Data source

Reference
Reference Type:
publication
Title:
Potential nephrotoxic effects of exposure to silver.
Author:
Rosenman, K.D.; Seixas, N.; Jacobs, I.
Year:
1987
Bibliographic source:
British Journal of Industrial Medicine 44, 267-272

Materials and methods

Study type:
cross sectional study
Endpoint addressed:
repeated dose toxicity: inhalation
Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
A cross sectional study was conducted on workers engaged in manufacturing precious metal powder. Of the 27 workers, 96 % had raised urine silver concentrations and 92 % had raised blood silver concentrations. 19 % also had raised urine cadmium concentrations. The study examines the chronic effects of exposure to silver concentrating on the effects on renal function.
GLP compliance:
no

Test material

Constituent 1
Reference substance name:
Silver nitrate
EC Number:
231-853-9
EC Name:
Silver nitrate
Cas Number:
7761-88-8
IUPAC Name:
silver(1+) nitrate
Constituent 2
Reference substance name:
silver oxide
IUPAC Name:
silver oxide
Constituent 3
Reference substance name:
Silver chloride
EC Number:
232-033-3
EC Name:
Silver chloride
Cas Number:
7783-90-6
IUPAC Name:
silver(1+) chloride
Constituent 4
Reference substance name:
silver cadmium oxide
IUPAC Name:
silver cadmium oxide
Constituent 5
Reference substance name:
silver metal
IUPAC Name:
silver metal
Details on test material:
Name of test material (as cited in study report): the company in which the study was undertaken produces silver nitrate, silver oxide, silver chloride and silver cadmium oxide powders; in addition silver metal ingots are produced.

Method

Type of population:
occupational
Ethical approval:
not specified
Details on study design:
METHOD OF DATA COLLECTION
Type: Questionnaire / Work history / Clinical tests
Details:
- Testing consisted of a detailed questionnaire.
- Slit lamp examination was conducted by an ophthalmologist (conjunctival and corneal finding were coded on a 1-4 scale).
- Measurement of weight, urinary concentration of silver and cadmium, blood silver concentration, blood chemistry including blood urea nitrogen, and creatine and urinary n-acetyl-B-D glucosaminidase (NAG). Estimated creatine clearance was calculated. Analysis for cadmium, silver and NAG were performed on spot urine samples. Urine silver and cadmium levels were reported as micrograms of metal per litre of urine. For all analysis relating urine metal concentrations with health effects, however, the urine metal levels were corrected for urine concentration by expressing them as micrograms of metal per milligram creatine.
- An additional analysis of the effect of silver on NAG and creatinine clearance was conducted by comparing urinary NAG in the group as a whole with results of NAG in an unexposed control population consisting of the first 28 of 51 male workers from a tungsten carbide machine shop who were being studied for effects of tungsten carbide and cobalt.

SETTING:
- The company in which the study was undertaken produces silver nitrate, silver oxide, silver chloride and silver cadmium oxide powders; in addition silver metal ingots are produced.
- About 220 workers are employed at the plant (incl. 30 maintenance workers and 150 in production).

STUDY POPULATION
- All employees who had worked for at least two years in silver flake, silver nitrate, silver powder, or the refinery area.
- Maintenance workers who had worked for more than five years at the plant-
- Workers from any area who had worked for more than 10 years were asked to participate and 27 workers agreed to do so.

COMPARISON POPULATION
- Type: control or reference group.
- Details: unexposed control population consisting of the first 28 of 51 male workers from a tungsten carbide machine shop who were being studied for effects of tungsten carbide and cobalt.

Exposure assessment:
measured
Details on exposure:
A federal Occupational Safety and Health Administration health inspection was conducted at the plant and time weighed exposures to silver ranged from 0.04 – 0.35 mm/m3.
Statistical methods:
Multiple regression analysis

Results and discussion

Results:
FINDINGS
- Of the 27 workers, 96% had raised urine silver concentrations (range 0.5-52.0 µg/l, mean 1.3 mg/l).
- 92% of workers had raised blood silver concentrations (range 0.05-6.2 µg/100 ml, mean 1.0 µg/100 ml).
- 90% had raised urinary cadmium concentrations (range 1.9-76.0 µg/l, mean 11.8 µg/l).
- Most workers had symptoms of respiratory irritation; nose bleeds were reported in 30%.
- Deposition of silver in the cornea and conjunctivae of the eyes was observed in five of eight long-term workers (63%).
- In total, 10 of 27 workers (37%) showed conjunctival deposition, and 6 of 27 workers (22%) corneal deposition of silver.
- Although not statistically significant, corneal deposition was associated with complaints about decreased night vision.
- The urinary enzyme NAG was significantly raised in four individuals and was correlated with blood silver concentrations and age.
- Average NAG concentrations were significantly higher in silver exposed subjects than in the control population.
- Estimated creatinine clearance was significantly lower in the silver exposed group.
- Kidney function appeared to be adversely affected because of the exposure to cadmium.
Strengths and weaknesses:
- The small group of subjects limited the statistical power of the findings and precluded definite conclusions of rates of illness in the whole population.
- Limited information on actual environmental levels of silver exposure or air contaminats was obtained.

Applicant's summary and conclusion

Conclusions:
Exposure to silver compounds such as silver oxide and nitrate caused irritation of the eye, nose and throat in 15 out of 27 workers; nine had respiratory symptoms (cough, wheezing and chest tightnes) and eight complained of nose bleeds. Some individual with long-term exposure had conjunctival deposition and corneal opacities (63%), and were more likely to report problems with night vision.