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Type of information:
experimental study
Adequacy of study:
other information
2 (reliable with restrictions)

Data source

Reference Type:
Human eyposure to heavy metals. Rare earth pneumoconiosis in occupational workers
G. Vocaturo, F. Colombo, F. Rodi, E. Sabbioni, R. Pietra
Bibliographic source:
Chest 1983; 780-783

Materials and methods

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:


Type of population:
Details on study design:
Study population:
The examined patient was a 58-year-old man, a light smoker, who worked for 46 years in a photoengraving laboratory in which he was exposed to smoke emitted from carbon arc lamps. He was admitted to the Hospital of Cuasso al Monte, Varese, Italy.

Clinical test:
Cyanosis of the extremities and crepitant rales and also retriculonodular alterations in both lungs, with increase in the cardiac transverse diameter were noted. An ECG showed hypertrophy and overloading of the right ventricle. Cardiac catheterization on the right side showed pulmonary hypertension with increased vascular resistance.

Control group:
Specimens of lung and lymph node biopsies were taken from the photoengraver at the Cuasso al Monte Hospital. Lung and lymph node samples as controls were chosen from autopsies of 11 subjects not professionally exposed and living in the same district of North Italy.

Results and discussion

The results indicate an excessice, abnormal concentration of RE in the lungs and in the lymph nodes of the workers, suggesting a relationshop between the diagnosed pneumoconiosis and occupational exposure to RE.

La, Ce, Nd, and Sm were considerably higher in the lungs of the workers in comparison to the corresponding RE pulmonary levels of the control subjects (see table)
La, Ce, Nd and Sm were significantly higher than the corresponding mean values found in the lymph nodes of the control group (see table)

Any other information on results incl. tables

Concentrations of RE and Thorium in Lung Tissues of the Examined Worker and Control Subjects

Concentration, ppb (ng/g wet tissue)

Element              Worker              Controls              Ratio, Worker/control

Ce                     166500              70.6(11)              2358

Nd                     57750               46.2(6)               1250                     

La                      45600               16.6(11)              2747

Sm                      4550               2.5(10)               1820                     

Yb                          252               3.5(9)                     72

Tb                          230               1.7(7)                    131

Eu                            87,5              1.2(11)                  73

Lu                            25                  0.4(9)                   58

Th                          175                  7.3(7)                    24

Concentrations of RE and Thorium in Lymph Nodes of the Examined Worker and Control Subjects

Concentration, ppb (ng/g wet tissue)

Element              Worker              Controls              Ratio, Worker/control

Ce                     4903              93(8)                            53

Nd                     2375               118(7)                        20                    

La                      2310               28(3)                      82

Sm                      321               3.7(2)                           87                     

Yb                        4.8               4.4(11)                         1

Tb                         3.1               9.7(3)                           0.3

Eu                         1.6               0.7(3)                          2.3

Lu                         0,5                 1.3(5)                        0.4

Th                       28.6                24.5(4)                       1.5

The tables give the concentration of eight RE and Th expressed as ng/g of wet tissue, in the lung and prescalenic lymph nodes of the photoengraver as well as in the corresponding tissues of the control group.

Applicant's summary and conclusion

RE is used in the manufacture of optical glass and in ceramic glasses as an abrasive; for the preparation of special alloys and deoxidizer agents, as arc-stabilizer in cored carbon arc lamps, in the gas-mantle industry and in various pyrotechnics. Other uses include control rods in nuclear reactors; in the electronics industry, such as in color television tubes; for mercury vapor and fluorescent lamps.
Some metals are industrial hazards and their inhalation plays an important role in determining pulmonary histopathologic alterations.
Long-term exposure of occupational workers to RE dusts can induce bronchiolar alveolar, and interstitial histologic reactions in the lung, observed in the case presented here.

The present case showed a clearly abnormal presence of RE in lung and lymph nodes of the worker examined. RE as irritative agents causing long-term morphologic changes in the lung with fibrosis of the interstitial tissue and bronchitis of the respiratory tract. The levels of RE in the blood and urine of the worker were extremely low.
Executive summary:

A male subject exposed for many years to rare earth (RE)- containing fumes and dusts emitted from carbon arc lamps in photoengraving laboratories was investigated to rule out RE pneumoconiosis. Chest x-ray films showed a severe pulmonary fibrosis and high RE concentrations in the pulmonary and lymph node. The long-term accumulation of RE in the lungs played a role in the pathogenesis of the observed pulmonary fibrosis of the worker.