Hazardous Chemical Information System (HCIS)

PCBs

Carcinogen Category first adopted in 1990

Carcinogen category notice: Category 2 . Probable human carcinogen for which there is sufficient evidence to provide a strong presumption that human exposure might result in the development of cancer . This evidence is generally based on appropriate long term animal studies, limited epidemiological evidence or other relevant information . See Chapter 13: Guidance Note on the Interpretation of Exposure Standards for Atmospheric Contaminants in the Occupational Environment, published by Worksafe Australia .

Skin absorption notice: Absorption through the skin may be a significant source of exposure . See Chapter 11 of the Guidance Note on the Interpretation of Exposure Standards for Atmospheric Contaminants in the Occupational Environment, published by Worksafe Australia .

Documentation notice: National Occupational Health and Safety Commission documentation available for these values.

No standard should be applied without reference to Guidance on the interpretation of Workplace exposure standards for airborne contaminants.

Carcinogen Category 2 (Probable Human Carcinogen)

Skin Absorption

Note: These exposure standards are adopted from the ACGIH TLVs list . Readers should refer to the ACGIH documentation of chlorodiphenyls ⁽¹⁾ for substantiation for these values . Moreover, after detailed review of the relevant literature, the Exposure Standards Working Group has recommended that PCBs be classified as Category 2 carcinogens . This documentation provides a summary of the carcinogenicity review and substantiates the Working Group's classification.

1. CARCINOGENICITY

1.1 Animal Studies

The International Agency for Research on Cancer ( IARC ) has reviewed ^{(2 ,3 )} the carcinogenicity of PCBs in experimental animals.

Ito et al ⁽⁴⁾ fed mice with Kanechlor 300 ( similar or equal to 30% chlorine), 400 ( similar or equal to 48% chlorine), or 500 ( similar or equal to 52% chlorine) for 32 weeks . Of 12 mice given 500mg/kg body weight Kanechlor 500, five developed hepatocellular carcinomas . No tumours occurred in other groups.

Kimbrough & Linder ⁽⁵⁾ found that mice fed daily with 49.8mg Aroclor 1254 (54% chlorine)/kg body weight for 11 months developed hepatomas.

Rats fed with Kanechlor 300, 400, or 500 developed hepatic nodular hyperplasia; the incidence increasing with degree of chlorination and with concentration of the PCBs in the diet ⁽⁶⁾ . In another study ⁽⁷⁾ , 26 out of 184 rats fed with Aroclor 1260 (60% chlorine) developed hepatocellular carcinomas.

1.2 Human Studies

Bahn et al ^{(8 ,9 )} reported two malignant melanomas from 31 workers heavily exposed to Aroclor 1254.

In a study ^{(10 ,11 )} of 2500 workers who were exposed to Aroclor 1254 in the manufacture of electrical capacitors, five liver deaths were observed, as compared to 1.9 expected.

Bertazzi et al ⁽¹²⁾ studied the cancer mortality of 2100 capacitor workers for the period 1946-82 . Exposure in the early years was to PCBs (54% chlorine) which were later replaced by mixtures containing 42% chlorine . The researchers found an increased cancer mortality in both male (14 observed, 7.6 expected) and female workers (12 observed, 5.3 expected).

Gustavsson ⁽¹³⁾ studied 142 male capacitor workers who were exposed to PCBs (up to 42% chlorine) in the period 1965-80 . The researchers observed no excess in cancer incidence.

After contamination of rice oil with Kanechlor 400 in Japan in 1968, a large population was intoxicated (' Yusho disease') ^(2,3) . This cooking oil was also contaminated with polychorinated dibenzofurans . A study of 887 male patients showed increased mortality from all cancers (33 observed, 15.5 expected), from liver cancer (9 observed, 1.6 expected) and from lung cancer (8 observed, 2.5 expected), which were statistically significant . However, a similar study of 874 female patients did not demonstrate this relationship ⁽¹⁴⁾.

2. CONCLUSION

Certain PCBs (particularly with more than 50% chlorine) produced benign and malignant liver neoplasms in mice and rats after oral administration . Carcinogenicity of PCBs through inhalation has not been demonstrated in animals.

There is limited evidence for carcinogenicity of PCBs in humans.

3. RECOMMENDATION FOR CARCINOGEN CATEGORY

After reviewing the relevant data, the Exposure Standards Working Group is of the view that there is sufficient evidence to provide a strong presumption that human exposure to PCBS may result in the development of cancer, based on animal studies and limited epidemiological evidence . The Working Group recommends that PCBs be classified as Category 2 Carcinogens (Probable Human Carcinogens) . The reader is encouraged to review the section on Carcinogens in the Guidance Note on the Interpretation of Exposure Standards for Atmospheric Contaminants in the Occupational Environment for guidance on the classification system of carcinogens.

REFERENCES

1. American Conference of Governmental Industrial Hygienists ( ACGIH ), Documentation of the threshold limit values and biological exposure indices, 5th edition, Cincinnati Ohio 1986

2. International Agency for Research on Cancer, IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans: Volume 18; IARC , Lyon , France , p.43-103, 1978

3. International Agency for Research on Cancer, IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, Suppl.7, IARC , Lyon, France, p.322-326, 1987

4. Ito N et al, "Histopathologic studies on liver tumorigenesis induced in mice by technical polychlorinated biphenyls and its promoting effect on liver tumors induced by benzene hexachloride ", J Natl Cancer Inst, 51, 1637-1646, 1973

5. Kimbrough RD & Linder RE, "Induction of adenofibrosis and hepatomas of the liver in BALB/cJ mice by polychlorinated biphenyls ( Aroclor 1254)", J Natl Cancer Inst, 53, 547-552, 1974

6. Ito N et al, "Histopathological studies on liver tumorigenesis in rats treated with polychlorinated biphenyls", Gann, 65, 545-549, 1974

7. Kimbrough RD et al, "Induction of liver tumors in Sherman strain female rats by polychlorinated biphenyl Aroclor 1260", J Natl Cancer Inst, 55, 1453-1459, 1975

8. Bahn AK et al, "Melanoma after exposure to PCB's", New Engl J Med, 295, p.450, 1976

9. Bahn AK et al, "PCB ? and melanoma", New Engl J Med, 296, p.108, 1977

10. Brown DP & Jones M, "Mortality and industrial hygiene study of workers exposed to polychlorinated biphenyls", Arch Environ Health, 36, 120-129, 1981

11. Brown DP, "Mortality of workers exposed to polychlorinated biphenyls . An update", Arch Environ Health (in press), 1987

12. Bertazzi PA et al, "Cancer mortality of capacitor manufacturing workers", Am J Ind Med, 11, 165-176, 1987

13. Gustavsson P et al, "Short-term mortality and cancer incidence in capacitor manufacturing workers exposed to polychlorinated biphenyls (PCBs)", Am J Ind Med 10, 341-344, 1986

14. Kuratsune M et al, "Analysis of deaths seen among patients with Yusho " (Abstract FL17), In: Dioxin 86, Proceedings of the VI International Symposium on Chlorinated Dioxins and Related Compounds, Fukuoka, Japan, 1986, p.179

Footnotes:
Documentation notice:

Entries carrying a notice for National Occupational Health and Safety Commission documentation indicate that these substances have been reviewed in detail by the Exposure Standards Expert Working Group and that documentation supporting the adopted national values is available in the National Commission's Documentation of the Exposure Standards [NOHSC:10003(1997)].