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Registry of Toxic Effects of Chemical Substances (RTECS)

Silica, crystalline - tridymite

RTECS #

VV7335000

CAS #

15468-32-3; 1317-94-8; 12414-70-9

Updated

July 2013

Molecular Weight

60.09

Molecular Formula

O2Si

Synonyms

alpha-Tridymite
Christensenite
Silica, crystalline-tridymite (ACGIH:OSHA)
Tridimite (French)
Tridymite
Tridymite 118

Mutation Data and Reference

System TestRoute/Organism/TissueDoseReference
sister chromatid exchangelymphocyte/human13514 µg/kgBJIMAG 47,110,1990

Tumorigenic Data and References

Route/OrganismDoseEffectReference
intrapleural/rat lowest published toxic dose: 100 mg/kgTumorigenic: Equivocal tumorigenic agent by RTECS criteria

Blood: Lymphoma including Hodgkin's disease		BJCAAI 41,908,1980
intratracheal/mouse lowest published toxic dose: 400 mg/kgTumorigenic: Equivocal tumorigenic agent by RTECS criteria

Lung, Thorax, or Respiration: Tumors		PAACA3 15,6,1974

Acute Toxicity Data and References

Route/OrganismDoseEffectReference
inhalation/human lowest published toxic concentration: 16 million particles per cubic foot/8H/17.9Y- intermittentLung, Thorax, or Respiration: Fibrosis, focal (pneumoconiosis)

Lung, Thorax, or Respiration: Cough

Lung, Thorax, or Respiration: Dyspnea		NTIS** PB246-697
intratracheal/rat lowest published lethal dose: 200 mg/kgLung, Thorax, or Respiration: Fibrosis, focal (pneumoconiosis)BJIMAG 10,9,1953

Reviews

OrganizationStandardReference
International Agency for Research on Cancer (IARC)Cancer Review:Animal Sufficient EvidenceIMEMDT 42,39,1987
International Agency for Research on Cancer (IARC)Cancer Review:Human Limited EvidenceIMEMDT 42,39,1987
International Agency for Research on Cancer (IARC)Cancer Review:Animal Limited EvidenceIMEMDT 68,41,1997
International Agency for Research on Cancer (IARC)Cancer Review:Group 2AIMSUDL 7,341,1987

Standards and Regulations

OrganizationStandardReference
Mine Safety and Health Administration (MSHA) STANDARD-respirable dust in airtime-weighted average 10 mg/m3/2(% resp. SiO2+2)DTLWS* 3,33,1973
Mine Safety and Health Administration (MSHA) STANDARD-total dust in airtime-weighted average 30 mg/m3/2(% resp. SiO2+3)DTLWS* 3,33,1973
Occupational Exposure Limit IN ARGENTINA, BULGARIA, COLOMBIA, JORDAN check ACGIH TLV;
Occupational Exposure Limit IN SINGAPORE, VIETNAM check ACGIH TLV
Occupational Exposure Limit-AUSTRALIAtime-weighted average 0.1 mg/m3, JUL2008
Occupational Exposure Limit-BELGIUMtime-weighted average 0.05 mg/m3 (resp. dust), MAR2002
Occupational Exposure Limit-DENMARKtime-weighted average 0.05 mg/m3 (respirable), carc, MAY2011
Occupational Exposure Limit-DENMARKtime-weighted average 0.15 mg/m3 (total), MAY2011
Occupational Exposure Limit-FRANCEVME 0.05 mg/m3, (resp), FEB2006
Occupational Exposure Limit-ICELANDtime-weighted average 0.05 mg/m3 (resp. dust), NOV2011
Occupational Exposure Limit-KOREAtime-weighted average 0.05 mg/m3, 2006
Occupational Exposure Limit-MEXICOtime-weighted average 0.05 mg/m3 (respirable), 2004
Occupational Exposure Limit-NEW ZEALANDtime-weighted average 0.1 mg/m3 (respirable dust), JAN2002
Occupational Exposure Limit-NORWAYtime-weighted average 0.05 mg/m3 (resp. dust), JAN1999
Occupational Exposure Limit-NORWAYtime-weighted average 0.15 mg/m3 (total dust), JAN1999
Occupational Exposure Limit-PERUtime-weighted average 0,05 mg/m3, JUL2005
Occupational Exposure Limit-SWITZERLANDMAK-week 0.15 mg/m3, carc 1, resp, JAN2011
Occupational Exposure Limit-THAILANDtime-weighted average 10 mg/m3, JAN1993
Occupational Exposure Limit-THE NETHERLANDSMAC-TGG 0.075 mg/m3, 2003
Occupational Exposure Limit-UNITED KINGDOMtime-weighted average 0.1 mg/m3 (resp. dust), OCT2007
Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (Construction)8H time-weighted average 5 mg/m3/(% resp SiO2+2)CFRGBR 29,1926.55,1994
Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (General Industry)8H time-weighted average 5 mg/m3/(% resp SiO2+2)CFRGBR 29,1910.1000,1994

NIOSH Documentation and Surveillance

OrganizationStandardReference
National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Level TO SILICA, crystalline tridymite-air10H Carcinogen time-weighted average 0.05 mg/m3NIOSH* DHHS #92-100,1992
National Occupational Exposure Survey 1983Hazard Code 74617; Number of Industries 1; Total Number of Facilities 21; Number of Occupations 1; Total Number of Employees Exposed 2042; Total Number of Female Employees Exposed 351

Status in Federal Agencies

OrganizationReference
NIOSH Analytical Method, 1994: Silica, crystalline, by XRD, 7500; by VIS, 7600; by IR, 7602
NTP 11th Report on Carcinogens,2004:Known to be human carcinogen
OSHA ANALYTICAL METHOD #ID-125G

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