New Considerations for: New Considerations for: “If It’s Silica “If It’s Silica – It’s Not Just Dust” If Its Silica If Its Silica Its Not Just Dust It’s Not Just Dust” Its Not Just Dust Presented by: Donna M. Ringo, CIH DMR & Associates, Inc., Louisville, Kentucky
Honorable Mention Honorable Mention Honorable Mention Honorable Mention OSHA / NIOSH updates Disclaimer : I am not a toxicologist. The information presented here is the viewpoint of one industrial hygienist to the best of my Knowledge.
Power Generation Power Generation Power Generation Power Generation � Coal Dust � Fly Ash A
Navy Documents before WW II Navy Documents before WW II Navy Documents before WW II Navy Documents before WW II � Silicosis: major concern with ith shipbuilding � Asbestosis – few cases
Navy Documents before WWII Navy Documents before WWII Navy Documents before WWII Navy Documents before WWII � Silicosis: major concern with ith shipbuilding, pages 88- 116 pages 88 116 � Asbestosis – one short paragraph h
st Edition Patty’s 1 Patty’s 1 st Pattys 1 Pattys 1 Edition Edition - 1947 Edition 1947 1947 1947 � 27 pages silica � 6 pages asbestos 6
OSHA Table Z OSHA Table Z-3 OSHA Table Z OSHA Table Z 3
Silica, Silicosis, and Cancer Silica, Silicosis, and Cancer Silica, Silicosis, and Cancer Silica, Silicosis, and Cancer
Carcinogenicity Carcinogenicity Carcinogenicity Carcinogenicity 1997, the International Agency for Research on Cancer (IARC) reviewed the available C (IARC) i d th il bl animal and human studies and came to the conclusion that there was sufficient ff evidence in experimental a nimals for the carcinogenicity of inhaled silica, and there was sufficient evidence in humans d h ffi i id i h for the carcinogenicity of inhaled crystalline crystalline Silica Silica from from occupational occupational sources. [ACGIH].
Documentation of TLV’s Documentation of TLV’s Documentation of TLVs Documentation of TLVs
Documentation of TLV’s (cont ) Documentation of TLV’s (cont ) Documentation of TLVs (cont.) Documentation of TLVs (cont.) “The consensus among a number of g U.S. and international agencies is that a positive association exists between a positive association exists between silica exposures and lung cancer, but not all have decided that silica is a t ll h d id d th t ili i confirmed human carcinogen. “ ….. (and) ( )
Documentation of TLV’s (cont ) Documentation of TLV’s (cont ) Documentation of TLVs (cont.) Documentation of TLVs (cont.) “There is little support for the hypothesis pp yp that occupational silica exposure is a direct-acting initiator, while at the same g time, there is compelling evidence that many forms of pulmonary fibrosis y p y constitute major risks for human lung cancer. Available data do not prove that p the fibrosis associated with silicosis leads directly to lung cancer among silica- y g g exposed workers. “
Crystalline SiO Crystalline SiO 2 Factors Crystalline SiO Crystalline SiO 2 Factors Factors Factors � Particle size P ti l i ◦ < 10 microns respirable � Freshly Cleaved Edges ◦ Enzyme stimulated ◦ Enzyme stimulated � Quartz vs Cristobalite Quartz vs Cristobalite � Exposure and Latency Period p y
Basics of Dusty Lung Diseases Basics of Dusty Lung Diseases Basics of Dusty Lung Diseases Basics of Dusty Lung Diseases � Effect of dusts/particulates ◦ Body’s natural defenses � Nasal hairs � Upper respiratory curve U i � Mucocilliary escalator
Basics of Dusty Lung Diseases Basics of Dusty Lung Diseases Basics of Dusty Lung Diseases Basics of Dusty Lung Diseases ◦ Air sacs or alveoli
Body Response(s) Body Response(s) Body Response(s) Body Response(s) ◦ Cellular actions � Macrophage attempts but fails � Macrophage succeeds then ruptures � Local inflammation L l i fl ti � Scaring occurs
Fibrotic nodules Fibrotic nodules Fibrotic nodules Fibrotic nodules � Scar tissue build-up
Fibrosis Fibrosis Fibrosis Fibrosis � Scar tissue linking
Lung Damage Results Lung Damage Results Lung Damage Results Lung Damage Results � Scar Tissue – reduces O 2 -CO 2 exchange S O CO � Fibrosis – Progressive and usually Fib i P i d ll non/reversible � Debilitating Silicosis loss of elasticity � Debilitating Silicosis – loss of elasticity � Stages: Category 1 through 4 � Stages: Category 1 through 4
Symptoms Symptoms Symptoms Symptoms � Shortness of Breath Sh f B h � Fatigue � Coughing � Coughing � Wheezing � Chest Pain � Chest Pain From the loss of gas exchange and the loss of elasticity of the lung f y f g
Inflamation Inflamation Inflamation/Fibrosis Inflamation/Fibrosis /Fibrosis /Fibrosis Silica Silicosis Asbestos Asbestosis Iron oxide Iron oxide Siderosis Siderosis Cotton dust Bysinosis Beryllium Berylliosis Pumice Pumice Pseudopneumovolcanoconiosis Pseudopneumovolcanoconiosis
How much dust does it take? How much dust does it take? How much dust does it take? How much dust does it take?
How much dust does it take? How much dust does it take? How much dust does it take? How much dust does it take? � Cumulative dose information ◦ A cumulative exposure of <2,000 ug/m3-year did not result in an increase in silicosis prevalence in either smokers or nonsmokers prevalence in either smokers or nonsmokers. ◦ Cumulative exposures in the range of 2000 to Cumulative exposures in the range of 2000 to 3000 ug/m3-year resulted in a prevalence of 0.9 in nonsmokers and 1.8 in smokers. (54) 54. Cherry MN; Burgess GL; Turner S; McDonnald JC:.Crystalline silica and risk of lung cancer in � the potteries. Occup Inviron Med. 55:779–785 (1998).
Cumulative dose as threshold for Cumulative dose as threshold for minimum risk of disease development: minimum risk of disease development: p Smoking and Lung Cancer 10 pack year history : increased risk 10 years of 1 pack per day or 5 years of 2 packs/day *Ri k i *Risk increases with increased pack years i h i d k
Cumulative dose as threshold for Cumulative dose as threshold for minimum risk of disease development: minimum risk of disease development: p Asbestos and Mesothelioma 5 fiber-year history : increased risk 1 years at 5 f/cc daily exposure, or 5 years at 1 f/cc daily exposure or 5 years at 1 f/cc daily exposure, or 50 yrs at 0.1 f/cc daily exposure
Cumulative dose as threshold for Cumulative dose as threshold for minimum risk of disease development: minimum risk of disease development: p Silica and Silicosis Silica and Silicosis < 2,000 ug/m 3 -year : No increased risk , g y = 2 mg/m 3 -years 20 yrs @ 0.1 mg/m 3 daily exposure = = 40 yrs @ 0.05 mg/m 3 daily exposure Numerous research publications have higher and lower cumulative d doses reported. d
Cumulative dose as threshold for Cumulative dose as threshold for minimum risk of disease development: minimum risk of disease development: p Using New Threshhold Limit Value - 0.025 mg/m 3 for a working lifetime 3 f 0 025 / ki lif ti (40 yrs) => 1 mg.m 3 -yr cum. dose Dose should prevent silicosis Dose should prevent silicosis – – and and therefore prevent any risk of lung therefore prevent any risk of lung therefore prevent any risk of lung therefore prevent any risk of lung cancer from crystalline silica. cancer from crystalline silica.
Lung disease Book Lung disease Book Lung disease Book Lung disease Book
Mesothelioma Mesothelioma –NIOSH/CDC Mesothelioma Mesothelioma NIOSH/CDC NIOSH/CDC NIOSH/CDC
Silicosis Silicosis – NIOSH/CDC Silicosis Silicosis NIOSH/CDC NIOSH/CDC NIOSH/CDC
Prevention of Silicosis Prevention of Silicosis Prevention of Silicosis Prevention of Silicosis � Ventilation � Isolation � Dust Suppression � Substitution � Respiratory Protection Protection
Litigation/Expert Witness Litigation/Expert Witness Litigation/Expert Witness Litigation/Expert Witness
Questions and Answers Questions and Answers Questions and Answers Questions and Answers
Silica 3D Silica 3D Silica 3D Silica 3D
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