New Considerations for: New Considerations for: If Its Silica If - - PowerPoint PPT Presentation

New Considerations for: New Considerations for: “If It’s Silica “If It’s Silica – It’s Not Just Dust” It’s Not Just Dust” If Its Silica If Its Silica Its 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

A

Fly Ash

Navy Documents before WW II Navy Documents before WW II Navy Documents before WW II Navy Documents before WW II

Silicosis: major

ith concern with shipbuilding

Asbestosis –

few cases

Navy Documents before WWII Navy Documents before WWII Navy Documents before WWII Navy Documents before WWII

Silicosis: major

ith concern with shipbuilding, pages 88- 116 pages 88 116

Asbestosis –

• ne short

h paragraph

Patty’s 1 Patty’s 1st

st Edition

Edition - 1947 1947 Pattys 1 Pattys 1 Edition Edition 1947 1947

27 pages silica

6

6 pages asbestos

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 C (IARC) i d th il bl

• n Cancer (IARC) reviewed the available

animal and human studies and came to the conclusion that there was sufficient ff evidence in experimental animals for the carcinogenicity of inhaled silica, d h ffi i id i h and there was sufficient evidence in humans for the carcinogenicity

• f

inhaled crystalline Silica from

• ccupational

crystalline Silica from

• ccupational
• 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 t ll h d id d th t ili i not all have decided that silica is a 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 SiO2 Factors Factors Crystalline SiO Crystalline SiO2 Factors Factors

P ti l i

Particle size

• < 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 U i Upper respiratory curve 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 L l i fl ti Local inflammation 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

S O CO

Scar Tissue – reduces O2-CO2 exchange

Fib i P i d ll

Fibrosis – Progressive and usually

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

Sh f B h

Shortness of Breath 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/Fibrosis /Fibrosis Inflamation Inflamation/Fibrosis /Fibrosis

Silica Silicosis Asbestos Asbestosis Iron oxide Siderosis Iron oxide Siderosis Cotton dust Bysinosis Beryllium Berylliosis Pumice Pseudopneumovolcanoconiosis Pumice 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 i h i d k *Risk increases with increased pack years

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/m3-year : No increased risk , g y = 2 mg/m3-years

= 20 yrs @ 0.1 mg/m3 daily exposure = 40 yrs @ 0.05 mg/m3 daily exposure

Numerous research publications have higher and lower cumulative d d doses reported.

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 /

3 f

ki lif ti 0.025 mg/m3 for a working lifetime (40 yrs) => 1 mg.m3-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 NIOSH/CDC Mesothelioma Mesothelioma NIOSH/CDC NIOSH/CDC

Silicosis Silicosis – NIOSH/CDC NIOSH/CDC Silicosis Silicosis 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