Thursday, 6 October 2011

The unholy trio of the sandpit - Toxoplasmosis, Meliodosis and Silicosis Pt 3




Part 3 - Silicosis
Summary 
1) Sand is a naturally occurring granular material composed of finely divided rock and mineral particles. The composition of sand is highly variable, depending on the local rock sources and conditions but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica .The composition of sand is highly variable, depending on the local rock sources and conditions...’ 

2) Silicosis is a form of occupational lung disease caused by inhalation of crystalline silica dust. While crystalline silica is a known human carcinogen, the amount of exposure is a factor.

3) During the 1980’s studies by the International Agency for Research on Cancer (IARC) determined that continued exposure to certain concentrations of crystalline silica dust over extended periods without the use of PPE or work safety practices caused it to act as a carcinogen. The silica was usually fine dust specially formulated for industries (i.e. sand blasting, glass foundries etc.), or was a component of bulk lots used in other industries.

4) Rather than assess each of the 650,000 produces containing crystalline silica dust the US Occupational Safety and Health Administration (OSHA) released a generic Hazard Communication Standard (HCS). Under the HCS, OSHA regulated that businesses that use materials containing 0.1% or more crystalline silica must follow Federal guidelines concerning hazard communication. Specifically, HCS has the following requirements: Chemical manufacturers and importers—must determine the hazards of their products.

5) In 1986 the State of California passed Proposition 65. Like the OSHA’s HCS, Proposition 65 put the burden of proof on business instead of government to make a key scientific determination about safety levels for specific chemicals. Under Prop. 65 any product that may contain any substance may be hazardous has to be labelled with the generic warning “WARNING: This product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.[i]

6) Because of the OSHA & OEHHA’s onus on suppliers and distributers providing proof of their product being safe most simply choose to supply the generic warning[ii] [iii] if their product contains any of the chemicals contained in the OEHHA’s list[iv].

7) There are a number of sand types available to consumers to use in sand play pits/boxes. “Safe” play sand suppliers suggest that their sand (beach or river sand) is better for childrens play as it has been washed, screened and graded They state that most bagged sand is obtained from crushed quarry quartz which, may/may not also contain tremolite. Some scientists believe tremolite particles can cause cancer like other forms of asbestos to which humans are exposed.

8) There are very few long term studies that can provide a definitive answer as to whether children playing in sand may be exposed to carcinogenic substances (with so many variables i.e., what types of sand is it, were was it obtained, what is its composition, what are the concentrations of its components, what type of environment is the sand pit box in, how long is the child at play, etc.) One researcher, Dr. Michael Babich, a scientist at the Consumer Product Safety Commission who worked on a study that looked specifically at play sand and children's exposure to it suggests, ‘Researchers would have to follow children for a lifetime, and even then couldn't distinguish cancers from a crystalline silica exposure and those from other environmental exposures, like pollution.’

9) Simple safety protocols for sand play would be: 
· Make sure that the sandboxes children come in contact with in all early childhood settings are outdoors. 
· Keep sandboxes damp (not necessarily wet), to keep any dust down. This step is especially important in arid climates. 
· Be aware as to the source of the play sand you intend to use. Do not use bagged play sand that has been derived from crushed quarry quartz. Purchase River or Beach sand that has been washed and screened/graded. 
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Silicosis, also known as Potter's rot, is a form of occupational lung disease caused by inhalation of crystalline silica dust, and is marked by inflammation and scarring in forms of nodular lesions in the upper lobes of the lungs. Silica occurs in 3 forms: crystalline, microcrystalline (or cryptocrystalline) and amorphous (non-crystalline). 

Silicosis is due to deposition of fine respirable dust (less than 10 micrometers in diameter) containing crystalline silicon dioxide. While crystalline silica is a known human carcinogen, the amount of exposure is a factor. Chronic simple silicosis usually results from long-term exposure, 10 years or more, to high concentrations of respirable silica dust. Accelerated silicosis usually occurs after 5–10 years of exposure to higher concentrations of silica dust. Acute silicosis is known to develop after few weeks to 5 years of exposure to high concentrations of respirable silica dust. 
[v] 

During the 1980’s studies were performed by the International Agency for Research on Cancer (IARC) in industries where workers were continually exposed to high concentrations of respirable crystalline silica (i.e. stone masons, quarrymen, miners, sandblasters, ceramicists, potters, foundry workers, grinders, stone cutters, brick workers etc.) The studies determined that crystalline silica was a carcinogen. As a result of these findings, crystalline silica was regulated under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS). Under the HCS, OSHA regulated that businesses that use materials containing 0.1% or more crystalline silica must follow Federal guidelines concerning hazard communication. 

In the development of the HCS, OSHA realized that the task before it was herculean: to evaluate all the substances to which workers are exposed, as many as 650,000 of which were potentially hazardous. The Agency decided to adopt a generic approach, and promulgated the HCS, which requires container labelling, material safety data sheets, and training. Specifically, HCS has the following requirements: Chemical manufacturers and importers—must determine the hazards of the product. Suppliers are held responsible for determining whether a substance is covered, including whether the quantity of the hazardous chemical in a mixture exceeds these cut-offs. Testing is not required; the employer may assume that if the hazardous chemical is present, the mixture is covered.”
 [vi] 

In 1986 the State of California passed Proposition 65 (formally titled "The Safe Drinking Water and Toxic Enforcement Act of 1986. Its goals were to protect drinking water sources from toxic substances that cause cancer and birth defects and to reduce or eliminate exposures to those chemicals generally by requiring warnings in advance of those exposures. Like the OSHA’s HCS, Proposition 65 put the burden of proof on business instead of government to make a key scientific determination about safety levels for specific chemicals. 

In addition because the law allowed private citizens to sue and collect damages from any business violating the legislation there have been cases of lawyers and law firms using Proposition 65 to force monetary settlements out of California businesses
.[vii] The Californian Attorney General's office has cited several instances of settlements where plaintiff attorneys received significant awards without providing any environmental benefit. 

Under Prop. 65 any product that may contain any substance that may be hazardous has to be labelled with the generic warning “WARNING: This product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.”[viii] 

Because of the OSHA &the OEHHA’s (Office of Environmental Health Hazard Assessment) onus on suppliers and distributers providing proof of their product being safe, most simply chose to supply the generic warning
[ix] [x]if their product contains any of the chemicals contained in the OEHHA’s list.[xi] 

The OEHHA’s own website recognises in its FAQ’s that the warning may mean something or... ..nothing. 

“Q: I recently bought a product that came with a Proposition 65 warning. How do I find out more about the warning and the chemicals in the product? 

A: Businesses are not required to provide OEHHA with any information regarding their Proposition 65 warnings. ....A business is not required to notify our office or any other regulatory agency when it decides to provide a warning. 

Q: Is a product safe if it carries a Proposition 65 warning? 

A: The fact that a product bears a Proposition 65 warning does not mean by itself that the product is unsafe. You could think of Proposition 65 more as a “right to know” law than a pure product safety law. 

Q. What is the acceptable concentration in my product for chemicals listed under Proposition 65? 

A. Under Proposition 65, there are no acceptable concentrations established for any listed chemical in any given product. An exposure that causes a significant risk of harm from a listed chemical through the use of a product would trigger the warning requirement, not merely the fact that a listed chemical is present in a product. The concentration of a listed chemical would certainly factor into the level of exposure that would result from an individual using a given product. But concentration alone is not sufficient to determine if warnings are required. 

Nola Enge a doctoral student at the Arizona State University in her article Is your child's sandbox a safe place to play? provides information derived from Dr. Michael Babich, a scientist at the Consumer Product Safety Commission (CPSC). ’I turned to Dr. Michael Babich, a scientist at the Consumer Product Safety Commission who worked on the one study I found that looked specifically at play sand and children's exposure to it (CPSC, 2004, p. 71). While this study has not reached any definitive conclusions yet, he was able to help me understand the following: 

The science is not well understood with regard to childhood exposure because there is no way to get the answers. Researchers would have to follow children for a lifetime, and even then couldn't distinguish cancers from a crystalline silica exposure and those from other environmental exposures, like pollution. 
It is much easier to show a connection between cancer and workers in high-risk occupations. They are exposed to higher levels for longer periods of time than children are in the sandbox. 

The CPSC study measured many different brands of play sand and found most of their samples were between 90-100 percent pure crystalline silica. Although children are exposed to crystalline silica in the sandbox, we just don't know at what levels or how it affects them. Babich said that we do know the risk to children is, at worst, much lower than it is for workers. Children are exposed at lower levels and intermittently’ (M. Babich, personal communication, August 26, 2005). 

Enge suggests that a prudent safety protocol would be to: 

· Make sure that the sandboxes children come in contact with in all early childhood settings are outdoors. 
· Keep sandboxes damp (not necessarily wet), to keep the dust down. This step is especially important in arid climates. 
· Purchase play sand, not all-purpose sand. Generally, play sand is grainier because it has been washed and screened, so the really fine dust is washed away. 

A fairly absolute clarification of the topic can be found in the attached personal correspondence from Dr Philip J. Landrigan, MD, MSc, Professor of Pediatrics, Director, Children's Environmental Health Center, Mount Sinai School of Medicine. New York, 4th September 2011. 

“Dear Mr Reed 

Thank you for your email. 

Silicosis is not a risk for children in sand boxes. Silicosis is an industrial lung disease of workers who are occupationally exposed for many years to very high levels of airborne silica such as sandblasters and quarry workers. There is no way that children, even with their delicate lungs and airways, can attain levels of exposure in a sandbox that are anywhere close to those required to induce silicosis. 

With regard to exposure to asbestos-like minerals in play sand, the situation is very different. The issue is that some play sand is not beach sand (which is what I had always imagined), but instead is produced by crushing quarried rock that has been mined in quarries where the native rock contains asbestos. When this rock is crushed to make play sand, the asbestos – which is a fibrous mineral - is released. These asbestos fibers are microscopic in size and can be inhaled by children if the sand is tossed into the air during play or lifted by the wind. I can attest that these fibers are present in some samples of commercially purchased play sand, because I have seen images of these fibers that my team took through the electron microscope. 

Unlike silica, even very small exposures to inhaled airborne asbestos are dangerous for children because the inhaled asbestos fibers can lodge in the lung tissue where they are virtually indestructible, cause chronic irritation/inflammation of the lining of the lungs, the pleura, and decades later cause a cancer named human malignant mesothelioma, a very nasty tumor, almost universally fatal, that typically kills within one year of diagnosis. 
This was the basis for my statement that "If children inhale these fibers they are at risk of getting lung cancer later,'' he said. ''Either this play sand should be banned or labeled with a skull and crossbones.'' ' 

Hope this helps 

Philip J. Landrigan, MD, MSc 

Dean for Global Health 
Ethel H. Wise Professor and Chairman 
Department of Preventive Medicine 
Professor of Pediatrics 
Director, Children's Environmental Health Center 
Mount Sinai School of Medicine 
17 East 102nd Street, Room D3-145 
New York, NY 10029-6574 
WHO Collaborating Centre in Children’s Environmental Health 

[i] http://oehha.ca.gov/prop65.html 
[ii] http://www.prop65news.com/pubs/brochure/madesimple.html 
[iii] http://en.wikipedia.org/wiki/California_Proposition_65_(1986)#cite_note-House-13 
[iv] http://www.oehha.ca.gov/prop65/prop65_list/files/P65single072911.pdf 
[v] http://en.wikipedia.org/wiki/Silicosis 
[vi] Crystalline Silica Primer, US Dept of the Interior and US Bureau of Mines, 1992 
[vii] http://ag.ca.gov/newsalerts/release.php?id=1207 
[viii] http://oehha.ca.gov/prop65.html 
[ix] http://www.prop65news.com/pubs/brochure/madesimple.html 
[x] http://en.wikipedia.org/wiki/California_Proposition_65_(1986)#cite_note-House-13 
[xi] http://www.oehha.ca.gov/prop65/prop65_list/files/P65single072911.pdf

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