Friday, April 27, 2012

Workers Memorial Day

Tomorrow, April 28th is Workers Memorial Day, a day when we remember those people who died from injuries in the workplace. Secretary of Labor Hilda L. Solis issued a statement saying "Tomorrow, April 28, is Workers' Memorial Day, an occasion for reflection and remembrance of the thousands of workers who needlessly have suffered fatal injuries on the job every year. We also think of those workers who have been seriously injured or sickened as a result of preventable workplace hazards. "We are never prepared to say goodbye to the people we love, but we are even less so when we send our loved ones off for a day's work. It is our duty to ensure that all workers come home safely at the end of each workday, and we stand behind our firm conviction that workplace injuries and fatalities are entirely preventable. "On this day, I urge all Americans to raise their voices in support of workers' right to a safe and healthful workplace. In the 41 years since the Occupational Safety and Health Act was enacted, we have made tremendous progress, but our steadfast mission to make every job in America a safe job must continue. One workplace death is too many. Making a living shouldn't include dying.". And as the Secretary has said previously "With every one of these fatalities, the lives of a worker's family members were shattered and forever changed. We can't forget that fact." These statistics report tragic accidents that occur suddenly and with immediate impact, however many workplace injuries, such as those that result from chemical exposure may not produce symptoms for many years and so are not counted in the work place safety statistics. We know that many chemicals used in the workplace are carcinogenic and for a select few, OSHA has promulgated 27 legally binding standards covering nearly 40 carcinogens. However, there are hundreds of known human carcinogens according to International Agency for Research on Cancer and the National Toxicology Program. These organizations also name a much larger number of compounds that are suspected carcinogens. The American Cancer Society has them in a convenient list. This list is conservative and only includes those compounds shown to cause cancer or with incriminating evidence against them. The actual number of cancer causing compounds is certainly much higher. Cancer is one of the major causes of death in the US. In 2010, according to the CDC it was the second leading cause of death behind heart disease with 567,628 out of 2,437,163 deaths. and in 2012 the American Cancer Society estimates there will be 1,638,910 new cases of cancer. In pre-industrial cultures, while cancers did occasionally occur, they were very rare, indicating that cancers are largely caused by environmental factors; see for example Cancer As an Environmental Disease, By P. Nicolopoulou-Stamati, 2004 There are many different types of cancer and for those interested, the probability of a man or woman dying from a particular type of cancer has been tabulated. While exposure to cancer causing agents occurs in many aspects of life from smoking to exposure to benzene in gasoline, workplace exposures are considered to be at higher levels than for public exposures. We know that we are all exposed to many cancer causing agents, especially in the workplace, that many people will develop cancer from reasons unknown and that a large proportion of them will die of it. However, it is very rare that somebody with a cancer diagnose can be associated with exposure to a particular chemical. We don’t know what proportion of the over half million people who will die from cancer this year will do so because of workplace exposure, but it is likely that this number of hidden workplace fatalities far exceeds the 4,690 fatal workplace accidents (2010) that we are remembering tomorrow.

Thursday, April 19, 2012

Global harmonization Standards and the EPA

Recently OSHA provided a final rule for how it was going to change its hazard Communication standard 29 CFR 1910.1200 to reflect the global harmonization on chemical hazards (see earlier discussions of this topic in this blog).

The EPA operates under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and has its own regulations for describing chemical hazards on a safety data sheet. As a first step towards harmonization, on April 20th the EPA will publish a notice of the differences between its requirements for safety data sheets and OSHA's in the Federal Register.

We all know that regulations change at a glacial pace, and while this notice is not actually harmonization, hopefully this is the first small step in the right direction.

The ChemDAQ blog will continue to follow this story.

Thursday, April 12, 2012

Environmentally Friendly… to Whom?

ChemDAQ’s own Richard Warburton* recently had a paper published in Infection Control Today, the January 13th, 2012 edition. In this article, Richard points out that many people consider chemicals that are safe for the environment are obviously safe for general use. While this may be true for many compounds such as sugar which is generally benign except to our waistlines, Richard argues that an environmentally toxic chemical is one that is persistent in the environment (think DDT or mercury).

In contrast a chemical which is highly reactive is hazardous because of this reactivity but it is environmentally benign because it reacts so quickly that it disappears quickly. He gives the example of pouring either a solution of a cadmium salt or 30% hydrogen peroxide on to the ground. The hydrogen peroxide will fizz and froth and be gone in a few hours, but the cadmium may still be at detectable levels twenty years later in nearby water wells.

The take-home message is not to say that persistent chemicals cannot be harmful; some definitely are, but rather to illustrate that because a chemical product is labeled ‘green’ or ‘environmentally safe’ it doesn’t mean it is necessarily safe for those exposed to it.

* P. Richard Warburton, PhD, JD, is Chief Technology Officer and General Counsel at ChemDAQ Inc.

Wednesday, April 11, 2012

ChemDAQ Provides a Free Gas Concentration Converter

Gas concentrations are usually expressed in terms of parts per million, or mg/m3. Being able to convert from one unit to another is important since some regulations, industrial hygienists etc. prefer one format over the other. However, converting from one to other is not as simple as converting temperature from degrees Fahrenheit to degrees centigrade because ppm and mg/m3 are not strictly the same thing, mg/m3 is an actual concentration whereas ppm is a relative concentration.

If all this unit conversion sounds difficult, it need not be. ChemDAQ has produced a free unit conversion spreadsheet tool, available for download from the ChemDAQ website (at the bottom of the page). This tool allows simple conversion from ppm to mg/m3 and back again and even provides the molecular weights for many common gases and vapors found in healthcare. If we have missed any compounds that would be useful, please let us know and we will add them to the list.

A more detailed explanation of the difference between ppm and mg/m3 is provided below for those who are interested.

More Detailed Explanation
A concentration is defined as the amount of something per unit volume, so if the amount of a gas is expressed by its weight in mg, then the amount of gas per cubic meter (mg/m3) is the concentration. For a given gas concentration, the mass of gas per unit volume will be proportional to the molecular weight. Thus 1 liter of air has a mass (weighs) about 1.1 g, but 1 liter of 100% chlorine would weigh about 2.8g. The concentration unit of mg/m3 is the mass of the gas per cubic meter.

A part per million, as the name implies, is a relative concentration. If ethylene oxide - air mixture contains 1 ppm ethylene oxide, then for every million air molecules there is one ethylene oxide molecule. Parts per million are particularly useful when dealing with compressed gases, which may be why we use it in gas detection so much. A 2000 psi compressed gas cylinder of 10 ppm ethylene oxide has a much higher internal concentration in terms of mg/m3 than the test gas coming out of the regulator at 1 psi, but the relative concentration of EtO to air, i.e. 10 ppm is the same.

Therefore the relative amount of gas (in ppm) must be multiplied by the molecular weight, as well as changing the units to calculate the weight. In addition to adjusting the units, to convert from ppm to mg/m3, it is necessary to specify a temperature (usually 25 oC) and a pressure (usually 1 atm.).

If the conversion of gas concentrations from ppm to mg/m3 or vice versa sounds involved, use the ChemDAQ gas concentration conversion tool, . The tool is written as an Excel spreadsheet. Enter the concentration (as ppm or mg/m3) in the appropriate box, enter the molecular weight from the handy table shown on the right hand side and the result will be calculated. The converter uses 1 atmosphere pressure and 25oC as a default, but other values can be entered if needed.

Please let us know if you have any comments about the converter, good or bad. If there are any other gases or vapors you would like to see added to the table or other functionality added to the converter, please leave a comment to let us know.

Tuesday, April 10, 2012

Industry News: CSA Publishes New Standard on Chemical Sterilization

The Canadian Standards Association (CSA) has just published its new standard “Chemical Sterilization of Reusable Medical Devices in health Care Facilities” Z314.23-12, available from either CSA or the American National Standards Institute.

CSA Describe the new Standard as follows

This is the first edition of CSA Z314.23, Effective chemical sterilization in health care facilities. It is one of a series of CSA Standards dealing with the safe and effective sterilization of medical supplies and equipment. It supersedes CAN/CSA-Z314.2, Effective sterilization in health care facilities by the ethylene oxide process, published in 2009, 2001, 1991, 1984, and 1977.

This Standard specifies essential elements in implementing a program for using chemicals to sterilize medical devices in health care facilities. Such chemicals can be vapour, gaseous, or liquid and are delivered in validated concentrations and quantities in defined sterilizers.
The body of this Standard contains requirements that are common to all chemical sterilization processes, whereas requirements specific to a particular chemical sterilization technology are contained in Annexes A to E.
The following chemical sterilants are currently approved for use in sterilizers in Canada and are addressed in this Standard:
(a) gaseous and vapour chemicals:
(i) ethylene oxide;
(ii) hydrogen peroxide;
(iii) ozone; and
(iv) hydrogen peroxide-ozone; and
(b) liquid chemicals: peracetic acid.
Exposure to chemical sterilants can present risks to health care personnel and patients; this Standard includes measures to minimize the risk of such exposure as well as discharge to the environment of sterilizing chemicals and by-products.

Further details are available at CSA's website.