Small spills of sodium hydrosulfide collect in a pit at a paper mill unloading station while workers unload tank trucks of sodium hydrosulfide. After unloading several trucks, an employee opens a valve to empty the collection pit into the mill's industrial waste sewer. The spilled sodium hydrosulfide enters the sewer at the same time sulfuric acid is being added to adjust mill waste pH. The ensuing reaction releases a cloud of deadly hydrogen sulfide gas, engulfing a group of nearby construction workers. Two workers die almost instantly and eight others suffer serious injuries.
Cleaning up at the end of the day, employees at a sign company combine waste chemicals from several 15-gallon containers into 55-gallon drums. The employees don't realize they are mixing waste nitric acid with lacquer thinner. Within minutes, employees hear a hissing sound. The hiss grows to a roar as liquid sprays from one of the drums. As the employees run for safety, the drum explodes. Thirty-one people are injured.
CSB Report
Managing reactive chemicals is serious business. How serious was revealed in the report Improving Reactive Hazard Management, released by the U.S. Chemical Safety and Hazard Investigation Board (CSB) in September 2002 (www.csb.gov/info/docs/2002/DS-Reactives.pdf). The report analyzed 167 serious incidents in the United States from January 1980 to June 2001 that resulted in 108 deaths.
The CSB report concluded there are significant gaps in federal safety regulations. Over 50 percent of the incidents involved chemicals not covered by OSHA and EPA process safety regulations.
The CSB also found that the National Fire Protection Association (NFPA) hazard ranking diamond, commonly used by safety and health professionals to quickly assess chemical risks, is not an effective guide for reactive chemical safety. Sixty percent of the incidents involved chemicals that were either not rated by the NFPA or are considered to have "no special hazard" an NFPA instability rating of 0.
The CSB report recommended amending OSHA and EPA regulations to provide more comprehensive coverage of reactive hazards. OSHA and EPA have been reluctant to implement the CSB recommendations, but are working with the CSB and stakeholders to determine what to do next (www.occupationalhazards.com/full_story.php?WID=7217).
Of course, when federal regulators fail to act, state agencies get involved. The New Jersey Department of Environmental Protection recently proposed adding 30 new reactive hazardous substances and 43 chemical groups to its list of extraordinarily hazardous substances. The list triggers requirements for detailed risk management planning.
Management Guidlines
But new regulations are never a complete solution. Effective management of reactive chemicals requires the development and implementation of good management practices. The CSB report found that "...only limited guidance on the management of reactive hazards... is available to industry through professional societies, standards organizations, government agencies or trade associations."
In response, the American Institute of Chemical Engineers' Center for Chemical Process Safety (CCPS, www.aiche.org/ccps) developed new guidelines for managing reactive chemicals. Essential Practices for Managing Chemical Reactivity Hazards should be in the library of every safety and health professional involved with chemical safety. OSHA is working with the CCPS to make the contents of the document available to the public free of charge.
Additional reactive chemical information is available on the Internet. And the CSB Web site is an excellent place to start your education. The site includes a library of CSB news releases, investigation reports and Web broadcasts of public hearings. The investigation reports, and associated Web broadcasts, are especially interesting, identifying important pitfalls and lessons learned.
The CSB's Chemical Incident Reports Center contains nearly 3,000 incident records searchable by keyword, location, chemical, incident type, date range and other descriptors.
Want to stay up to date on the latest reactive material incidents? Sign up for the CSB's incident electronic mailing list.
The National Oceanic and Atmospheric Administration's (NOAA) Chemical Reactivity Worksheet (response.restoration.noaa.gov/chemaids/react.html) is a useful tool for identifying reactivity hazards of over 6,000 common hazardous chemicals.
The user simply selects chemicals to populate a matrix with chemical reactivity and compatibility information. The worksheet matrix makes it easy to identify reactivity and compatibility problems between the selected chemicals. The matrix may be printed or saved as a tab-delimited text file by clicking on the program's print button. Saved files can then be imported into a spreadsheet or word processor table for more formal reporting.
Be sure to work the exercises on the "Reactivity Problem Set" (response.restoration.noaa.gov/chemaids/react/problems.html) after downloading and installing the NOAA Worksheet. The exercises not only teach proper use of the worksheet, they also provide additional insight into the broad range of reactivity hazards.
OSHA recently unveiled its Chemical Reactivity Safety Web site (www.osha.gov/dep/reactivechemicals/index.html). The Web site features information on the recognition, evaluation and control of chemical reactive hazards, and includes compliance requirements and available training resources.
"Reactive Material Hazards, What You Need to Know" is a free CCPS publication available at www.aiche.org/ccps/pdf/reactmat.pdf. The document provides a general overview of reactive hazards. The CCPS also issues the monthly Process Safety Beacon (www.aiche.org/ccps/safetybeacon.htm). These monthly safety bulletins cover a variety of topics that make great safety meeting fodder. Information on other CCPS publications that address reactive chemical hazards, and a schedule of classes on reactive chemical safety practices, is available at www.aiche.org/ccps.
European Community
The European Community is another source of chemical reactivity information and tools.
The United Kingdom's Health and Safety Executive provides an interesting worker safety education publication Chemical Reaction Hazards and the Risk of Thermal Runaway (www.hse.gov.uk/pubns/indg254.htm). The document provides an overview of hazards associated with exothermic chemical reactions. Other useful HSE documents are available at www.hse.gov.uk/pubns/index.htm.
The Thematic Network on Hazard Assessment of Highly Reactive Systems, or HarsNet (www.harsnet.de/homepage.htm), is an ambitious undertaking. HarsNet is a forum where universities, research centers and industries collaborate to develop and disseminate information used for hazard assessment of reactive systems.
A work in progress, HarsNet currently includes:
- HarsBook, a reference book on exothermic reaction hazards
- HarsMeth, a chemical process safety assessment procedure
- HarsBase, a collection of links to chemical reaction safety related data
Designed for small- and medium-sized chemical companies, HarsMeth includes a tutorial on reactive chemical safety. The HarsMeth assessment tool uses a comprehensive set of checklists to identify, evaluate and control reactive chemical hazards. Checklists address basic chemical information, reaction and process information, engineering and process design, materials storage and key management practices.
With Improving Reactive Hazard Management, CSB identified critical issues that must be addressed to improve worker and public safety. Yes, new assessment tools and guidelines have been developed. But real progress will not be made unless these new tools are put into practice. Safety, health and environmental professionals must step forward if we are going to play an effective role in identifying and eliminating reactive chemical hazards.
Contributing Editor Michael Blotzer, MS, CIH, CSP is an occupational hygiene and safety professional, writer and computer enthusiast who brakes for animals on the information superhighway. He can be reached by mail addressed to Occupational Hazards, by fax at (309) 273-5493, or by electronic mail at [email protected].