Top Five Chemicals Resulting in Injuries from Acute Chemical Incidents — Hazardous Substances Emergency Events Surveillance, Nine States, 1999–2008

Ayana R. Anderson, MPH

Division of Toxicology and Human Health Sciences, Agency for Toxic Substances and Disease Registry, CDC

Abstract

Problem/Condition: The Toxic Substances Control Act Chemical Substance Inventory lists >84,000 chemicals used in commerce (http://www.epa.gov/oppt/existingchemicals/pubs/tscainventory/basic.html). With chemicals having a multitude of uses, persons are potentially at risk daily for exposure to chemicals as a result of an acute chemical incident (lasting <72 hours). Depending on the level of exposure and the type of chemical, exposure can result in morbidity and, in some cases, mortality.

Reporting Period: 1999–2008.

Description of System: The Hazardous Substances Emergency Events Surveillance (HSEES) system was operated by the Agency for Toxic Substances and Disease Registry during January 1991-September 2009 to collect data that would enable researchers to describe the public health consequences of chemical incidents and to develop activities aimed at reducing the harm from such incidents. This report identifies the top five chemicals that caused injuries in the nine states (Colorado, Iowa, Minnesota, New York, North Carolina, Oregon, Texas, Washington, and Wisconsin) that participated in HSEES during its last 10 full years of data collection (1999–2008).

Results: Of the 57,975 incidents that were reported, 54,989 (95%) involved the release of only one chemical. The top five chemicals associated with injury were carbon monoxide (2,364), ammonia (1,153), chlorine (763), hydrochloric acid (326), and sulfuric acid (318). Carbon monoxide and ammonia by far caused the most injuries, deaths, and evacuations. Chlorine, while not in the top 10 chemicals released, was in the top five chemicals associated with injury because of its hazardous properties.

Interpretation: Multiple measures can be taken to prevent injuries associated with the top five chemicals. Because many carbon monoxide releases occur in residential settings, use of carbon monoxide detectors can prevent injuries. Substituting chemicals with less lethal alternatives can result in mitigating injuries associated with ammonia. Routine maintenance of equipment and engineering controls can reduce injuries associated with chlorine and sulfuric acid, and proper chemical handling training can reduce injuries associated with hydrochloric acid.

Public Health Implications: Understanding the most frequently reported locations where carbon monoxide, ammonia, chlorine, hydrochloric acid, and sulfuric acid are released along with the most frequently reported contributing factors can help mitigate injuries associated with these releases. Prevention initiatives should focus on educating the public and workers about the dangers of these chemicals and about proper handling of these chemicals along with routine maintenance of equipment.

Introduction

Every year thousands of chemicals are manufactured and transported in the United States. As the use of chemicals increases, so does the likelihood of unintentional releases (1,2). Acute chemical releases (releases that last <72 hours) can pose a great public health impact, persons exposed can be injured, and serious exposures (e.g., an exposure to high levels of toxic chemicals such as carbon monoxide) can result in death. Collecting data on chemical releases is one method to determine which chemicals have a greater public health impact, protect public health, improve industry safety, and reduce impacts on the environment (3).

The Hazardous Substances Emergency Events Surveillance (HSEES) database provides information on the characteristics and spatial and temporal dimensions of hazardous chemical releases within the states that participated in the surveillance system. This report summarizes the top five chemicals causing injury occurring in selected states during 1999 to 2008 and is a part of a comprehensive surveillance summary (4). Public and environmental health and safety practitioners, worker representatives, emergency planners, preparedness coordinators, industry managers, emergency responders, and others who prepare for or respond to chemical incidents can use the findings in this report to prepare for and prevent chemical incidents and injuries.

Methods

This report is based on data reported to HSEES by health departments in nine states (Colorado, Iowa, Minnesota, New York, North Carolina, Oregon, Texas, Washington, and Wisconsin) that participated in HSEES during its last 10 full years of data collection (1999–2008). Data from 2009 were not included because several states ended data collection mid-year. Case definitions, exclusion criteria, and 2006 changes in reporting guidelines used for this analysis are described (Box).

This report describes the characteristics of the chemical releases (i.e., frequency of evacuations, contributing factors, industries in which incidents occurred, severity of injury, and type of injuries) associated with the top five chemicals that caused injuries. HSEES defined an injured person as a person who experienced at least one documented acute (i.e., occurring in <24 hours) adverse health effect or who died as a consequence of the event; injured persons must have had at least one injury type or symptom, and up to seven could be listed (5). Descriptive analyses were performed by using SAS software (version 9.2).

Results

During 1999-2008, of the 57,975 chemical release incidents that were reported in HSEES, 54,989 (95%) involved only one chemical being released. A total of 13,196 persons were reported to have been injured in single chemical releases. Chemicals were ranked by the number of injuries that each chemical caused. The top five chemicals associated with injury were carbon monoxide (2,364), ammonia (1,153), chlorine (763), hydrochloric acid (326), and sulfuric acid (318). These top five chemicals accounted for 1,383 (3%) of total single chemical releases but 4,924 (37%) of all injured persons. Releases of carbon monoxide resulted in the highest number of injured persons (2,364) and also the largest number of incidents that required evacuations (222). However, releases of ammonia resulted in more persons being evacuated (14,536) than the other top five chemicals (Table 1). The majority of the top five chemical releases occurred in fixed facilities (range: 70%-97%). Hydrochloric acid and sulfuric acid had a high frequency of releases occurring during transportation (30% and 15%, respectively) (Table 1).

For each HSEES incident, up to two contributing factors can be reported. The various contributing factors that were involved with the top five chemical releases are summarized (Table 2). Equipment failure was the most commonly reported contributing factor for ammonia (46%), carbon monoxide (45%), and sulfuric acid releases (41%). Human error (defined by HSEES as a mistake made by a person) was the most frequently reported contributing factor for chlorine (37%) and hydrochloric acid releases (41%). Ammonia releases had a high percentage of releases (16%) that involved intentional or illegal acts due to its use in illegal methamphetamine production.

Industries were identified by using the Standardized Industrial Classification (SIC) for 1999–2001 data, and the 2002 North American Industry Classification System NAICS (2002–2008 data) (6). The top five chemicals were released in various industries (Table 3). The industry/location that had the highest percentage of injured persons involving carbon monoxide releases was other services (which includes private residences, salons, auto repair, and religious organizations (n = 386 [16%]); most of which occurred in private residences. The industry of real estate, rental, and leasing reported the second highest percentage of injured persons associated with carbon monoxide releases.

In ammonia incidents, the industry with the highest frequency of injured persons was manufacturing of food, textile, and apparel (451 [39%] of 1,153 injured persons). The subsector food manufacturing had the highest number of injured persons and agriculture, forestry, fishing, and hunting had the second highest frequency of persons injured from ammonia releases.

Manufacturing of paper, printing chemicals, petroleum, leather, lumber, and stone resulted in 194 (25%) of 763 injured persons associated with chlorine releases. The subsector paper and chemical manufacturing industries had the most injured persons followed by arts, entertainment, and recreation for chlorine releases.

The transportation and warehousing industry and educational services represented the highest frequencies of the 326 injured persons associated with hydrochloric acid releases. Manufacturing of metal, electrical, transport, and professional and manufacturing of paper, print chemicals, petroleum, leather, lumber, and stone represented the two highest subsectors of the 318 injured persons for sulfuric acid releases.

For all of the top five chemical releases, the majority of injured persons (range: 58%–68%) were treated at a hospital but not admitted. Carbon monoxide had the highest percentage of fatalities; 3% of injured persons died. Chlorine had the lowest frequency of fatalities, less than 1% (Table 4). For sulfuric acid, ammonia, and hydrochloric acid, the majority of injured persons were employees (235 [74%], 716 [62%], and 179 [55%] respectively). For carbon monoxide and chlorine releases, the majority of injured persons were from the general public (49% and 48% respectively) (Table 5).

The frequencies of the injuries reported are summarized (Table 6). The most frequently reported injury for ammonia, chlorine, and hydrochloric acid releases was respiratory irritation. Dizziness was the most frequently reported injury for persons exposed to carbon monoxide, and burns were the most frequently reported injury for sulfuric acid releases.

Discussion

Four of the top five chemicals (ammonia, chlorine, hydrochloric acid, and sulfuric acid) have been documented as being the most frequently reported releases involved in injuries and evacuations (7–9). One quarter of all 354 deaths during this time period were attributable to these five chemicals. These five chemicals were also the top five chemicals released in the top five industries that resulted in injuries (10). To prevent future adverse public health consequences associated with release of the top five chemicals, public health needs to take a multifaceted approach that focuses on education about proper handling practices of the chemicals, the potential dangers of acute releases, and, when applicable, promotion of the use of safer alternatives.

Carbon Monoxide

CO is an odorless, colorless gas that can cause sudden illness and death. CO fumes are created during combustion and can build up in enclosed or semi-enclosed spaces. The most common symptoms of CO poisoning are headache, dizziness, weakness, nausea, vomiting, chest pain, and confusion (10). High levels of CO inhalation can cause loss of consciousness and death (11). This analysis indicated that a high frequency of CO releases occur in private residences. The public should receive prevention messages, particularly before and during power outages. To help prevent CO exposure, persons can equip their homes with CO detectors. Some local health agencies, firefighters, and local media outlets have assisted with CO detector distribution and promotion (12). More information about preventing CO releases is available at http://www.cdc.gov/co/faqs.htm.

Ammonia

Ammonia is a colorless gas with a very distinct odor that is familiar to many persons because it is used in smelling salts, many household and industrial cleaners, and window-cleaning products. Ammonia gas dissolved in water is called liquid ammonia or aqueous ammonia. Once exposed to open air, liquid ammonia quickly turns into a gas (13). Exposure to high levels of ammonia can cause irritation and serious burns on the skin and in the mouth, throat, lungs, and eyes. At very high levels, ammonia can cause death (14). In HSEES data, over half of the injured persons in ammonia releases occurred in agriculture and food manufacturing. Ammonia is used as a refrigerant in the food manufacturing; industries could use refrigerant gases that are not as flammable or toxic as ammonia (e.g., carbon dioxide) (14,15) to reduce morbidity and mortality attributable to future incidents. Ammonia also is applied directly into soil on farm fields and is used to make fertilizers for farm crops, lawns, and plants (16). A substantial number of incidents with injuries were caused by illegal acts, most likely ammonia fertilizer tank thefts to produce illegal methamphetamine (17). Various substitutions and other theft deterrents for ammonia can be implemented (17).

Chlorine

Chlorine is a toxic gas with an irritating odor. Because it is heavier than air, it tends to accumulate at the bottom of poorly ventilated spaces. At low levels of exposure (<15 ppm), nose, eye, and throat irritation can occur. Immediate chest pain, coughing, changes in breathing rate, and vomiting might occur at 30 ppm and lung damage at 60 ppm. After a few minutes of exposure to 1,000 ppm, death can occur (18). Chlorine is an important industrial chemical used in the production of thousands of products (e.g., vinyl chloride to make polyvinyl chloride plastics, refrigerants, aerosols, silicones, and foams). Chlorine also is used for water disinfection (in water treatment plants and swimming pools) and pulp and paper bleaching (18). In this analysis, the majority of injuries in chlorine releases occurred in paper and printing manufacturing and in entertainment and recreation (swimming pools and water parks). Using sodium hydrosulfite and hydrogen peroxide as substitutes can help reduce injuries attributable to chlorine releases in the paper and printing manufacturing industry (19). A 2012 study found that, compared with chlorine releases in paper manufacturing, hydrogen peroxide had fewer injured persons per release with injured persons and fewer injured persons for all releases (20). Educational initiatives that focus on proper handling and storing procedures for pool chlorine can help reduce injuries (20). Because equipment failure represented 37.1% of the incidents that resulted in chlorine releases, routine maintenance of equipment and engineering controls can reduce failure and injuries (20).

Hydrochloric Acid

Hydrochloric acid is a clear, colorless solution of hydrogen chloride in water. It is a highly corrosive, strong mineral acid also known as muriatic acid (21,22). Hydrochloric acid is used to manufacture fertilizers, dyes, ore refining, rubber and pickling of metal (23). It has numerous smaller-scale applications, including household cleaning and commercial pool cleaning. Hydrochloric acid is corrosive to human tissue; upon exposure it can harm respiratory organs, eyes, skin, and intestines irreversibly (22). Persons exposed to unsafe levels of hydrochloric acid and have skin or eye irritation need to be decontaminated (24). To prevent injuries, persons handling hydrochloric acid should wear skin, eye, and respiratory protection (20). Because the majority of the injuries reported in hydrochloric acid releases occurred in transportation and warehousing, persons who work in this industry must be aware of the dangers that are associated with the chemicals they are transporting and know how reactive they are. One method to ensure that workers are following proper protocols for handling hydrochloric acid is to install cameras at warehouses and on transporting vehicles so supervisors can review videos to observe worker handling practices (24).

Sulfuric Acid

Sulfuric acid (also called sulphine acid, battery acid, and hydrogen sulfate) is a clear, colorless, oily liquid that is very corrosive. It is used in the manufacture of fertilizers, explosives, other acids, and glue; in the purification of petroleum; in the pickling of metal; and in lead-acid batteries (used in most vehicles) (25). Because of its corrosiveness, sulfuric acid at a high concentration can cause very serious damage (e.g., chemical and thermal burns). Sulfuric acid burns the cornea and can lead to permanent blindness if splashed onto eyes. Skin and eye protection should be worn whenever using sulfuric acid. If sulfuric acid gets into the eyes or on a person's skin, the eyes must be irrigated immediately, and skin should be washed with water (26). In the HSEES database, the most commonly reported industry for sulfuric acid injuries was manufacturing and these incidents had a high frequency of equipment failures. Ongoing maintenance can prevent releases, in addition to education about proper handling of the chemical.

Limitations

The findings in this report are subject to at least five limitations. First, despite the attempts to make the case definition the same among states, results are not comparable between states because reporting to HSEES was voluntary and data sources varied by state. Second, the results from these nine states might not be representative of the entire United States. Third, inconsistencies within and across states likely exist because reporting capacity (e.g., staffing) or local requirements varied. Specifically, certain states and localities had more stringent reporting regulations than the federal regulations or had more resources to conduct surveillance, possibly resulting in more reported incidents. These factors might have influenced the quality and number of reports or level of detail provided about the incidents. Fourth, the changes in reporting guidelines in 2006 (e.g., reports of smoke stack emissions above permitted values of carbon monoxide were removed because they rarely resulted in a public health impact) could have led to some chemicals being unreported or bias towards those that cause injuries. Finally, incidents occurring in transportation and warehousing might often be related to a vehicular accidents and, therefore, associated injuries might be related to the trauma of the accident rather than the chemical.

Conclusion

Understanding the nature of the top five chemicals that resulted in injuries can help researchers effectively target reductions in morbidity and mortality. Carbon monoxide and ammonia by far caused the most injuries, deaths, and evacuations and therefore need more attention toward prevention. Three of the chemicals had high reports of releases in various industry settings (ammonia in food manufacturing, chlorine in paper and printing manufacturing, and hydrochloric acid in warehousing). The Occupational Safety and Health Administration (OSHA) regulates worker exposure to chemicals by requiring proper education and training (27). In addition, all employers with hazardous chemicals in their workplace must have labels and safety sheets for their exposed workers (27). OSHA provides a Hazard Communication Standard that requires that information about chemical hazards in the work setting and associated protective measures are disseminated to workers (26). In addition, controlling exposures in the industries that have a high frequency of the top five chemicals released can prevent morbidity and mortality. OSHA has a hierarchy of controls that can determine how to implement feasible and effective controls. The hierarchy (in order of effectiveness) includes elimination, substitution, engineering control, administrative controls, and personal protective equipment (PPE) (28). Although these controls can reduce chemical hazards, there are some potential limitations with trying to implement the controls. Elimination and substitution, even though they might be the most effective at reducing hazards, can be difficult to implement. Initial costs for engineering controls (which remove a hazard or place a barrier between a worker and a hazard) can be high; however, long-term operating costs are lower and can be cost saving in other areas of the industry operations. Administrative control and PPE are the least effective of the hierarchy of control and are not well controlled. They are inexpensive to establish but can be costly to sustain (28). Overall, proper employee training, implementing the hierarchy of controls, raising awareness among the general public, and in some cases promoting safer alternatives can reduce morbidity and mortality associated with these top five chemicals.

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