Public Health Response to Acute Chemical Incidents — Hazardous Substances Emergency Events Surveillance, Nine States, 1999–2008

Natalia Melnikova, MD, PhD

Jennifer Wu, MS

Maureen F. Orr, MS

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

Abstract

Problem/Condition: Acute chemical incidents (i.e., uncontrolled or illegal release or threatened release of hazardous substances lasting <72 hours) represent a substantial threat to the environment, public health and safety, and community well-being. Providing a timely and appropriate public health response can prevent or reduce the impact of these incidents.

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 (ATSDR) during January 1991–September 2009 to describe the public health consequences of chemical releases and to develop activities aimed at reducing the harm. This report summarizes types, frequency, and trends in public health actions taken in response to hazardous substance incidents 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 HSEES incidents that occurred during 1999-2008, a total of 15,203 (26.2%) incidents resulted in at least one public health action taken to protect public health. Evacuations were ordered in 4,281 (7.4%) HSEES incidents, shelter in place was ordered in 509 (0.9%) incidents, and access to the affected area was restricted in 10,345 (25.9%) incidents. Decontamination occurred in 2,171 (3.7%) incidents; 13,461 persons were decontaminated, including 1,152 injured persons. Actions to protect public health (e.g., environmental sampling or issuance of health advisories) were taken in 6,693 (11.5%) incidents. The highest number of evacuations and orders to shelter in place occurred in Washington (n = 558 [16.1%] and n = 121 [3.2%], respectively). Carbon monoxide and ammonia releases resulted in the highest percentage of orders to evacuate and shelter in place. The most frequently reported responders to chemical incidents were company response teams.

Interpretation: The most frequent public health response was restricting access to the area (26% of incidents), public health actions (12%), evacuation (7%), decontamination (4%), and shelter-in-place (1%). Ammonia and carbon monoxide were associated with adverse health effects in the population and the most public health response actions. Therefore, these chemicals can be considered a high priority for prevention and response efforts.

Public Health Implications: States and communities can collaborate with facilities to use the information collected through community right-to-know legislation and this report to improve chemical safety and protect public health and the environment, such as being prepared to handle the most common chemicals in their area and probable public health actions.

Introduction

Chemical incidents can cause adverse health effects, serious injuries or deaths, and environmental damage. The prevention of incidents involving hazardous substances is the priority of public authorities at all levels, industries, and employees and their representatives. Regardless, toxic chemical incidents continue to occur, affecting the health and lives of many. Therefore, efforts to prevent or decrease exposures to chemical hazards during these incidents are vital (1). Protective actions during an incident involving the release of hazardous substances are steps that are taken to preserve the health and safety of the members of the public and emergency responders (2,3).

Evacuating members of the public out of an area affected by a hazardous material release or requesting that they remain indoors and shelter in place by closing up the building and waiting for the danger to pass are two basic tools used by emergency response officials to protect the public when they are threatened by exposure to chemical spills (2,3). Depending on the severity of the situation, additional actions taken might include decontamination and the closing of buildings, roads, bridges, and parking lots.

The Hazardous Substances Emergency Events Surveillance (HSEES) system provides information on the characteristics and spatial and temporal dimensions of hazardous chemical releases within the states that participated in the surveillance system (4). This report summarizes the public health response to chemical incidents occurring in selected states during 1999-2008 and is a part of a comprehensive surveillance summary (1). Public and environmental health and safety practitioners, worker representatives, emergency planners, preparedness coordinators, industries, 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 complete calendar years of data collection, 1999-2008. Data from 2009 were not included because several states ended data collection mid-year. A detailed description of the HSEES data used in this analysis is found elsewhere (1). Case definitions, exclusion criteria, and 2006 changes in reporting guidelines used for this analysis are described (Box).

The types, frequency, and trends in public health response were assessed on the basis of evacuations, shelter-in-place orders, area access restrictions, decontamination, and other actions to protect public health, as well as information on who responded to the incident. These data were analyzed using statistical software to produce descriptive statistics.

Variable Definitions

Transportation-related chemical incidents are those that occur 1) during surface, air, pipeline, or water transport of hazardous substances and 2) before the chemical was totally unloaded from a vehicle or vessel. All other incidents are considered fixed-facility incidents.

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 incident; injured persons must have had at least one injury type or symptom, and up to seven could be listed (5).

The public health response is defined as the actions taken to protect public health as a result of the incident (e.g., evacuation, health advisory, well survey, alternate water, fishing ban, prohibit consumption of livestock or produce, health investigation, shutdown of water intakes, or environmental sampling).

Results

Approximately 26% (n = 15,203) of the total 57,975 HSEES incidents involved at least one public health action, including evacuation, sheltering in place, restricted access to the affected area, and other actions to protect public health. A total of 77% (n = 11,746) of these actions resulted from transportation incidents and 23% (n = 3,457) resulted from fixed-facility incidents.

Shelter in Place

Sheltering in place, or remaining inside of a sealed building until a release dissipates, was ordered in 1% of incidents (n = 509), (Figure 1). Approximately 84% (n = 428) of these incidents were associated with fixed facilities, and 16% (n = 81) were associated with transportation incidents. The highest percentage of incidents that required sheltering in place occurred in Washington, and the lowest occurred in Iowa (Figure 1). Incidents with an order to shelter in place increased during 2000-2004, with minimal changes during 2005-2008 (Figure 2).

Evacuations

An evacuation was ordered in 7% (n = 4,281) of incidents. Approximately 90% (n = 3,858) of these incidents were associated with fixed facilities and 10% (n = 423) with transportation. The percentage of chemical incidents with an ordered evacuation varied by state and ranged from a low of 2% (n = 517) in Texas to a high of 16% (n = 558) in Washington (Figure 1). The percentage of incidents with an ordered evacuation decreased from 9% in 1999 to 6% in 2005 and then increased to 9% in 2008 (Figure 2). The total length of all evacuations combined was 43,686 hours, with an average of 11 days. The shortest evacuation ended within an hour, and the longest continued for 84 days.

At least 367,783 people were evacuated during the reporting period, ranging from a low of 25,209 in 2003 to a high of 63,045 in 1999 (Figure 3). The average number of persons evacuated per year was 36,778. No linear trend in number of persons evacuated over time was detected (R2 = 0.21).

New York had the greatest number of evacuees (n = 125,575), followed by Texas (n = 67,801), Washington (n = 38,305), and North Carolina (n = 37,748). Colorado (n = 10,648) and Oregon (n = 12,942) had the fewest evacuees (Figure 4). The number of evacuees is influenced not only by the percentage of incidents involving evacuations but also by the total number of incidents. New York, Texas, and Washington reported the greatest number of incidents, whereas Oregon and Colorado reported the fewest.

North Carolina, Washington, and Wisconsin had the greatest decrease in number of persons evacuated, whereas Minnesota and Iowa had the greatest increase (Table 1). The most frequent type of evacuation involved an entire building or part of a building (n = 3,176 [75%]). Less common evacuations were of a circle or radius (n = 544; 13%), downwind or downstream (n = 218 [5%]), and circle and downwind or downstream (n = 169 [4%]). The type of evacuation for the remaining evacuations was not defined (n = 112 [3%]). Evacuation information was missing for 590 (1%) incidents.

Analysis of public health actions by substance category was performed for 54,990 incidents that involved only a single substance. The highest number of evacuations were caused by carbon monoxide (n = 784 [20.8%]), followed by ammonia (n = 611 [16.2%]), other inorganic substances (n = 442 [11.7%]), and volatile organic compounds (VOCs) (n = 345 [9.2%]). In addition, incidents involving ammonia, mixtures involving more than one chemical category, other inorganic substances, and VOCs had the highest percentage of orders to shelter in place (20%, 19%, 11%, and 11%, respectively).

Decontamination

Decontamination is used to remove chemicals from contaminated persons to prevent additional contamination of the person and to prevent spreading and secondary contamination of others. Decontamination occurred in 4% (n = 2,171) of incidents; 13,461 persons were decontaminated, including 1,152 injured persons.

Other Public Health Actions

Data on restricted access to a site as a result of a chemical incident have been collected since 2002. Access to the area of the release was restricted in 26% (n = 10,345) of all incidents, categorized according to the largest area restricted (the building [n = 2,792], the room [n = 2,095], the entire facility including grounds [n = 1,123], and a wing or section of the building [n = 1,175]). Routes or roads were closed during 1,188 incidents and parking lots during 401 incidents. Because of the type and amount of chemical released, entrance to other adjacent areas was restricted 3,499 times. Approximately 72% (n = 28,938) of the incidents did not require any restrictions. Area restrictions were unknown for 2% (n = 865) of incidents. Generally, the percentage of incidents with required restrictions increased significantly from 20% (n = 1,275) in 2002 to 30% (n = 1,559) in 2008 (p≤0.001) (Figure 5). New York had the highest percentage of restrictions (n = 4,920 [47%]), and Texas had the lowest (n = 981 [4%]) (Figure 6).

Public health actions were taken during or after 12% (n = 6,693) of incidents. Some incidents involved several different types of actions. The most common actions were conducting environmental sampling (n = 6,463), issuing a health advisory (n = 133), performing a health investigation (n = 54), and conducting well surveys (n = 30).

Responder Category

A single responder category was reported for 53% (n = 30,669) of incidents, and multiple responder categories were reported for 16% (n = 9,217) of incidents. Responder type was not reported for 3,417 incidents. The most frequently reported responder group was a company response team, followed by fire departments, law enforcement agencies, certified hazardous materials teams, the U.S. Environmental Protection Agency, and an emergency medical technician response team (Table 2).

Discussion

Although the highly industrialized states of Texas and New York reported the greatest number of chemical incidents, the highest percentage of incidents resulting in evacuations and orders to shelter in place occurred in Washington (16.1%), followed by New York (14.9%). New York also reported the highest total number of evacuees (125,575) and the highest percentage of incidents requiring restrictions after the incident (45.1%). One possible explanation for this finding is that the high density of industries and population concentrated in New York City, New York, and Seattle, Washington. Differences in state response protocols could be another explanation. Although Texas reported the greatest number of chemical incidents, only 2.2% of these incidents resulted in evacuations. Since 2002, the total number of incidents has decreased; however, the percentage of incidents with area restrictions increased from 19.6% in 2002 to 29.8% in 2008, which might indicate an increased awareness and use of actions to reduce public exposures.

In 1986, Congress enacted the Emergency Planning and Community Right-to-Know Act (6) to establish requirements for federal, state, and local governments; tribes; and industries regarding emergency planning and the right of the public to have information about reported hazardous and toxic chemicals. The community right-to-know provisions help increase knowledge of and access to information on chemicals at individual facilities, as well as their uses and releases into the environment for members of the general public. HSEES was created to help identify areas most vulnerable to chemical incidents and to plan public safety interventions such as establishing evacuation routes and educating the community of shelter-in-place instructions. Public information programs are especially important for sheltering in place because fleeing from danger is a natural instinct (7). Acute, unintended releases of carbon monoxide, ammonia, and other inorganic substances were among the chemical releases most often associated with adverse health effects in the population (8). The volatility of these chemicals might explain why they cause so many injuries and thus more public health actions. The findings in this reports also showed that company response teams were the most frequently reported responder group in HSEES incidents. This group would benefit from training for protective measures.

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, because of changes in reporting guidelines in 2006, the definition of eligible incidents could vary among states because of the differences in clean-up requirements. Finally, underreporting of incidents that did not have a public health response could have inflated the number incidents with responses.

Conclusion

States and communities can collaborate with facilities to use the information collected through the community right-to-know legislation and from this report to improve chemical safety and protect public health and the environment (e.g., being prepared to handle the most common chemicals in their area and establishing probable public health actions). Additional efforts to increase the community's knowledge about chemicals at individual facilities and their uses and releases into the environment, as well as community knowledge and skills regarding public safety interventions (e.g., evacuations or sheltering in place), can improve outcomes. Improving emergency planning requirements, providing the specificity of chemicals (ammonia and carbon monoxide) and local features and circumstances, and involving the community in the planning process will improve public safety. Providing special training courses for first responders on how to effectively and safely protect the public and themselves can reduce the overall number of injuries. Better prepared first responders and a more educated public will result in fewer public health effects from chemical releases, fulfilling the mission of the HSEES program and the National Toxic Substance Incidents Program, which merged with HSEES in 2010.

References

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