2.
Accidental Releases
Authors
This chapter was prepared by Will Humble, R.S., M.P.H., Risk Assessment and Environmental Epidemiology Section, Arizona Department of Health.
Introduction
This chapter analyzes emergency events in Arizona caused by accidental releases of hazardous substances. These releases can cause adverse health effects among exposed individuals, especially facility employees, first responders such as firemen and hazardous materials teams, and members of the general public.
The data used in the analysis is from the Arizona Department of Environmental Quality (ADEQ) Emergency Response Unit, and from Hall et al. at the Agency for Toxic Substances and Disease Registry (ATSDR).
Methodology
The best method for estimating the number and types of potential health effects would be to analyze data collected in Arizona; however, these data are not available. Therefore, the Committee used data collected by other states in order to estimate health effects in Arizona.
The Committee used data Hall et al. (1994) compiled from Colorado, Iowa, New Hampshire, New York, North Carolina, Oregon, Rhode Island, Washington and Wisconsin. These data show that:
o About 15% of the 3,125 of emergency events involving hazardous substances from 1990 to 1992 resulted in injury (health effects)
o 1,446 persons were injured
o The average number of persons injured per event was 3.1, with an average of 1.7 health effects per injured person (2,501 injuries overall)
o 67% of injured persons were employees
o 14% were first responders
o 19% were members of the general public
o 11 deaths were reported during these events, 8 of which were facility employees.
The types of health effects found by the analysis are displayed in Table 2.1.
Table 2.1 Types of Injuries Sustained During Emergency Events Involving Hazardous Substances--Selected States (Hall, 1994)
-------------------------------------------------------------------------------- | Type of Injury | Number of | Percent * | | | Injuries | | ================================================================================ | Respiratory irritation | 933 | 37 | -------------------------------------------------------------------------------- | Eye irritation | 571 | 23 | -------------------------------------------------------------------------------- | Nausea | 222 | 9 | -------------------------------------------------------------------------------- | Chemical burns | 153 | 6 | -------------------------------------------------------------------------------- | Dizziness or other CNS symptoms | 126 | 5 | -------------------------------------------------------------------------------- | Skin irritation | 96 | 4 | -------------------------------------------------------------------------------- | Physical trauma | 82 | 3 | -------------------------------------------------------------------------------- | Headache | 80 | 3 | -------------------------------------------------------------------------------- | Heat stress | 49 | 2 | -------------------------------------------------------------------------------- | Thermal burns | 26 | 1 | -------------------------------------------------------------------------------- | Vomiting | 8 | 0.3 | -------------------------------------------------------------------------------- | Other | 155 | 6 | -------------------------------------------------------------------------------- | Total | 2,501 | 99.3 | -------------------------------------------------------------------------------- | * Percentage does not equal 100 due to rounding. | | | --------------------------------------------------------------------------------
This analysis uses the number of on-scene responses by the ADEQ Multi-Media Response Team during Fiscal Year 1993 to estimate the number of hazardous materials events that may be expected to occur on an annual basis in Arizona.
It is recognized that emergencies may occur that do not require the Emergency Response Unit; however, the majority of incidents involving hazardous materials would be included.
The Arizona Risk
ADEQ Emergency Response personnel supervised 162 on-scene responses in Fiscal Year 1993, with a total of 433 incidents reported, and 104 referrals to other agencies (ADEQ, 1993). The number of injuries that may have occurred during these events are not available.
The Committee therefore used ADEQ data on the number of emergency events involving hazardous substances, and ATSDR (national) data on the frequency of injuries associated with these events.
The number of persons injured and the number of health effects that may be expected per event were calculated using the following expression:
----------------------------------------------------------------------------- | I = (E)(F)(N) | | | | where: | | | | I = Number of persons injured per year (injured persons per year) | | | | E = Number of emergency events with hazardous substances per | | year (162 events per year) | | | | F = Fraction of events causing injury (0.15) | | | | N = Number of persons injured per injury event (3.1 injured persons | | per event) | -----------------------------------------------------------------------------
The above expression results in an estimate of 75 persons injured per year as a result of emergency events involving hazardous substances.
Multiplying the average number of health effects per injured person of 1.7 from the ATSDR data by 75 persons results in an estimate of 127 health effects per year.
Applying the percentages of each health effect from the ATSDR report to the Arizona estimates produces the health effect distribution shown in Table 2.2 on the following page.
Table 2.2 Estimate of the Annual Number of Injuries That May Be Sustained During Emergency Events Involving Hazardous Substances in Arizona
--------------------------------------------------------------------------------- | Type of Injury | No. of | Percentage * | | | Injuries | | ================================================================================= | Respiratory irritation | 48 | 37 | --------------------------------------------------------------------------------- | Eye irritation | 29 | 23 | --------------------------------------------------------------------------------- | Nausea | 11 | 9 | --------------------------------------------------------------------------------- | Chemical burns | 8 | 6 | --------------------------------------------------------------------------------- | Dizziness or other CNS symptoms | 6 | 5 | --------------------------------------------------------------------------------- | Skin irritation | 5 | 4 | --------------------------------------------------------------------------------- | Physical trauma | 4 | 3 | --------------------------------------------------------------------------------- | Headache | 4 | 3 | --------------------------------------------------------------------------------- | Heat stress | 3 | 2 | --------------------------------------------------------------------------------- | Thermal burns | 1 | 1 | --------------------------------------------------------------------------------- | Vomiting | 1 | 0.3 | --------------------------------------------------------------------------------- | Other | 7 | 6 | --------------------------------------------------------------------------------- | Total | 127 | 99.3 | --------------------------------------------------------------------------------- | * Percentage does not equal 100 due to rounding. | | | ---------------------------------------------------------------------------------
Estimate of Deaths During Emergency Events
In order to estimate the annual number of deaths that may occur during emergency events, a rate for deaths per event was derived from Hall et al.
The total number of reported deaths (11) was divided by the total number of events (3,125) giving a death rate per event of 0.0035.
Multiplying the number of events in Arizona during Fiscal Year 1993 by this rate results in an estimate of 0.5 deaths per year from emergency events involving hazardous substances. The rate estimate includes employees, first responders and the general public.
Uncertainties
The methods used to estimate the number of injuries and deaths rely on data collected in other states and analyzed by the ATSDR. The data used may not accurately reflect the types and numbers of health effects that occur in Arizona as a result of emergency events with hazardous substances.
The numbers generated must be considered a rough estimate of the number of health effects from emergencies involving hazardous substances in Arizona.
Conclusion
o The estimated annual number of persons who may be injured during emergency events involving hazardous substances in Arizona is 75.
o The estimated number of health effects that may be experienced by these persons is 127.
The most frequently expected health effects include respiratory and eye irritation, and nausea. The estimated number of annual deaths as a result of these effects is 0.5. The mortality figure includes facility employees, first responders and the general public.