Case Study #6



Case Study – Elemental Mercury Spill

PARTICIPANT VERSION

Objectives

• Given a case definition and a description of a possible case, select the appropriate case classification.

• List effective interview techniques

• Describe specimen collection procedures for a given outbreak situation.

• Identify critical public health messages for a disease or condition.

Instructions

Read each update aloud and, as a team, discuss the questions that follow.

Time Allotted: 1.0 hours

Background Materials

The following training, found at the North Carolina Center for Public Health Preparedness Web Site (), is recommended for Epi Team members without prior outbreak investigation experience. It can be viewed prior to completing the case study.

1. Interviewing Techniques (I is for Investigation, Session 4)

Resources

U.S. Environmental Protection Agency. Mercury spills, disposal, and site cleanup. Environmental Protection Agency. . Updated February 29, 2008. Accessed March 7, 2008.

U.S. Environmental Protection Agency Region 5. Mercury response guidebook (for emergency responders). Attachment B: Guidelines for responding to mercury spills and releases in schools and residences. 2004. . Published July 2004. Accessed January 16, 2008.

North Carolina Center for Public Health Preparedness. Interviewing Techniques. FOCUS on Field Epidemiology [serial online] 2(3). . Accessed February 6, 2008.

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Question 1: What advice should you give the principal?

Question 2: Who else should you notify about the mercury spill?

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Question 3: Would your health department activate its Incident Command System (ICS) in this situation?

Question 4: What is the role of the health department in this type of mercury spill?

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Group Brainstorm

Choose one team member to record answers on a flip chart. As a group, brainstorm about potential questions that might be included in an interview questionnaire for students and staff who may have been exposed to mercury. Out of all of the questions generated, identify the 5 most important to include in the questionnaire.

Role Play

Choose one of the following options to simulate the interview process, using the 5 questions you have just generated.

Option A

One Epi Team member will play the student who broke the thermometer and another team member will act as the interviewer. The pair will act out the interview while the rest of the Epi Team observes. The team member playing the student should use the Student Information Handout available in the facilitator version of the case study.

Option B

The Epi Team should divide into pairs, and each pair should conduct the interview, with one team member acting as the student and one as the interviewer. The team members playing the student should use the Student Information Handout available in the facilitator version of the case study.

After the role play, discuss the next question as a team.

Question 5: What techniques did the interviewer use that were effective?

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Question 6: Do the observed levels of mercury in the air samples indicate the need for decontamination?

Question 7: Should clinical specimens be collected from any students?

If you answered yes:

Question 7a: What type(s) of specimens should be collected?

Question 7b: Who is responsible for collecting the specimens?

Question 7c: Where should specimen samples be sent?

If you answered no:

Question 7d: Why is it not appropriate to collect specimens at this time?

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Activity

As a group, write three (3) key messages to include in a statement to the media. Keep in mind that your goal is to emphasize the danger of inhaling elemental mercury as well as to provide basic information about mercury spill clean-up. For ideas, you can refer to:

• Appendix A: U.S Environmental Protection Agency. Spills, Disposal, and Site Clean-up. . Accessed April 15, 2008.

• Appendix B: Agency for Toxic Substances and Disease Registry. Mercury. 1999. . Accessed January 23, 2008.

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Activity

Based on the information above and the CDC Case Definition for Inorganic Mercury Poisoning () below, classify each of the four students as Suspect, Probable, or Confirmed Cases. Students who do not meet the case definition based on laboratory results may be classified as “Not a Case.”

Suspect: A case in which a potentially exposed person is being evaluated by health-care workers or public health officials for poisoning by inorganic mercury, but no specific credible threat exists.

Probable: A clinically compatible case in which an index of high suspicion (credible threat or patient history regarding location and time) exists for inorganic mercury exposure, or an epidemiologic link exists between this case and a laboratory confirmed cases.

Confirmed: A clinically compatible case in which laboratory tests have confirmed exposure with urine or whole blood mercury levels (>10μg/L)

Signs and symptoms of mercury poisoning could include neuropsychiatric disturbances (e.g., memory loss, irritability, or depression), tremor, paresthesias, gingivostomatitis (mouth sores), flushing, discoloration and desquamation (peeling skin) of the hands and feet, and hypertension.

|Name |Case Classification |

|Seth Hamel | |

|Mike Parsons | |

|Chris Ostrowski | |

|Jack Robbins | |

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Question 8: Are there any actions that your health department can take to prevent future mercury spills in schools?

Group Brainstorm

Often, after an outbreak investigation or a public health emergency, an Epi Team reviews the investigation in a “hot wash” or after-action review. The questions below are examples of questions that could be used in such a review. Choose one member of the Epi Team to record responses on a flip chart. As a group, discuss one or more of the following questions.

• What aspects of the mercury spill investigation were successful?

• All public health emergencies present unique challenges. What characteristics of this emergency made it challenging?

• What areas of the investigation could have been improved?

• If a similar mercury spill occurred in your jurisdiction, do you think that your Epi Team would be prepared to handle it?

References

Occupational and Environmental Epidemiology Branch, NC Department of Health and Human Services. Health consultation: Henry B. Hallyburton Elementary School. Atlanta, GA: Agency for Toxic Substances and Disease Registry, US Department of Health and Human Services; 2007.

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Background – 3 pm, Tuesday, April 15th

The local health department receives a phone call from a local high school principal reporting a mercury spill at the school. The spill occurred around 9 am during a science class when a student broke a large thermometer containing mercury. Several students handled the spilled mercury before the science teacher intervened.

Update – 5 pm Tuesday, April 15th

The environmental health director calls the county emergency manager for clean-up and decontamination assistance. First responders arrive on the scene and begin decontamination and clean-up. Students and staff from the science class have already gone home for the day.

Update – Wednesday, April 16th

Several members of the health department’s Epi Team visit the school to interview students and staff members who may have been exposed to mercury. The purpose of the interviews is to determine the extent of mercury exposure.

Update – Afternoon of Wednesday, April 16th

From your interviews, you find that 4 students handled the mercury for approximately 15 minutes before trying to sweep it up with a broom and throwing some mercury into the sink. None of them took the mercury home, although you plan to test their shoes and clothing.

Meanwhile, the NC Occupational and Environmental Epidemiology Branch (OEE) collected environmental air samples from the classroom to test for mercury. They took air samples in the immediate area around the spill, near the broom used to sweep the mercury, and near the sink where the students reported dumping the mercury and broken thermometer.

Selected results from the air samples are below.

Lumex RA-915 Mercury Vapor Analyzer Reading on April 16, 2008 | |Floor 1 |2,621 ng/m3 | |Floor 2 |3,389 ng/m3 | |Sink |4,737 ng/m3 | |Classroom Door |1,161 ng/m3 | |

Update – Thursday, April 17th

The media has been reporting on the mercury spill. In the news stories, the media has emphasized the health consequences of touching elemental mercury. In fact, research shows that the most hazardous elemental mercury exposure comes from inhaling mercury vapors, not simply touching the mercury. The health educator on your Epi Team would like to correct this misconception while educating the general public about the dangers of mercury exposure and what to do in case of a mercury spill.

Update – afternoon of Thursday, April 17th

You receive laboratory information about the four students who handled the spilled mercury. A summary of the information four students who handled the spilled mercury. A summary of the information is provided below.

Name |Specimens Collected? |Blood mercury (μg/L) |Urine mercury (μg/L) |Symptoms | |Seth Hamel |Yes – April 16th |8 |6 |Slight headache | |Mike Parsons |No | | |None | |Chris Ostrowski |Yes – April 16th |Pending |Pending |None | |Jack Robbins |No | | |None | |

Conclusion – Monday, April 21st

Since the mercury spill last week, your Epi Team has been busy working with the Occupational and Environmental Epidemiology Branch to complete the investigation. Because the exposure time was short, there were no adverse health effects from the mercury spill. Final lab results showed that all students had blood mercury levels below the level of concern (10μg/L). Investigation of the students’ homes and the school bus did not detect high levels of mercury. However, significant time and resources were spent to respond to the spill, decontaminate the area, and investigate possible health effects.

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3 pm- report of mercury spill.

April

April

3 pm- Report of mercury spill.

5 pm- Emergency Management responds to spill.

5 pm- Emergency Management responds to spill.

3 pm- Report of mercury spill.

April

Epi Team interviews students.

5 pm- Emergency Management responds to spill.

Epi Team interviews students.

3 pm- Report of mercury spill.

April

Afternoon- OEE collects air samples.

Afternoon- OEE collects air samples.

Epi Team interviews students.

5 pm- Emergency Management responds $to spill.

3 pm- Report of mercury spill.

April

Media reports on dangers of mercury.

Media reports on dangers of mercury.

Afternoon- OEE collects air samples.

Epi Team interviews students.

5 pm- Emergency Management responds to spill.

3 pm- Report of mercury spill.

April

Epi Team receives lab results.

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