Environmental Exposure Surveillance in a Combat Theatre

Environmental Exposure Surveillance in a Combat Theatre

Coleen Baird , MD, MPHColeen Baird , MD, MPH

US Army Center for Health Promotion and Preventive MedicineUS Army Center for Health Promotion and Preventive Medicine

I have no disclosures to make I have no disclosures to make

Range of Exposures in Deployed Range of Exposures in Deployed Settings Settings

• Occupational/Personal Sampling- Individual ExposuresOccupational/Personal Sampling- Individual Exposures

– Actionable for surveillance or otherActionable for surveillance or other

– Archive for general information, document “negative exposure”Archive for general information, document “negative exposure”

• Ambient Sampling: Exposure Not Clearly Linked to an IndividualAmbient Sampling: Exposure Not Clearly Linked to an Individual

– Epidemiological formation of cohortEpidemiological formation of cohort

– Population level risks Population level risks

• Potential Exposures- based on defined “reasonable probability”Potential Exposures- based on defined “reasonable probability”

– May be actionable May be actionable

– May lack sampling informationMay lack sampling information

Air Exposure Concentration Air Exposure Concentration ‘Continuum’‘Continuum’

IDLH TLVs EPA:ambient air standards

mg/m3 ug/m3

Terrorist attack;

accidental releaseindustrial operations;

accidental releases

past practices;

uncontrolled emissions

multiple low-level

exposures, continuous,

long-termSingle exposure

Lifetime exposure

minimal

severesignificant

Refined Exposure AssessmentsRefined Exposure Assessments

• Exposures identifiable to an individual or Exposures identifiable to an individual or Similarly Exposed Groups (SEGs)Similarly Exposed Groups (SEGs)

– Exposed by nature of location or occupation such as Exposed by nature of location or occupation such as asbestos, lead, burning trashasbestos, lead, burning trash

– Requires an exposure assessment and identification of Requires an exposure assessment and identification of group/SEG constituentsgroup/SEG constituents

– Relatively easy to put into medical recordsRelatively easy to put into medical records

– May require individual surveillance May require individual surveillance

Ambient or Routine ExposuresAmbient or Routine Exposures

• Greater likelihood of being “low”Greater likelihood of being “low”

• Lower likelihood of health effectsLower likelihood of health effects

• Cohorts more readily “defined” thru available data Cohorts more readily “defined” thru available data sourcessources

• Exposures to those in defined cohort more Exposures to those in defined cohort more variablevariable

Ambient Environmental Monitoring Ambient Environmental Monitoring

• Air: PM/metals/volatile organics in the ambient environment of the Air: PM/metals/volatile organics in the ambient environment of the samplersampler

– PM levels high, but variablePM levels high, but variable

– Most other findings rareMost other findings rare

• Large population at risk/Base camp levelLarge population at risk/Base camp level

• Exposures not uniformExposures not uniform

– Movement Movement

– Distance from samplerDistance from sampler

– IndoorsIndoors

– Convoys/Trash Convoys/Trash

Ambient Environmental Monitoring Ambient Environmental Monitoring

Challenges linking location data (population at Challenges linking location data (population at risk) to health datarisk) to health data

Outcomes may be diluted due to misclassification Outcomes may be diluted due to misclassification of exposure, non-specific outcomesof exposure, non-specific outcomes

Data not readily interpretable by most providersData not readily interpretable by most providers

Incident or Unplanned EventsIncident or Unplanned Events

• Greater likelihood of being “high”Greater likelihood of being “high”

• Greater likelihood of health effectsGreater likelihood of health effects

• Lower likelihood of actual measurementLower likelihood of actual measurement

• Typically involve fixed but hard to define cohortTypically involve fixed but hard to define cohort

Principles of Medical Surveillance Principles of Medical Surveillance Under the NRPUnder the NRP

• Maintain the physical and mental health of Maintain the physical and mental health of responders/Identify new clinical entities/Assess responders/Identify new clinical entities/Assess adequacy of PPEadequacy of PPE

• Participation should be confidential and voluntaryParticipation should be confidential and voluntary

• There should be a centralized mechanism to There should be a centralized mechanism to capture data related to individual and collective capture data related to individual and collective exposuresexposures

Principles of Medical Surveillance Principles of Medical Surveillance Under the NRPUnder the NRP

• Creation of a registry of workers at the siteCreation of a registry of workers at the site

• Exposure assessment strategies should be Exposure assessment strategies should be developed and implemented to protect workers developed and implemented to protect workers and guide interventionsand guide interventions

• Each individual should receive detailed and Each individual should receive detailed and interpreted biomedical and exposure datainterpreted biomedical and exposure data

• Risk communication needs to be an integral part Risk communication needs to be an integral part

Enhanced exposure analysesEnhanced exposure analyses

UNCLASSIFIED

2003 Sulfur Fire 2003 Sulfur Fire

• Multiple samples taken over weeks at various Multiple samples taken over weeks at various locations*locations*

• Health care provided on site by a special team*Health care provided on site by a special team*

• Documented in medical record*Documented in medical record*

• Exit physical standardized for firefightersExit physical standardized for firefighters

• Roster of firefighters obtained and archived*Roster of firefighters obtained and archived*

• Health outcome analysis*Health outcome analysis*

Long Term Follow-up Long Term Follow-up

• Defined cohort Defined cohort

– Small numbersSmall numbers

• Poorly defined cohortPoorly defined cohort

– Exposures variableExposures variable

– Weak exposure/ weak inclusionWeak exposure/ weak inclusion

» Misclassification biasMisclassification bias

» Rare outcomes/unusual coding Rare outcomes/unusual coding

Lessons LearnedLessons Learned• Traditional IH surveillance possible in deployed Traditional IH surveillance possible in deployed

setting if equipment/skill sets availablesetting if equipment/skill sets available

• Ambient sampling has proven difficult to integrate Ambient sampling has proven difficult to integrate into routine medical careinto routine medical care

• ““Incident driven” events pose a challenge for data Incident driven” events pose a challenge for data collection, and potentially for long-term follow-upcollection, and potentially for long-term follow-up