TheGirasoles(Sunflower)Study:ExploringthePhysiologicHeatStressResponse

LindaMcCauley,RN,PhD,FAAN,FAAOHNDeanandProfessor

NellHodgsonWoodruffSchoolofNursingEmoryUniversity

Friday,October26,2018

TheGirasoles(Sunflower)Study

CenterforDiseaseControlandPrevention|NationalInstituteforOccupationalSafetyandHealth2014-18R01-OH01657-01

OccupationalHeatStress

TheMoultrieObserver

NaplesDailyNews

1.  Hazard2.  Vulnerabilityfactors:

•  Workplaceexposure•  Sensitivity(non-modifiable)•  Adaptivecapacity(modifiable)

3. HeatStressResponse

FarmworkerVulnerabilitytoHeatHazardsFramework

Mac,ValerieViThien,andLindaA.McCauley."Farmworkervulnerabilitytoheathazards:aconceptualframework."Journalofnursingscholarship49.6(2017):617-624.

5GirasolesStudyRecruitmentLocationsinFlorida Pierson

ApopkaFellsmereImmokaleeHomestead

RecommendedCoreBodyTemperatureLimits

38.0°C(100.4°F)–Forworkersnotacclimatizedormedicallycleared.38.5°C(101.3°F)–Forworkersacclimatized,medicallyscreenedandmonitored.Workercorebodytemperatureshouldneverexceedthislevel.

3WorkdaysofBiomonitoring+SurveysBaseline,Pre-WorkdayandPost-WorkdayBiologicalSamples:-  UrineSpecificGravity-  Bloodosmolality/Bloodchemistry

Survey:-  Heat-relatedIllness

Symptoms-  Demographics

ComprehensiveHeatStressMonitoringActigraphAccelerometerrecordsphysicalactivity

Heartratemonitormeasuresheartrateatwork

CorTemp®monitorrecordscorebodytemperature

Homemonitorrecordstheovernighthometemperatures

iButtonrecordsthetemperatureandhumidityatyourworkplace

Hazard:EnvironmentalHeatStress

EnvironmentalHeat•  FAWNData:

•  RegionalWeatherNetworkDataevery15minutes•  MeanHeatIndex:90°F±6

•  iButtonData•  Immokalee(n=66)andApopka(n=39)•  284Observationdays•  Worksite-baseddataevery15minutes=10,000readings•  MeanHeatIndex:105°F±9.2

MacVV,HertzbergV,McCauleyLA.ExaminingAgriculturalWorkplaceMicroandMacroclimateDataUsingDecisionTreeAnalysistoDetermineHeatIllnessRisk.JournalofOccupationalandEnvironmentalMedicine,inpress,October2018.

Vulnerability

StudyParticipantCharacteristicsn=248

•  MeanAge:38years(SD±9)•  Female:62%•  YearsinU.S.Agriculture:12years(SD±8)•  CountryofOrigin:Mexico(66%),Guatemala(15%),Haiti(10%),Other(7%),U.S.(2%)

• WorkType:Crops(31%),Fernery(26%)andNursery(41%)

MeasuredWorkActivity:Accelerometer•  Accelerometerwasplacedattheworker’srightiliaccrestand

recordedaccelerationcountsonthreeplanesofmotion(vertical,antero-posterior,andmedio-lateral)every30secondsduringtheworkday

•  Vectormagnitude(VM3):acompositeactivitycountmeasureincorporatingallthreeplanesofmotion

•  Timespentinmoderatetovigorousactivity(MV):calculatedbysummingtheminutesreachingaVM3countof≥26901

1SasakiJE,JohnD,FreedsonPS.ValidationandcomparisonofActiGraphactivitymonitors.JSciMedSport.2011;14(5):411-6.doi:10.1016/j.jsams.2011.04.003.PubMedPMID:21616714.

ActivityMeasuresfromAccelerometerData

ProportionofDaySpentinActivityLevels

ActivityPatternOvertheWorkday

HydrationStatus•  Urinesamplescollectedbeforeworkandafterworkfromeachparticipant

•  UrineSpecificGravity(USG):measurementwidelyusedtomeasurehydrationstatusinthefieldsetting– Valuesrangefrom1.000(purewater)to1.050(maximumconcentrationcapacityofrenalsystem

•  USGwascategorizedinto– USG≥1.020:hypohydrationthreshold– USG≥1.030:clinicalindicatorforseveredehydration

USGmeasuresbeforeandafterwork

PlotsdisplayUSGmeasuresforn=248workers,over549workdays

HydrationStatus(n=248,549workdays)

Biomarker Before Work1 After Work1

p value2

USG, mean ± SE 1.020 ± 0.0004 1.024 ± 0.0004 <.0001

USG ≥ 1.020 53% 81% <.0001

USG > 1.030 3% 13% <.0001

1nparticipantsforday1wasn=248,day2wasn=243,andday3wasn=2282adjustedforrandomeffectsduetomultipleparticipantsinhouseholdsandmultipledaysperparticipant

Mix,J.,Elon,L.,ViThienMac,V.,Flocks,J.,Economos,E.,Tovar-Aguilar,A.J.,StoverHertzberg,V.andMcCauley,L.A.,2018.HydrationStatus,KidneyFunction,andKidneyInjuryinFloridaAgriculturalWorkers.Journalofoccupationalandenvironmentalmedicine,60(5),pp.e253-e260.

Response

HeatRelatedIllnessSymptoms•  Onthepost-worksurvey,workersreportedHRIsymptomsexperiencedduringtheirworkday:–  Excessivesweating–  Headache–  Dizziness–  Nausea/Vomiting– MuscleCramps–  Confusion–  Fainting

•  84.3%ofworkersreportedatleastonesymptom,42.3%reportedtwoormoresymptoms,and18.6%reportedthreeormore

Heat-RelatedIllnessSymptomsDuringWork

71%

42%

19% 15% 14% 9% 5%EXCESSIVESWEATING

HEADACHE DIZZINESS NAUSEAORVOMITING

MUSCLECRAMPS

CONFUSION FAINTING

Mutic,A.D.,Mix,J.M.,Elon,L.,Mutic,N.J.,Economos,J.,Flocks,J.,Tovar-Aguilar,A.J.andMcCauley,L.A.,2018.ClassificationofHeat-RelatedIllnessSymptomsAmongFloridaFarmworkers.Journalofnursingscholarship,50(1),pp.74-82.

BodyTemperature&HeartRateinOneWorker-  Recordedevery30seconds-  2consecutivereadingsover38.0Cor38.5Cconsideredexceedingphysiologiclimitthreshold

-  TemperatureorHeartRatefileremovedif>20%ofdatapointsmissing

MethodsforAnalyzingReal-TimeData

CoreTemperatures2015-2017

82%reached38.0°CLengthoftimeover38.0°CMedian=69minutesRange=1-555minutes

24%reached38.5°CLengthoftimeover38.5°CMedian=22minutesRange=1-318minutes

HeartRate2015-2017%WorkerswithaMeanWorkdayHeartRate(HR)>115bpm

(35%ofMaximumAerobicCapacity)on≥1StudyDay0

20

40

60

80

100

MeanHR≥115bpm

MeanHR<115bpm

79.4%

20.6%

WhatVulnerabilityFactorsPredicttheHeatResponse?

•  HydrationStatus•  WorkIntensity•  Gender,Age,BMI•  MedicalConditions•  BreaksandShade

PhysiologicResponsetoHeat:CoreTemperature>=38°C

SignificantRiskFactors: ChangeinoddsofT≥38 95%CI

ModelconsideredWorkIntensity Per10MinutesMod/VigActivity 5%increase 2%-8%Per1unitBMI 7%increase 1%-13%Per5°FMeanHeatIndex 27%increase 4%-56% ModelconsideredDehydration Per.010UrineSpecificGravityinpm 47% increase 8%-101%Per1unitBMI 6%increase 1%-12%Per5°FMeanHeatIndex 26%increase 3%-54%

PhysiologicResponsetoHeat:CoreTemperature>=38.5°C

SignificantRiskFactors:

ChangeinoddsofT≥38.5 95%CIModelconsideredWorkIntensity Per10MinutesMod/VigActivity 4%increase 0%-7%Per1yearWorkinginAgriculture 8% decrease (-13)%-(-3)%Per1unitBMI 17%increase 7%-27%Per5°FMeanHeatIndex 39%increase 2%-89%Male(comparedtoFemale) 142% increase 20%-386%ModelconsideredDehydration DehydrationwasnotasignificantpredictorofT≥38.5;otherresultssimilar

HeatExposureandKidneyFunction

KidneyFunction:2015-2016Biomarker Before Work1 After Work1

p value2

Serum Creatinine, mean 0.70 ± 0.13 0.80 ± 0.013 <.0001

eGFR, mean 115.2 ± 0.94 104.7 ± 0.94 <.0001

eGFR <90 3% 20% <.0001

BUN, mean 14.4 ± 0.29 15.8 ± 0.29 <.0001

Serum Potassium, mean 4.4 ± 0.02 4.2 ± 0.02 <.0001

Serum Sodium, mean 141.0 ± 0.11 141.2 ± 0.11 .01 1nparticipantsforday1wasn=248,day2wasn=243,andday3wasn=2282adjustedforrandomeffectsduetomultipleparticipantsinhouseholdsandmultipledaysperparticipant

ChronicKidneyDiseaseofUnknownEtiology(CKDu)

•  Affecting agricultural workers around the globe •  Mainly sugar cane industry •  Primarily young men in seemingly good health •  Need for dialysis in 30’s and 40’s •  > 20,000 premature deaths in Central America alone •  California Heat Illness Prevention Study (CHIPS) (n=295)

–  12% with acute kidney injury over the course of one day at work

AKIinGirasolesPresenceofAKI:•  36%ofparticipantshadthecriteriaindicatingAKIonatleastoneworkdayStagesofAKI:•  32%hadstage1AKIonatleastoneworkday•  3%hadstage2AKIonatleastoneworkday•  0.4%hadstage3AKIonatleastoneworkday•  TheoddsofAKIincreased22%foreach5bpmincreaseinmeanheartrateand37%foreach

5degree(°F)increaseinmeanheatindex(KIDIGOCriteria:Increaseofpost-shiftserumcreatininebyatleast0.3mg/dLOR≥1.5timesthepre-shiftcreatinine)

Analyses/PapersinProgress•  PredictorsforHeatStressSymptomsandCoreBodyTemperatures

•  OverallHealthStatusandWorkBehaviorsasPredictorsofHeatResponse

•  QuantifyingOccupationalWorkIntensityandHeatStressResponse

•  SeasonalDifferencesinWorkIntensityandHeatStressResponse

****CommunityTranslationofResearchFindings*****

NextSteps

•  Pilottestinginterventionstoreduceheatrelatedillness•  Metabolomicanalysisofworkerswithheatexposure•  Heatexposureandthemicrobiome

Acknowledgements•  FarmworkersAssociationofFlorida

–  JeannieEconomos–  AntonioTovar-Aguilar,PhD–  NezahualcoyotlXiuhtecutli,MS

•  UniversityofFlorida–  JoanFlocks,JD

•  EmoryUniversity–  RoxanaChicas,BSN,RN–  LisaElon,MS–  VickiHertzberg,PhD,FASA,P.Stat–  ValerieMac,PhD,RN–  JacquelineMix,PhD,MPH–  AbbyMutic,MSN–  NathanMutic,MS,MAT,M.Ed–  EstefaniIgnacio,BS

•  Funders–  NIOSHR01OH010657–  NIOSHR21OH009830-01

Thankyou!