Luik III: follow-up study

Neurobehavioural and cognitive effects of prenatal exposure to persistent

environmental toxicants in three year old children (2002-2007):

Preliminary results

Griet VermeirProf. Dr. M. K. Viaene

Slide 2

Overview

Introduction

Goals

Methodology

Results

Discussion & Conclusion

Slide 3

Introduction

Several studies (Ribos-Fito et al., 2001; Struempler et al., 1985, Feldman, 1999; Burns et al., 1999; Patandin et al., 1999; …):

neurobehavioural developmentin young children

PCBs and heavy metals

neg.effect

Slide 4

Goals:

The present study is part of the Environmental Health Action Program (2001-2006) in Flanders.

=> Cohort “neurological development” (sept 2002-march 2007).

Effects of prenatal exposure to heavy metals (Pb, Cd) and PCBs and dioxine-like compounds on neurobehavioural and cognitive development in young children.

Subgroups at risk (gender, low premorbid IQ, no breastfeeding)? (partial data only available till now)

Interactive effects of co-exposures to different chemicals?

Behaviour: a useful bio-effect parameter in follow-up studies in populations exposed to toxic agents?

Slide 5

Method

Based on inclusion criteria, the study group consisted of 200 participants (baby-mother pairs). These babies were followed until they reached the age of 3 years.

Data:

Prenatal exposure

(Postnatal exposure)

Questionnaires: concerning mother and child

Cognitive and neurobehavioural examination

Covariates (HOME,SES,family structure,intelligence mother,…)

Slide 6

Inclusion criteria

Participant biomonitoring study in Flanders Pregnancy without complications born at term (>36 weeks) no major congenital abnormalities or diseases no twins no abnormal or asymmetrical reflexes during

standard neurological screening during the first days

Flemish as their mother-tongue Written informed consent

Slide 7

Exposure parameters

Prenatal exposure in cord blood:

Cd Pb PCBs (PCB 118, 170 and 28, 52, 101, 138, 153,

180) Dioxin-like compounds (CALUX-TEQ) HCB DDE

(Postnatal exposure: estimates from repetitive food intake questionnaire First year: monthly Second year: three-monthly)

Slide 8

Test Measurement type Time of assessment

Snijders-Oomen non-verbal intelligence test (SON-R 2.5-7)

Intelligence: reasoning and visuo-spatial abilities

36 months

Bayley Scales of Infant Development (BSID-II-NL)

cognitive development: results in mental and motor indices

36 months

Reynell Language Developmental Scale (RTOS)

receptive language development level measured by oral instructions to carry out small tasks while playing with toys

36 months

NES 3 (neurobehavioural evaluation system) Continuous Performance Test

Computerised vigilance task (adapted for children by GV)

36 months

Questionnaires/observation Measurement type Time of assessment

Milestones Skills and abilities 0-36 months

Infant behaviour Questionnaire (IBQ) Temperament as observed by the mother 12 months and 24 months

Child behaviour Checklist (CBCL) & Caregiver-Teacher’s Report Form (C-TRF)

Functioning of the children as perceived by the mother and the teacher/kindergarten.

24 and 36 months

Child Sexual behaviour Inventory (CSBI) Sexual behaviour as observed by the mother

36 months

PSAI (PreSchool Activity Inventory) Play behaviour (masculine/feminine) 36 months

Observation of toy preference 7 min. lasting observation of masculine/feminine play behaviour

36 months

Tests and questionnaires concerning children

Slide 9

Test and questionnaires concerning mother

Test Goal Time of assessment

WASI Intelligence estimate(verbal & performal)

36 months

State Trait Anxiety Inventory (STAI)

Anxiety: neuroticism, depression

12, 24 & 36 months

Perceived Stress Scale

Stress-measurement 12, 24 & 36 months

Life-events important events in last year

12, 24 & 36 months

NEO-PI-R Personality 36 months

Slide 10

Covariates (1)

General information– Gender– Season of birth

Information family: – family structure, – parity, socio-economic state, – Observation home environment (HOME-score)

General health of the child:– weight, – length, – Apgar score, – medical history, – breastfeeding

Test procedures:– Age of child at testing– Test leader

Slide 11

Covariates (2)

Data on mother:– age, – highest education level, – intelligence estimate, – complications during pregnancy, – medication during pregnancy and labour, – STAI: anxiety mother, – smoking, alcohol and drug use during pregnancy

Cortisol as fysiological stress parameter Saliva samples (Salivette)

– beginning and end of the first test session from mother and child

– the day before the second test session (just after awakening, 30 minutes after awakening, at 1 pm and 30 minutes before going to sleep).

Slide 12

Overview measurements and examinations

Cord blood(Pb, Cd, PCB’s, dioxines,TSH,FT3, FT4),feeding

information,covariates

12 months 24 months

Monthly questionnaire food intake and development

Three-monthly questionnaire food intake and development

Information pregnancy,Postnatal depression

Behaviour child,emotional status mother,

life-events

Cognitive andNeurobehavioural examination

child, testing mother,observation home

EnvironmentCortisol

36 months0 months 1 month

Slide 13

Selected regions

Regions participants

Non ferrous smelter 68

Harbor 80

Rural area 48

Household combustion incinerators

10

TOTAAL 206

Slide 14

Data collection is still ongoing: until March 2007.

Data on first 102 participants: preliminary results

Not all variables processed/available: (Postnatal exposure estimates)

Cortisol as covariate

Quality control of the general questionnaire of the Environmental Health Action Program

Practical issues

Slide 15

Results

All analyses were done in SPSS 12.0

Distribution outcome variables: no transformations needed

No test leader effects (ANCOVA, p>0,100)

Stepwise lineair regression

Slide 16

Group characteristics (1)

Total groupN=1021

Minimum Maximum MeanStd.

ErrorStd.

Deviation 

Age Child at testing BSID (weeks) 154 179 159,99 ,467 4,715  

Age Child at testing RTOS (weeks) 155 181 161,76 ,502 5,046  

Age Mother at birth child 20,27 41,5529,476

2,40868 4,10722  

Parity 1,00 4,00 1,5294 ,08089 ,81697  

Duration of Pregnancy 36,00 42,0039,405

9,11872 1,19313  

Total weeks of breastfeeding 0 104 16,19 2,003 19,934  

Number of weeks only breastfeeding (n=53)

2 32 13,42 ,941 6,854  

Number of infections during Pregnancy

,00 3,00 ,4059 ,07200 ,72358  

Neuroticism scale Mother (NEO-Nn) 92 184 135,95 2,390 21,510  

STAI Mother (trait) 20 57 35,13 1,078 9,58  

Verbal IQ mother (WASI) 78 136 102,40 1,270 12,705  

Performance IQ moeder (WASI) 70 140 102,67 1,330 13,234  

Total IQ mother (WASI) 75 136 102,61 1,224 12,236  

BMI mother 16,14 40,3922,952

6,36610 3,62422  

BMI child 1 2,06 1,374 ,0145 ,1453  

Slide 17

Group characterictics (2)

Total groupN=1021

Minimum Maximum Mean Std. ErrorStd.

Deviation 

SumPCB/total lipid conc* 4,01 271,81 89,7815 6,39938 63,99378  

CaluxTEQ/total lipid conc 5,05 123,49 26,7751 2,43896 20,55104  

DDE-conc/total lipid conc 25,000 878,378 194,48970 17,100572 172,707307  

HCB-conc/total lipid conc 2,3 132,1 29,929 2,3781 23,1791  

Pb-conc Umbilical Cord Blood(µg/L)

1,000 66,374 19,17382 1,384813 13,638831  

Cd-conc Umbilical Cord Blood(µg/L)

,045 2,687 ,40258 ,049677 ,489260  

Fe-conc Umbilical Cord Blood 233159,68 899797,80590266,79

5711306,025

43110775,9732

7 

Cu-conc Umbilical Cord Blood

337,12 1601,41 622,0510 17,85759 174,96792  

Zn-conc Umbilical Cord Blood 474,54 30000,00 2096,1357 309,65401 3033,97730  

FT3 Umbilical Cord Blood# ,60 7,45 1,5945 ,09762 ,96637  

FT4 Umbilical Cord Blood# ,85 4,30 1,3383 ,05477 ,54496  

TSH (heel prick) 1,920 39,790 8,37443 ,620446 6,235403  

Total lipid conc Umbilical Cord Blood

74,000 514,894 218,18322 7,873472 79,127416  

Tabel 2: group characteristics1 CaluxTEQ-values were available only in n=71 and questionnaires of the results NEO-FFI were available in n=81 and of the STAI in n=79.*SumPCB= PCB 138+ PCB 153+ PCB 180# Thyroid function

Slide 18

Results analyses

FT3, FT4 & TSH

PCBs & CALUX:

sum PCB

CALUX-TEQ

Heavy metals: Pb

(Pesticides: HCB & DDE)

Slide 19

Pollutant

(µg/L)

Log ft4 (ng/dl) Log ft3 (pg/ml) Log TSH (mIU/L)

β p β p β p

PCB 118 -0.318 < 0.0001 -0.192 0.010 -0.087 0.261

PCB 138 -0.392 < 0.00001 -0.235 0.004 -0.158 0.063

PCB 153 -0.176 0.041 -0.083 0.327 -0.050 0.567

PCB 170 -0.346 < 0.0001 -0.192 0.022 -0.101 0.242

PCB 180 -0.332 < 0.001 -0.248 0.004 -0.058 0.522

Calux TEQ -0.165 0.038 -0.154 0.043 -0.018 0.830

HCB -0.270 < 0.001 -0.151 0.052 -0.108 0.179

p,p’-DDE -0.169 0.018 -0.104 0.137 -0.042 0.569

Zn +0.277 0.0001 +0.185 0.008 +0.005 0.940

Multiple linear regression - Adjusted for total lipids, age mother, sex, gestational age, and alcohol consumption (n ≥ 182)

Cord blood - Relationship pollutants & THs(preliminary results, in collaboration with

Johan Maervoet, UIA)

Slide 20

RESULTS

FT3, FT4 & TSH

PCBs & CALUX: sum PCB CALUX-TEQ

Heavy metals: Pb

(Pesticides: HCB & DDE)

Slide 21

Milestones

Milestones(0-36 months)

Sum PCB Other significant covariates

(n=73) B SE (B)

Beta p-value Beta p-value

crawling* 0,007 0,003 0,250 0,0300 seizoen -0,365 0,003

First steps alone* 0,017 0,007 0,402 0,0140 -

* significance does not change with STAI in the model

Slide 22

Infant behaviour at 12 months

IBQ (12 months) Sum PCB Other significant covariates  

(n=85) B SE (B) Beta p-value Beta p-value

Soothability* 0,004 0,002 0,254 0,042 -

significance does not change after correction for STAI

The IBQ on 24 months did not show any significant results

Slide 23

BSID: mental & motor scales

Bayley (BSID)# sumPCB Other significant covariates

B SE (B) Beta p-value Beta p-value

Mental Scale° 1 -0,069 0,034 -0,219 0,044 -

Motor Scale >0,100 Gender (F>M) 0,251 0,026

# values corrected for age at time of testing° significance does not change after correction for STAINone of the other PCB exposure parameters, Calux TEQ, DDE, HCB and Cd concentration reached (borderline) statistical significance (all p>0,1)1 in ANCOVA analysis the relation is borderline significant in the girls group (partial eta= 0,086; p= 0,053) but not in the boys (partial eta= 0,004, p>0,100).

Slide 24

Observation toy preference

Observation Toy Preference

SumPCB Other significant covariates

 

Boys

(n=34) B SE (B) Beta p-value Beta p-value

% Masculine play behaviour*

-0,205 0,082 -0,471

0,020 -

Switching toys (number)*

-0,019 0,009 -0,286

0,038 -

% Non-gender specific* 0,140 0,042 0,421 0,003 BreastfeedingAsfyxiaParity

0,833-0,537-0,553

0,0000,0000,000

* significance does not change after correction for STAI

In girls, no effects of any of the exposure parameters were found on toy preference.

Slide 25

Child behaviour Checklist

CBCL (36 months)

Sum PCB Other significant covariates

(n=56) B SE (B) Beta p-value Beta p-value

Affective problems* -0,009 0,003 -0,371 0,006 STAI 0,490 0,000

* significance does not change after correction for STAI

CBCL 24: no effect.

Slide 26

Child behaviour Checklist

CBCL(36 months)

Calux TEQ Other significant covariates

(n=56) B SE (B)

Beta p-value Beta p-value

Sleeping problems -0,073 0,034 -0,341 0,043 TIQ mother -0,454 0,009

Emotionally Reactive -0,085 0,036 -0,417 0,024 -

Slide 27

BSID: interaction sumPCB*Pb

Bayley (BSID)# SumPCB*PB Other significant covariates

B SE (B) Beta p-value Beta p-value

Mental Scale° 1 -0,004 0,002 -0,282 0,011 -

Motor Scale 2 >0,100 Gender (F>M)

0,251 0,026

values corrected for age at time of testing° significance does not change after correction for STAI1 in ANCOVA analysis, the relation is borderline significant in the girls group (partial eta= 0,081; p= 0,065) but not in the boys (partial eta= 0,006, p>0,100).2 in ANCOVA analysis, the relation is borderline significant in the girls group (partial eta= 0,088; p= 0,057) but not in the boys (partial eta= 0,038, p>0,100).

Slide 28

CBCL: interaction effect

CBCL(36 months)

Sum PCB*Pb Other significant covariates

(n=56) B SE (B) Beta p-value Beta p-value

Affective problems* -0,000 0,000 -0,355 0,015 STAI SmokingParityHome

0,3060,543-0,6420,327

0,0200,0000,0000,013

* significance does not change after correction for STAI

Slide 29

Summary PCBs & CALUX (1)

Sum PCB:

Lower score on Mental Development Index (BSID)

More masculin play behaviour, less gender-specific behaviour (Boys only)

Less affective problems Easier to sooth at 12 months Crawling & First Steps Alone at later age

Slide 30

Summary PCBs & CALUX (2)

CALUX-TEQ:

less sleeping problems less emotional reactivity

Interaction sumPCB*PB has surplus effect:

On BSID: even lower Mental Development Index (Girls might be more vulnerable)

(On BSID: Motor Development Index: Girls might be more vulnerable)

On CBCL: even less affective problems

Slide 31

RESULTS

FT3, FT4 & TSH

PCBs & CALUX: sum PCB CALUX-TEQ

Heavy metals: Pb

(Pesticides: HCB & DDE)

Slide 32

Milestones

Milestones(0-36 months)

PbUCB Other significant covariates

(n=73) B SE (B)

Beta p-value Beta p-value

pulling oneself up* 0,001 0,000 0,393 0,001 -

* significance does not change with STAI in the model

Slide 33

Infant behaviour

IBQ (12 months) PbUCB Other significant covariates

(n=85) B SE (B) Beta p-value Beta p-value

Soothability p>0,100

Activity level* 0,018

0,007 0,321 0,012 -

* significance does not change with STAI in the model

IBQ (24 months) PbUCB Other significant covariates

(n=56) B SE (B) Beta p-value Beta p-value

Duration of orienting* -0,027 0,012 -0,334 0,029 -

Slide 34

SON IQ

SON PbUCB Other significant covariates

B SE (B) Beta p-value Beta p-value

 

SON total IQ* -0,259 0,102 -0,235 0,013 Gender (F>M)

0,407 0,000

 

SON Reasoning IQ* -0,002 0,001 -0,228 0,017 Gender (F>M)BMI childHOME

0,413

0,2540,202

0,001

0,0100,035  

SON Performance IQ* - - -0,213 0,056 Gender (F>M)

0,318 0,002

 

* significance does not change after correction for STAINone of the PCB exposure parameters, Calux TEQ, DDE, HCB, and Cd concentration reached (borderline) statistical significance (all p>0,1)

Slide 35

Mother-child interaction

Mother/child interaction (Erikson sensitivity scales)

PbUCB Other significant covariates

(n=63) B SE (B) Beta p-value Beta p-value

Structure and limit setting -0,037 0,014 -0,327 0,009 -

Slide 36

SON IQ: interaction effects

SON PbUCB*sumPCB Other significant covariates

B SE (B)

Beta p-value Beta p-value

SON total IQ* 1 -0,002 0,001 -0,224 0,018 Gender (F>M)Home

0,374

0,231

0,000

0,017

SON Reasoning IQ* 1 -0,265 0,094 -0,265 0,006 Gender (F>M)BMI childParity

0,432

0,2320,265

0,000

0,0150,006

SON Performance IQ* - - 0,056 Gender (F>M)

0,286 0,015

* significance does not change after correction for STAI in ANCOVA analysis, the relation is not significant in boys or girls separately.

Slide 37

Summary Pb & Cd

Lower intelligence (SON-IQ): Total IQ Reasoning IQ

SON-IQ: Pb*sum PCB

Mother-child interaction: More difficult to give structure and set limits?

IBQ 12 months: higher activity level

IBQ 24 months: decreased duration of orienting (sustained attention)

Milestones: pulling oneself up later?

Slide 38

Other exposure parameters

• No significant effects were found with Cd.

• No relation was found between sumPCB, Calux TEQ, Cd.

Slide 39

Other outcome variables

PSAI: not analysed due to interpretation problems of the official scoring system

GBO and RTOS= no relation with any of the exposure parameters

Slide 40

Conclusion (1)

Effects of prenatal exposure to heavy metals (Pb) and PCBs and dioxine-like compounds on neurobehavioural and cognitive development in young children: Pb: reproduction from literature PCBs:

– developmental index (BSID)=> reproduction literature– gender-specificity => relatively new (suggested in literature)

Subgroups at risk: only partial data available Gender-effects that were suggested:

– Gender specificity– IQ-related (comprehension & reasoning) (partial data only available till now)?

Knowing that PCBs are endocrine disruptors, this isn’t surprising. Interference of sex-hormones prenatally might have different effects in boys and girls. As a consequence, the cognitive functions will develop in a different way.

Slide 41

Conclusion (2)

Interactive effects of co-exposures to different chemicals? Structurally different chemicals might have a

more pronounced effect (on IQ) in co-exposure

Behaviour: a useful bio-effect parameter in follow-up studies in populations exposed to toxic agents: Gender specific behaviour: very stable parameter

and relatively easy to obtain.

Slide 42

Collaborators

Openbaar Psychiatrisch Ziekenhuis– Prof. Dr. M.K. Viaene– Lic. Psych Griet Vermeir– Rita Verachtert– Mieke Thijs– Jan Laenen– Natalie Verelst

KULeuven, Faculteit Psychologie– Prof. B. Van Den Bergh– Ine Nijs– Lien Van Laer– Veerle Nullens

UIA, Department Pharmaceutical sciences – Prof. A. Covaci– Lic Pharm Johan Maervoet

UGent, Radiotherapy and Nuclear Medicine– Prof. Dr. N. Van Laerebeke– Joan Govaerts

All collaborators of Environmental Health Action Program