# OAR Box 1128 Prepped byOllie Stewart



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# 45 ) 11-1-22

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TH E INFLUENC E O F ENVIRONMENTA L FACTOR S O NPHYSICA L ' % " ' >. • GROWT H INSCHOO L AGE : ASTUD YO F LO WLEVE L LEAD fpTljfl? , •), ft ^ .!' " EXPOSUR E UJ ] **— ^ v<

T . Lyngbye^' 2 , o.N . Hansen3 , P . Grandjean * 1 Departmen t o f Environmenta l Medicine , Odens e University , Odense , Denmark .

2 Institut e o f Psychiatri c Demography , Psychiatri c Hospital , Aarhus , Denmark . 3 Institut e o f psychology , Universit yo f Aarhus , Aarhus , Denmark . Introductio n Environmenta l factor s hav e long bee nsuspecte d t o play a rol e fo r th e physica l growth . Thi s assumptio ni s base d o n indirec t evidenc e suc ha s th e secula r trend o f increasin g heigh t (1) , difference s o f heigh t withi nth e sam e populatio n and th e influenc e o f socia l clas s o nth e growt h (2) . Th e influenc e o f specifi c environmenta l factor s suc h a s lea d absorptio no r mother s smokin g durin g pregnanc yhav e bee n examine d i nlarg e scal e crossectiona l studie s (3 ) and i n longitudina l studies(2) . Th e curren t Aarhu s study , designe d t o identif yundu e effect s o f earl ylea d exposure , als o evaluat e th e impac t o f social , behavioral , nutritiona l an d medica l factor s a s wel l a s tobacc o smokin g durin g pregnancy . Materia l and method s Acohor t studywit ha neste d case-contro l grou p wa s performe d i n th e Aarhu s municipalit yamon g childre njoinin g th e firs t grad e i n 1982-83 . Collaboratio nwa s obtaine d wit h school s coverin g 82.5 % o f th e populatio ni nal l 2.41 2 children , wh o wer e aske d t o donat e natura l she d deciduou s teet hthroug hth e for mmaster . A t leas t on e toot hwa s recieve d from

130 2 childre n(54%) , wh o wer e representativ e fo r th e tota l cohor t (4) . Th e teet hwer e analyze d fo r thei r

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lea d concentratio n i n th e circumpulpa l denti n(5,6) . Childre nwit ha concentratio n abov e 18. 7 ug/ g wer e selecte d fo r th e cas e grou p and matche d fo r gende r an d socioeconomi c statu s t o a nequivalen t numbe r o f childre nwit hdenti n concentration s belo w5. 0 ug/ g servin g a s contro l grou p (6) . Two-hundre d familie s wer e visite d b yth e pediatricia n o f th e tea m

i nthei r home s an d interviewe d o nth e child s medica l history , dietar yhistory , behavior , tobacc o smokin g o f th e parent s and sociodemographi c factors . Base d o nth e intervie wchildre n wer e exclude d fromfurthe r comparision , i f unsuite d o n accoun t o f medica l ris k factor s fo r impare d growt hand developement . Twent ynin e childre nwer e exclude d fo r medica l reason s (unpublishe d data ) and 1 4 di d no t wan t t o participat e furthe r (4) . Fou r wer e exclude d becaus e o f foreig netni c background . Tw o year s afte r th e intervie wa consen t wa s obtaine d b yletter , fo r informatio n o n growt han d healt hfactor s fro m th e schoo l phycician , from14 5 childre n(7 2 case s and 7 3 controls) . Thes e childre n wer e meassure d (heigh t an d weight ) o n 3 t o 4 occasion s betwee nth e age s o f 6 and 1 0 years . Thes e meassurement s wer e plotte d o ngrowt hcurv e chart s standardize d i na Danis hpopulatio n(1) . Th e growt h o f eac hchil d coul d thu s b e expresse d a s a percentil e fo r length , an d weigh t fo r height , normalise d fo r ag e an d gender . Statistica l analysi s

selecte d variable s wer e analyze d i nrelate d group s an d take nint o individua l multipl e stepwis e analyses . Th e variable s explainin g varianc e a t a p-leve l o f 0. 1 o r les s wer e take n int o a fina l stepwis e regressio nand lea d grou p wa s adde d t o thi s model .

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lengcn . m e onl ysocia l tacto r tna t snowe a associatio nwic n lengt hwa s th e mothe s ag e a t th e birt ho f th e proband , standardize d fo r parity . Thi s variabl e behave d lik e th e medica l variable s and wa s thu s furthe r considere d withi n thi s group . Amon g th e th e nonmedica l factor s (individua l analysis) , "smal l appetite " an d tobacc o smokin g durin g pregnanc ywer e significan t explanator s ( p = 0.0 1 and p = 0.02 ) o f 7 % o f th e variance . Amon g th e medica l factor s (individua l analysis ) cesarea nsec t io n/ youn g ag e o f th e mothe r and previou s abortion s wer e al l significan t a t a p leve l belo w0.0 3 an d explaine d 1 7 % o f th e variance . Whe n

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- medica l variable s an d lead-grou p

Discussio n I t i s know n fro nothe r studie s tha t protei nintak e i s relate d t o growt h(3) . Thi s equivalate s t o th e variabl e "smal l appetite " i n thi s study . Th e variabl e los t it s explanator ypowe r i n th e fina l weighting , an d problal y coul d th e seemingl yassosiatio nb e considere d a consequens e of , rathe r tha na caus e fo r retarde d growt hi nth e presen t population . Th e variabl e cesarea nsectio n i s a nindicato r o f th e medica l factor s tha t lea d t o th e artificia l delivery . Thi s i s i n mos t case s a nindirec t evidenc e fo r placent a incufficiency . Mothers ' tobacc o smokin g durin g pregnanc yha s i n a longitudina l studyexhibite d a dose-respons e patter na s predicto r fo r heigh t a t 7 year s (2) . Th e presen t study replicat e tobacc o a s a predicto r fo r heigh t whil e takin g mor e medica l and environmenta l factor s int o account . Th e lea d effec t i nth e stud yi s foun d i na chil d populatio n wit ha ver yhomogeneou s socia l backgroun d and wit hn o ethni c minorities . Th e notio ntha t th e associatio n i s th e expressio n o f a biologica l effec t i s supporte d by

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t h efindin g o f

lead-grou p a s ariskfacto r fo r learnin g disabilitie s i nth esam ecohor t (unpublishe ddata ) an do f impare dperformanc eb ypsychologica ltestin g (7) . Th e averag ebloo dlea di nth ecohor t wa s belo w 6 0ug/ 1 wholebloo d(unpublishe ddata) , s o i t seem s tha t

eve ni n suc halow-leve llead-pollute darea , earl ylead-absorptio n i s ariskfacto r

fo r impare dlength-growt hi nschoolage . Reference s (1 ) Andersen , E . , Andersen , H . , Hutchins , B . , Nyholm , M. , Peitersen , B . Rosen , J. , Tamdrup , E . & Wichmann , R . Height s a n dweight s i nDanis hschoo lchildre ni n1971-1972 . Ugeskrif t

fo r lager , 136 ; 2796-280 2(1974) . (2 ) Davie , D. , Butler , N . & Goldstein , H . Fro mBirt ht o Seven.Th eSecon dRepor t o f th eNationa lChil dDevelopmen t Stud y(195 8 Cohort).London , Longman , 1907 , p p 8 1-86 . (3 ) Schwartz , J. , Angle , C . , & Pitcher , Betwee nChildhoo dBloo dLea dLevel s Pediatrics , 77 : 281-28 8 (1986) . H . Relationshi p a n dStature . (4 ) Lyngbye , T. , Hansen , O.N . & Grandjean , P . Bia s resultin g fro mnon-participario ni nchildhoo depidemiologi c stuidies : Astud yo f low-leve llea dexposure . Scandinavia n Journa lo f

Socia lMedicine , i npres s (1987) . (5 ) Grandjean , P. , Hansen , O.N . & Lyngbye , K . Analysi s o f lea di ncircumpulpa ldenti no f deciduou s teeth . Annal s o f Clinica lan dLaborator yScience , L4:270-27 5 (1984) . (6 ) Grandjean , P. , Lyngbye , T . & Hansen , O.N . Lea d concentratio nrelate dt o toothtyp ean danalytica l technique . Journa lo f Toxicolog yan dEnvironmenta lHealth , 2 0 : 437-44 5 (1986) . (7 ) Hansen , O.N. , Trillingsgaard , A. , Beese , I. , Lyngbye , T . & Grandjean , P . Neurobehaviora lmethod s i nassessmen t o f childre nwit hlow-leve llead-exposure . Neurobehaviora l Method s i nOccupation. a1 an dEnvironmenta lHealth , Copenhagen , WHO

, Regiona lOffic efo r Europe , 1985 : 183-188 .