ATVRES

Artificial Christmas Trees: How RealAre the Lead Exposure Risks?

Richard P. M.ids, I'li.n.Stcvra C. Patch, Ph.D.

Tamara J. Pandolio

Abstract Exposure to lead has long been recognized as a major publichealth issue in the United States and other industrialized na-

tions. The health risks associated with low lead levels mean that consumer products (suchas those made from polyiiuyl chloride |PVC| plastic, which often incorporates lead asa stahilizer) with even moderate lead exposure risks could he dangerous. The purposeof the experiments reported in this article was to test for lead exposure from artificialChristmas trees made of PVC, which are now present in an estimated 50 million U.S.households. The first phase of experimentation tested artificial Christmas trees in thelahoratory for lead content in branches, lead transfer from hand contact, and lead dustlevels under the tree. The second phase was based on a field-testing sur\ey of house-holds with artificial Christmas trees. Results from these experiments show that, whilethe average artificial Christmas tree does not present a significant exposure risk, inthe worst-case scenarios a suhstantial health risk to young children is quite possible.

IntrodurtionL.xposure lo lead has long been recognized as amajor public heallh issue in the United Statesand other industrialized nations. During thelate 1980s and early 1990s, it was discoveredthat lead would cause permanent and irrevers-ible neurological damage, especially in infantsand young children, at far lower exposure lev-els than previously believed (McMichael et al.,1988; Sciarillo, Alexander, & Farrell, 1992).Although recent data show that baseline bloodlead levels have been declining over the lasttwo decades (Mattuck, Beck, Bowers, & Co-hen, 2001), lead is still a significant threat tohealth, particularly in children.

A recent study involving multivariate analy-sis of 4,853 study subjects ranging in age from6 to 16 years found reductions in cognitive

performance associated with blood lead levelsas low as 2.5 micrograms per deciliter (pg/dL)(l^nphear, Dietrich, Auinger, & Cox, 2001).Thus, lead-containing products with even mod-erate potential to cause human exposure arebecoming recognized as having public healthsignificance. One particular study found thateven children whose blood lead levels (BLLs)never exceeded the Centers for Disease Con-trol and Prevention (CDC) level of concern (10pg/dL) could have decreases in lQ of 2.6 pointsper 10 pg'dL increase in BLLs (Winter, 2001).In the most recent study of the neurological ef-fects of low-level lead exposure, Canfield andco-authors (2003) found a 7.4-point IQ deficit(with a 95 percent confidence interval of 3.2-12.9 points, as measured hy the Stanlord-BinctIntelligence Scale and the Revised Wechsler

Preschool and Prinnary Scale of Intelligence) asBLLs increased from I to 10 M^dL. This find-ing strongly suggests that neurological damagemay be caused at even lower BLLs. This lateststudy, which tested 172 children ranging in agefrom six months to five years and measurednine confounding lactors, further underscoresthe importance of identifying and addressingeven relatively small lead exposure concerns.

Several meta-analyses have been done tofurther investigate the connection betweenBLLs and IQ deficits. Some researchers(Kaufman, 2001; Pocock, Smith, &Baghurst,1994) suggest that although there is someevidence that supports the connection, otherexplanations need considering before defini-tive conclusions can be drawn on the subject.These researchers fear ihat recent sludieshave not adequately allowed ior confoundingfactors and that other shortcomings in thestudies may lead to improper conclusions.Other researchers (Needleman & Bellinger,2001) argue that meta-ana!ysis shows thailead does indeed have a negative impact onIQ, even when multiple variables have beencontrolled for in different statistical models.

In addition to intellectual effects, studieshave connected lead exposure with behavior-al and emotional problems, such as aggressiveor anxious behavior, in children (Burns, Ba-ghurst. Sawyer, McMichael, &r Tong, 1999).Lead may also affect the growth of children,as was documented in a study that measureddecreases in height, head circumference, andchest circumference with increasing lead lev-els (Kafourou et a l , 1997).

Within the past 10 years, it has becomerecognized that polyvinyl chloride (PVC, or

20 Volume 67 • Ntjmber 5

Lead Content of Artificial Christmas Tree Needles

ID

CH 01CH 02

CH 03CH 04

CH 05

C H 0 6CH 07

CH 08

Blank

*ND: less

Type

NewNewUsedNewNewUsedUsed

Used

than 25 |ig/g.

Manufacturer

The Christmas House

Holiday Tree and Trim

PuleoChristmas Direct

Tree Classics

American Tree

Hudson Valley Tree

General Form Plastic

Length of Service (Years)

00

1300

1767

Pb (Mg/g)

*ND

m1.527

NDND

7.IMNDNDND

vinyl) plastic products often contain relativelylarge amounts of lead added as stabilizers. In1995, it was discovered that imported vinylmini-blinds contained so much lead that thesurface dust produced as a result of direct sun-light and heat was resulting in cases of acutelead poisoning of young children who han-dled and played with them {Norman, 1996;B.C. Lee of U.S. Consumer Products SafetyCommission, personal communication toM.F Toro, July 24, 1996). Studies conductedin 1997 found that several commonly usedchildren's products, such as PVC raincoats,hook hags, and beach bags accumulated highlevels of lead on surfaces after exposure tosunlight (DlGangi, 1997; Maas, Smith, Patch,& Thornton, 1997).

Artificial Christmas trees made of PVChave become very common in the UnitedStates; out of the 76 million family groups inthe country, an estimated 50 million house-holds own and use them (Fields & Casper,2001). Nearly 20 million of the trees in thesehouseholds are nine years or older (U.S. Bu-reau of the Census, 2000). Thus, there is apotential for lead exposure from the handlingof the trees during assembly disassembly, androutine usage, as well as from contact with ar-eas underneath the trees. The purpose of thisinvestigation was lo begin to determine thepotential lead exposure from typical house-hold usage of these products.

Experiment 1Eight 7-foot artificial (PVC) Christmas trees,each from a different major manufacturer,

were employed for part of this study Fourof these trees were newly purchased, and theother four had heen in residential use for peri-ods ranging from 7 to 17 years. The new treeswere sent directly from the manufacturer, andlength-of-service documentation for the usedtrees was provided by Foundation F.A.R.T.H.of St. Louis, Missouri. The manufacturer andtree specifications are summarized in Table 1.A sample of ihc needles (0.25 grams |gl-0.69g) was cut from each tree for subsequent leadanalysis. Tree needle samples were ashed forfive hours at 400°C before acid/hydrogenperoxide digestion.

F;ach tree was then assembled in the labora-tory by an investigator after a thorough hand-washing. Before and after assembly, the sub-jects hands were wiped with a laboratory wipeto remove all metal/dust material present onthe hands. Each wipe was hot-block-digestedaccording to National Institute for Occupa-tional Safety and Healtli (NIOSH) Method7082 (NIOSH, 1994) with concentrated nitricacid and 30 percent hydrogen penwide, andthe digestate was analyzed for lead.

Following assembly, a new clean laboratory'paper surface 120 centimeters (em) x 120 cmwas placed under each tree. Investigators tookwipe samples weekly for four weeks by wipingthe entire area with a laboratory wipe. Theytook control samples by wiping an immediatelyadjacent treeless laborator)' paper surface 120em X 120 em. All viipe samples were digestedas described above with nitric acid and hydro-gen peroxide. The laboratory where the treeswere erected had windows only along a longnorth-facing wall, so no direct sunlight stmckthe trees. At the conclusion of the four-week

experiments addressing surface dust deposi-tion, each tree was disassembled and placedback into its storage box by a subject, with thehands wiped before and after disassembly (asnoted above for the assembly procedure) todetermine how much lead was transferred tothe hands during disassembly

All digested uipe satnples were analyzedlor lead according to Standard Method 3113B(Clesceri, Greenberg, & Eaton, 1998) forelectrothermal atomic absorption spectrom-etry (EAAS). This method basically involvesdigesting the wipe in a hot concentrated mix-ture of nitric acid and 30 percent hydrogenperoxide followed by EAAS analysis. Calcula-tions were then made to express the amountof lead on the gloved hands in terms of thetotal mass (in pg). The lead content in theplastic needles themselves was calculated asmicrograms of lead per gram of needle (i.e.,|.ig/g, or ppm), and the lead in the settled dustbeneath the trees was expressed as pg/cm' ofsurface area.

Experiment 2In this experiment, research testing kits weremailed to 127 households that had orderedthe kits from Foundation E.A.R.T.H, Theavailability of the research kit was announcedto the public primarily through a Christmasseason evening news story carried by 73 NBCnews affiliate stations across the United States.Hach testing kit contained instructions, a re-search questionnaire, sample identification la-bels, a laboratory' wipe, one plastic headspacevial, and a pair of laboratory gloves. Individu-als were instructed, upon receipt of the kit, toopen the plastic vial to have it ready to accepttbeir wipe sample. Next, participants put onthe gloves and removed imd unfolded the lab-orator>- wipe. A Christmas tree branch sectionapproximately 30 cm in length was selected,and the wipe was carefully wrapped aroundthe branch section. The participants took thewipe sample by applying pressure and pullingthe wipe over the entire 30 cm section. Afterthe first wipe sample was completed, the wipewas folded in half so that any dust was on theinside of the iold. A second pass was madewith the same wipe; it used a second 30-cmbranch section following the same methods.The wipe was folded a second time and placedinto the plastic vial, which was then capped. Asample identilication label was affixed to thevial, and the kit was mailed back to the authors'laboratory, where the wipes were analyzed lorlead. Digestion and analysis of the wipes wereconducted with the same methodology as in

December 2004'lottrniil of Environmental Hoallh 21

BLE2Lead in Settled Dust Beneath Standing Christmas Trees

ID

CH 01

CH 02

CH03

CH 04

CH 05

CH06

CH07

CH08

Blank

Manufacturer

The Christmas House

Holiday Tree and Trim

Puleo

Christmas Direct

Tree Classics

American Tree

Hudson Valley Tree

General Form Plastic

Week 1(Mg/IOOcm^)

0.127

0.0538

0.424

0.114

0.298

2.43

0.0807

0.0129

0.0107

Week 2(Mg/IOOcm^)

0.0980

0.0258

1.71

0.207

0.0893

3.20

0.109

0.475

0.0151

Week 3(Mg/IOOcm^)

2.66

0.157

4.98

0.107

0.157

5.39

0.133

0.0635

0.02S8

Week 4(Mg/IOOcm^)

0.171

0.539

1.16

0.170

0.114

5.94

0.IS7

0.151

0.0732

Total(Mg/lOO cm^)

3.06

0.775

8.28

0.596

0.658

17.0

0.479

0.701

0.125

Experiment I. Calculations were made lo ex-press [he amount of lead in each wipe in termsof ihe total mass (in micrograms).

Participants also were asked to fill out a re-search questionnaire. The questionnaire wasused to determine the number and ages ofchildren in the household, child involvementin handling of the Christmas tree, length oftree ownership, manufacturer of the tree,counir)' of origin, approximate age of tree,and location of tree storage in ihe off-season.The questionnaire also asked what the partic-ipant would do with the tree if it was found tohave high lead levels. The choices included•"discard iree and buy a real tree," "dispose oftree and buy another artificial tree," or "takeextra care to avoid lead exposure when set-ting up and using the tree."

Results and Discuvsion

Experiment 1Table 1 summarizes the metal concentrationsfound in the \ inyl needles themselves. Two ofihe used trees exhibited relatively high levelsof lead, with the used American Tree samplehaving high levels of lead. The levels of leadwere nondetectable in the other six trees.These results suggest that lead was used morecommonly as a PVC stahilizer in die pasl.

The results of dust wipe samples taken be-neath the laboratory-erected trees are sum-matized in Table 2, Only used-tree specimensCH03 and CHOb exhibited relatively high leadlevels in the settled dust, which is consistentwith the metal-assay results shown in Table 1.A scenario oi actual lead exposure for the sam-ple with the highest lead level, American Tree,

can be made under the assumption that youngchildren might crawl and otherwise place theirhands on the affected under-tree surface (floor.wrapped presents, etc.) once per week duringa four-week Christmas tree season and pick upperhaps 25 percent of the total dust in the 1.49nr area, for a total of 630 pg. The U.S. Consum-er Products Safety Commission (CPSC) hasestimated, based on various bebavioral stud-ies, tbat approximately 50 percent of hand-ab-sorbed material will be ingested by a child threeyears of age or younger (U.S. Consumer Prod-uct Safety Commission, 1997), which wouldentail, in this case, in an approximate acute in-gestion of 315 ^g. This figure would equate loapproximately 0.86 pg/day ingestion spread outover an entire year. Califomias Proposition 65requires a warning label if a consumer productresults in an average daily lead exposure of 0.5jig'day or greater. CPSC does not classify a con-sumer product as hazardous unless it exposesthe average user to at least 15 H^day of lead;neither regulation specifies a limit for acuteshort-term lead exposures. The dust-wipe datalor the Puleo brand tree give an annual expo-sure estimate of about 0.42 ^g/day, just belowthe Proposition 65 limit, while the remainingproducts produce estimated daily exposuresbetween 0.02 and 0.16 pg'day, It is importantto note that even the six trees with nondetect-able lead content produced dust lead levels 4to 24 times background control levels, whichsuggests that all of the trees probably containedat least some lead stabilizer. These tests provideonly very rough exposure estimates becauseonly a single tree of each brand was tested, butthey do suggest at least some lead exposure po-tential even from new trees.

The mass of lead transferred to subjects'bands during assembly and disassembly ofPVC Christmas trees is summarized in Table3. Again, the results are consistent with theneedle lead concentrations shown in Table I,with trees CH06 and CH03 showing the high-est handling transfer levels. Sample CH06 re-sulted in a total lead transfer from assemblyand disassembly of 30.4 pg, which, spreadover a four-week Christmas season, translatesto a daily exposure of about 1 pg per day and,spread over an entire year, to about 0.1 (.ig/dayActual ingestion would most likely be only 10percent of these amounts for an adult and 50percent for a young child. Thus, lead exposurefrom assembly and disassembly would appearto be relatively minor compared witb exposureto a child playing around and under a tree.

Experiment 2A total of 127 in-service trees were tested intbis part of the experiment, and 42 trees, or33.1 percent, were observed to have detect-able levels of lead in their PVC needles. Thelower limit for the analytical method was1.5 ]xg of lead, Analysis of the questionnairedata showed that 66.7 percent of the house-holds with detectable levels of lead had chil-dren living in the household. Of this number,47.6 percent had children five years of age oryounger, while 23.8 percent had children twoyears of age or younger in the residence. Manyvolunteer participants were not able to deter-mine the tree manufacturer or manulacturerlocation, and thus no conclusions regardingthe relationship between ibe amount of lead inthe tree and the tree's manufacturer or countryof origin can be made from the data.

22 \'olume 67 • Number 5

BLE5Lead on Hands After Assembly and Disassembly of Artificial Christmas Trees

ChOIChO2

ChO3ChO4ChOE

ChO6ChO7Ch 08

Blank (\ig) Wipe Transfer {(jg)

<0.l 0.7<0.l 0.8

<0,l 6.9<0.! 0.2

<0.l 0.3<0.l 15.0<0.l 4.4<0.l 0.8

Blank {\ig)

<0.I<0.l<0.l<0,l<0.l<0.l<0.I<0.l

Wipe Transfer (pg)

0.5

0.32.30.80.9

15.41.20.5

BLE 4Mean Lead Mass andChristmas Trees

Number of treesin age category

Percentage of treesabove detection limit(1.5 lig Pb)

Mean lead mass onwipe fpg)

Estimated mean total directmouthing exposure overChristmas season (pg)

Estimated mean totalhand-to-mouth transferexposure over Christmasseason (pg)

Estimated

0-5

61

26.2

1.45

43.5

21.8

Lead Exposures from In-service Artificial

Age of Trees {Years)

5-10

21

23.8

0.91

27.3

13.7

10-15

16

37.5

4.48

134.4

67.2

15-20

9

33.3

2.92

87.6

43.8

>20

5

100

11.28

338.4

169.2

Of the 47 trees with detectable lead lev-els, 35.7 percent were stored in the base-ment, 28.6 percent were stored in the attic,and 14.3 percent were stored in the garage.Christmas tree storage location was consid-ered a relevant questionnaire inquiry; it hadbeen hypothesized that trees stored in loca-tions with higher temperatures might displaygreater lead levels since heat encourages thebreakdown of PVC materials. The data, how-ever, do not support this hypothesis. The at-tic was assumed to be the hottest storage lo-cation, but of the 40 trees that were stored inthe attic, only 30 percent had detectable leadlevels. Of the 15 trees that were stored in thegarage. 40 percent had detectable lead levels.

In the basement storage location, which wasassumed to be the coolest, 37 percent of 41trees bad detectable lead levels.

Table 4 sbows the number of trees in sev-eral tree age categories. The mean lead con-centration found in kit wipe samples, bytree age category; as well as the percentageof trees in each age categor)- with lead levelsthat exceeded the detection limit, are shown.Fifteen trees had ages that were listed on thequestionnaire as unknown, and results forl:hose trees were not included in the analy-sis. The data shown in Tahle 4 suggest that,while the percentage of artificial trees manu-factured with at least some lead stabilizer hasdecreased only modestly, the amount of lead

stabilizer used has apparently been reducedto a rnuch larger extent.

The last two columns in Table 4 deal withpossible lead exposure from the artificialChristtnas trees. Direct mouthing exposurewas calculated on the assumption of once-daily 100 percent transfer of lead from a30-cm tree branch to a child's tnouth over a30-day Christmas season. The scenario thatwas used for estimating exposure from hand-to-mouth transfer was a once-daily handlingof a 30-cm tree branch with a 50 percenttransfer rate over a 30-day Christmas season.A young child might likely handle more thanone tree branch per day A typical daily expo-sure might more commonly involve the han-dling of three branches per day on a 10-15year old tree; with this amount of physicalcontact, the child would be exposed to 6.72IJg/day of lead, or 201.6 pg over the Christ-mas season.

On average, the data collected from the wipesamples showed that exposure risks are gener-ally relatively low. Some percentage of youngchildren, however, will come into physicalcontact with their Christmas tree more thanonce a day, and some children will touch muchmore than just (me tree branch per day Thesefactors combined suggest that it is possible fora child to be exposed to a far greater amountof lead tban the data immediately suggest. Forinstance, if perhaps the worst-case scenario ofchild exposure involves a child who mouths10 tree branches per day on trees that are 20years old or greater, and in addition handles atotal of 300 cm of branch per day, the exposurefor this child could be as great as 225.6 ng perday, or 6,768 pg over the 30-day Christmasseason (or neady 20 ng/day averaged over theentire year). When one applies the Food andDrug Administration (FDA, 1993) 0.16 fac-tor for converting ng/day of lead exposure topg/dL increases in BLL, this value translatesto a BLL increase of over 3.0 jJg/dL. Extrapo-lation from the recent work of Canfield andco-authors (2003) produces an estimated lQdeficit lor this scenario of about 2.5 points.Although no studies have ever addressed therange of hand-to-mouth contact a young childmight have with an artificial Christmas tree,clearly many children will have much higherexposure than was estimated as typical in thisstudy With an estitiiatcd 50 million out of 76million families owning and using artificialChristmas trees in the L'nited States, and withalmost 11,5 million children two years of ageand younger living in the United States (U,S.Bureau of the Census, 2000), if even 50 percent

Deremlier 2004 • Jotirnol of Fin'ironm('nt<il I lt\ilth 25

of these children lived in a home with an arti-ficial Christmas tree, ihe most exposed I per-cent ol this populalion (a combination of themost dangerous child behavior and the treeswith ilie highest lead content) would have amuch higher exposure level than estimated forihc typical child; mathematically, ihis percent-age would translate to ahoul 57.500 children.

Conclusionsrhf experiments conducted in the first phaseof the research do not support the conten-tion ihiit the PVC Christmas trees currentlyhcing manufactured represent more than arelatively small lead exposure hazard acrossihe entire population of U.S. children. Thisconclusion is iempcrcd hy fbe fact that onlyone iree of each major brand was tested.

In contrast, two of the four older used treesihat were tested contained relatively high lev-els of lead (1,527 and 7,184 pg/g) in the PVC

needles. These levels are well in excess of theless than 400 ng/g that CPSC recommendschildren's products contain, and ingestioncalculations indicate that trees of these twotypes probably expose young children lo leadlevels at least in the range of California Prop-osition 65 limits.

While clearly not an acute loxicity threat bythemselves, a significant traction ol older arti-ficial trees are probably exposing children andadults 10 enough lead [o be at least a notewor-thy public health issue. The experiments de-scribed in this paper indicate that it is probablyappropriate to caution families—especiallyfamilies with older PVC Christmas trees, buteven families with new ones—to thoroughlywash hands immediately after tree assemblyand disassembly, and especially to limit the ac-cess of children to areas under erected trees.Direct mouthing contact, frequent branch han-dling, or both by young children would appear

to have the potential for causing lead exposuresof considerably greater health significance.

Data collected from the second phase of theauthors' research generally confirm that onaverage, lead exposure from artificial Christ-mas trees is relatively low. A worst-case sce-nario, however, would result in very harmfullead exposure. For the safety of all children,it is probabl)' appropriaic to request that PVCChristmas tree manufacturers formally com-mit to banning ihc use of lead in the PVCformations employed in these products. Un-til they do so, it would be wise to limit ihcamount ofphysical contact thai children havewith artihcial Christmas trees. ' ^

Corresponding Author: Richard P Maas,Co-director, UNC-Asheville EnvironmentalQuality Institute, CPO #2331. One Univer-sity Heights. Asheville, NC 28R04. E-mail:maas@unca.edu.

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Canfield, R.L.. Henderson, C.R., Cory-Slechta. DA.. Cox. C.Jusko,T.A., &• Eanphcar, B.P (2003), Inlellectual impairmeni in childrenwith blood lead conL-eniraiions below 10 pg per deciliter NewEnglandJouJTKil ojMedicmc. J48(16), 1517-1526.

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DiGangi, J. (1997) Lead and cadmium in vinyl children's products:A Greenpeace expose {Report No. 38). Washington. DC: Green-peace USA.

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Kaiourou. A., Touioumi. G., Makropoulos, V, Loutradi, A., Papanagiot-ou. A., & Hatzakis, A. (1997). Effects of iead on the somatic growthof children. Anhives oJ Environmental Health. .52(5), 377-383.

Kaufman, A.S- (.2001) Do low levels of lead produce IQ loss in chil-dren? A careful exatninaiion ol the literature. Archives of Clinical!^europsychology, 16 (4). 303- 341.

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Maas, R.P. Smith, R.M.. Paich, S.C., & Thornton, LR. (1997). As-sessment oJ potauial lead exposure jrom children's vinyl products(Tech. Rep. No. 97-043). .Ashville. NC: UNC Asheville Environ-mental Quality lnstiiulc. 18,

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Pocock, S.J.. Smith. M.. &r Baghurst, P (1994). Environmental leadand children's intelligence: A systematic review of the epidemio-logical evidence. British Medical journal, 309(6963). 1189-1197,

Sciarillo. W.G., Alexander, G., & Farrell, K.P (1992). Lead expo-sure and child behavior. American journal of Public Health, 82(10).1356-1360.

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24 Voltime 67 • Number 5