Evaluation of trace elements in human lung tissue I. Concentration and distribution

The Science o f the Total Environment, 54 (1986)217--230 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands

217

E V A L U A T I O N O F T R A C E E L E M E N T S IN H U M A N L U N G T I S S U E I. C O N C E N T R A T I O N A N D D I S T R I B U T I O N

C. VANOETEREN* and R. CORNELIS**

Laboratory of Analytical Chemistry, University of Ghent, Proeftuinstraat 86, B-9000 Ghent (Belgium) J. VERSIECK

Department of Internal Medicine, University of Ghent, De Pintelaan 185, B-9000 Ghent (Belgium) (Received December 10th, 1985; accepted January 6th, 1986)

ABSTRACT

The lungs of eight individuals were investigated for 27 elements by neutron activation analysis and atomic absorption spectrometry. Thirteen segments of each lung pair were analyzed, together with hilar lymph nodes. The trace element distribution in the lungs and the inter-individual concentration differences reveal the existence of two groups of elements. A similar situation is observed in the lymph nodes. The elements Br, Cs, Cu, K, Na, Rb, Se and Zn are relatively homogeneously distributed over a lung pair and show little inter-individual concentration differences. On the other hand, Cd, Co, Cr, Pb, Sb, Sc and V are very inhomogeneously distributed. The inhomogeneity and the concentrations increase with age. The existence of a concentration gradient within the lung and of relatively higher levels in the lymph nodes point to an enrichment in the lung tissue by inhaled atmospheric contaminants.

INTRODUCTION T h e lungs are the m a i n e n t r a n c e t o t h e b o d y f o r air-borne substances. M a n y o f these c o n t a m i n a n t s are capable o f p r o d u c i n g injury and disease w h e n d e p o s i t e d a n d a c c u m u l a t e d in sufficient a m o u n t s in the lungs. T h e c o n c e n t r a t i o n s o f trace e l e m e n t s in the lung tissue and their d i s t r i b u t i o n s in the o r g a n are c o n s i d e r e d to be a r e f l e c t i o n o f t h e e x t e n t and t h e n a t u r e o f e x p o s u r e t o a t m o s p h e r i c pollutants.

* Research Assistant of the Inter-University Institute for Nuclear Sciences. ** Senior Research Associate of the National Fund for Scientific Research (Belgium).

0048-9697/86/$03.50

© 1986 Elsevier Science Publishers B.V.

218 TABLE 1 DATA ON EIGHT INDIVIDUALS No.

Sex

Age (years)

Cause of death

Hospitalization time (days)

1 2 3 4 5 6 7 8

M F M M M M M F

74 17 33 19 19 18 73 84

Cerebral hemorrhage 2 Traffic accident 2 Work accident 5 Traffic accident 4 Brain tumor 3 Traffic accident 3 Brain tumor 117 Softening of the brain 6

3c/ F

Fig. 1. Division of the lungs into 13 segments.

SUBJECTS AND LUNG SAMPLE PREPARATION B o t h lungs and p a r t o f t h e t r a c h e a o f eight persons, b e t w e e n 17 and 84 years old, w e r e used f o r analysis, N o n e o f these p a t i e n t s died as a result o f a lung disease (see Table 1). Work and living e n v i r o n m e n t , as well as smoking habits, w e r e investigated. T h e lungs were t a k e n during a u t o p s y or at t h e o c c a s i o n o f a n e p h r e c t o m y f o r t r a n s p l a n t purposes. T h e y w e r e r e m o v e d as a w h o l e , p a c k e d into a specially cleaned T e f l o n bag, and s t o r e d at -- 35°C. T h e sub-sampling t o o k place in a clean r o o m . I m p l e m e n t s n e e d e d f o r t h e dissection w e r e rinsed with ultra-pure sulphuric and nitric acids and q u a r t z bi-distilled water. T h e lungs were p a r t l y t h a w e d and t h e n divided into 13 segments with a t i t a n i u m k n i f e (see Fig. 1). T h e samples were s t o r e d in cleaned p o l y e t h y l e n e vials, d e e p f r o z e n and l y o p h f l i z e d f o r 48 h. T h e d r y w e i g h t was a p p r o x i m a t e l y 20% o f t h e w e t weight.

219

A N A L Y T I C A L METHODS

The elements Br, Co, Cr, Cs, Fe, K, Na, Rb, Sb, Sc, Se and Zn were determined in all samples by means of instrumental neutron activation analysis (INAA). Detection limits were calculated for Ag, Ba, Eu, Lu, Mo and W and occasionally also for Au, Ce, Hg, La and Sm. About 300mg dry tissue, together with Bowen's kale powder and a laboratory-made multi-element standard, was irradiated for 31 h at 2 × 1012 n cm -2 s-1 in the Thetis reactor of the University of Ghent. After a cooling period of 5 and 20 days, respectively, the samples and standards were counted on a high-resolution Ge(Li) detector. The ~f-spectra were transferred to a VAX 11/780 computer and analyzed with a suitable programme [1]. A radiochemical extraction with cupferron was necessary for the determination of the short-lived isotopes 66Cu ( T i n = 5.1min) and S2V ( T i n = 3.76 min). This separation has been described in a previous publication [2]. The elements Cd and Pb were determined by flameless atomic absorption spectrometry (AAS). About 1 g dry tissue of every lung segment was ground and homogenized using the brittle fracture technique [2,3], ashed in a low temperature asher and dissolved in 1 N HNO3. As the residual matrix solution, made up to 0.1N HNO3, is still liable to cause interferences during the AAS measurements, the standard addition method was used. The samples were analyzed with either an atomic absorption spectrophotometer with Zeeman-correction (Hitachi 180-70) or with deuterium background correction {Perkin-Elmer 503).

RESULTS

R e p r o d u c i b i l i t y and accuracy

In order to check the reproducibility of the NAA method, a large quantity of homogeneous lung tissue was required. The different parts of the right lung of patient 1 were ground into a fine powder and carefully mixed to provide a single sample, of which eight sub-samples were analyzed. Analysis of variance yielded net standard deviations of 1--7%. The accuracy and precision of the AAS determinations were determined by analyzing SRM 1571 Orchard Leaves and SRM 1577 Bovine Liver. The Pb results for Orchard Leaves yielded a mean value of 45.3 + 1 . 1 # g P b g -1 (95% confidence limit) (certified value: 45 + 3 # g g -1 ). Lead and Cd data for the NBS Bovine Liver were, respectively, 0.36 + 0.04/~g Pbg -1 (certified value: 0.34 + 0.08/lgg -1 ) and 0.28 + 0.01/~gCdg -~ (certified value: 0.27 + 0.04/~g g-' ). Five different homogenized lung samples were analyzed for Cd by two different analytical methods: AAS and NAA with radiochemical extraction of Cd with Sb (DDC)3 [4]. The results agreed within 10%.

4.95 4.13--5.45 65.2 23.2--110 45.2 26.0--72.6 16.0 10.7--25.4 128 64.0--228 7.50 6.01--9.50 2.27 1.54--2.73 < 0.9

7.86 6.55--9.14 25.6 9.2--52.4 < 35

0.61

0.064

4.70 4.04--5.50 32.0 20.0--64.0 8.42 6.82--11.0 1.77 1.42--2.22 < 1.1

(ngg -1 )

Hg

< 124

< 68

(rag g- 1 ~0.43--1.17 0 . 0 4 5 - 0 . 0 9 2

Fe

(ng g-i

Eu

(~gg-1

Cu

(ngg -1

Cs

(ngg -1

Cr

(ngg -1

Ce (ngg -1 Co

(ng g-'

Cd

2.77--6.58 160 ) 60.9--229 < 49 ) 12.3 6.80--23.0 181 89.0--400 6.63 3.82--10.9 2.07 1.57--3.06 < 1.2

(ug g-' )

< 2.6

1.33 0.45--4.15 < 2.6

< 1.8

< 0.8

(ng g-' ) < 1.9 Ba (~g g-' ) 4.36 Br

Au

1.03 0.34--1.89 < 2.0

<49

5

3.30 3.52 2.65--4.09 2.73--4.38 239 85.0 99.8--472 27.6--181 98.1 54.6 62.0--137 1 4 . 9 - - 1 1 4 5.10 5.17 2.60--9.90 2.10--9.64 173 62.5 110--250 16.1--136 6.15 4.68 4.40--9.60 3.15--6.14 1.99 1.52 1.33--3.01 1.00--2.47 < 0.7 < 0.6

< 3.2

< 2.0

<20

4

0.098 0.093 0.084 0.063--0.143 0.073--0.134 0.041--0.135 < 102 < 73 < 86

< 27

<22

<15 Ag (ng g-' )

3

2

Element 1

Individual

12.7 2.57--25.6 151 58.2--354 7.06 4.39-12.3 1.71 0.89-2.90 < 5.4

8.70 6.10--9.64 126 56.4--226 < 44

< 3.0

< 0.9

<73

7

6.08 3.91--10.6 77.2 49.2--115 32.9 14.5--57.7 37.6 16.5-57.9 119 40.1--215 7.01 5.67--9.33 2.57 1.45--3.20 < 0.6

< 2.0

< 0.4

<9

8

1.94 +- 0.36

0.89--3.20

0.173 -+ 0.182

6.68 + 1.12

3.15--12.3

< 5.4

117 -+ 53

12.8 -+ 10.9

108 -+ 66

5.27 -+ 2.09

16.1--400

2.10--57.9

< 35--137

9.2--472

2.65--10.6

< 4.9

< 0.4--4.15

<73

0.081 0.186 0.167 0.040--1.17 0.040--0.182 0.107--0.358 0 . 1 0 4 - 0 . 2 2 3 < 85 < 130 < 58 < 130

3.37 2.67--4.01 87.3 23.5--156 65.2 33.7--97.1 8.69 4.11--12.0 87.5 41.1--119 5.98 4.80---7.70 1.61 0.93--2.29 < 1.1

~ 4.9

< 2.7

<54

6

Overall

M E A N C O N C E N T R A T I O N S A N D R A N G E S O F 27 E L E M E N T S I N BOTH L U N G S O F E I G H T I N D I V I D U A L S (Overall r a n g e a n d m e a n + s t a n d a r d deviation (wet tissue)

TABLE 2

t~ t~

Mo 270 ( n g g -~ ) 110--440 Na 1.76 ( m g g -1 )1.25---2.14 Pb 122 ( n g g -1 ) 81.0--174 Rb 1.74 (~ugg-l ) 1.21--2.55 Sb 35.5 ( n g g -l ) 19.5--48.1 Sc 1.97 ( n g g -1 ) 0.88--3.04 Se 130 ( n g g -1 ) 106--153 Sm ~ 2.3 (ngg -1 ) V 12.7 ( n g g -1 ) 4.70---21.3 W ~ 180 (ngg -I ) Zn 9.18 ( p g g - I ) 6.42--12.5

(rig g-I )

1.56 K ( m g g -l ) 1.08--1.90 48 La ( n g g -1 ) Lu < 1.2 ~ 730 2.17 1.67--2.85 119 100--173 1.91 1.47--2.32 22.7 15.2--30.6 2.86 1.33--4.70 247 125--515 ~ 6.6 26.8 14.0---47.8 ~ 290 11.5 7.88--14.9

1.86 1.59--2.15 67.0 28.7--112 1.73 1.36--2.10 6.98 4.27--9.68 0.49 0.36--0.79 66.0 41.7--91.0 ~ 2.1

7.43 5.75--9.86 ~ 131

11.5 9.40--14.2

~ 1.4

~ 0.9

~ 751

1.87 1.45--2.37 ~ 88

1.80 1.42--2.27 ~ 53

11.6 9.20---13.3

11.0 8.07--15.2 ~ 210

1.78 1.44--2.28 16.2 7.31--32.2 1.91 1.49--2.40 11.4 3.50---22.9 0.58 0.40--0.92 227 193--265 ~ 3.7

~ 780

2.37 1.92--2.95 33.9 15.4--61.9 "~ 1.7

10.1 6.89--13.8

17.2 6.29--34.5 ~ 290

1.99 1.61--2.59 13.8 6.79--21.0 1.87 1.27--2.55 9.65 5.20--14.8 0.79 0.24--1.59 170 68.8--231 ~ 6.4

~ 780

2.03 1.33--2.46 27.9 7.60--32.1 ~ 1.2

11.9 8.40--14.2

21.9 13.2--27.2 ~ 260

2.02 1.72--2.59 57.8 31.9--102 2.66 2.22--3.22 9.76 5.30--15.8 1.58 0.85--2.50 167 134--202 <: 3.4

~ 1100

1.92 1.63--2.28 20.2 12.7--35.6 ~ 3.6

8.91 3.91--14.6

13.5 7.96--23.0 ~ 120

1.87 1.24--2.24 60.9 36.0--105 2.29 1.64--3.04 12.3 6.60--19.0 1.78 0.37--3.08 239 138--381 ~ 7.7

~ 540

~ 1.5

1.64 1.17--4.27 ~ 36

10.8 6.80----12.5

14.4 0.91--27.9 "~ 110

1.59 1.02--2.09 63.3 21.6--129 2.21 1.55--2.84 15.9 4.64--48.2 1.96 0.71--4.56 130 110--142 ~ 2.0

~ 230

~ 9.3

1.74 1.21--2.18 ~ 32

2.04 +- 0.32 15.5 + 9.4 1.50 -+ 0.82 172 ± 63

1.21--3.22 3.50---48.2 0.24--4.70 41.7--515

3.91--14.9

290

0.91--47.8

10.7 ÷ 1.2

15.6 -+ 6.2

65.0 + 40.1

6.79--174

~7.7

1.88 -+ 0.18

1.87 + 0.25

1.02--2.85

110--<~ 1100

~9.3

7.60----<~ 88

1.08--4.27

t"O t'O

6.5 24.8 9.1 10.1 22.3 11.6 6.9 46.5 10.4 22.1 18.4 19.5 13.3 8.9

40.2 58.2 26.9 21.8 38.3 16.8

18.0 26.4 24.6 46.6 42.0 11.5 43.9 22.9

7.6 39.6 22.1 24.9 33.1 6.9 13.1 20.7 7.9 35.2 8.8 18.1 9.0 24.5 41.9 40.7 34.4 16.1

3 M(33) 18.1 46.7 19.8 30.1 23.4 14.5 22.6 16.3 11.3 21.6 12.2 40.9 12.6 34.9 25.1 5.5 22.6 10.0

4 M(19)

10.9 23.5 17.3 33.8 41.7 30.5 30.2 20.4

11.6 47.2 37.3 39.2 32.7 18.3 19.8 27.4 13.7

5 M(19) 11.3 71.2 25.5 21.7 20.5 11.8 24.9 37.9 9.1 34.1 10.9 29.1 10.8 33.3 27.1 9.8 17.6 14.3

6 M(18)

15.6 25.9 20.3 26.1 46.2 19.2 47.8 31.0

53.2 51.5 17.9 33.2 33.5 6.1

16.4 38.5

7 M(73) 28.2 35.6 39.2 32.1 60.8 14.5 16.9 20.6 18.5 58.0 12.3 45.9 15.2 75.7 62.9 6.7 59.4 15.9

8 F(84) 15.8 43.9 28.8 31.0 38.1 15.0 20.3 27.1 11.9 37.2 12.0 32.0 15.0 37.1 38.2 17.9 33.7 17.4

-~

7.9 11.9 8.9 14.0 16.3 6.2 7.2 8.5 4.3 15.2 3.5 10.9 5.4 17.4 14.1 12.4 15.9 7.2

S

N E T S T A N D A R D D E V I A T I O N F O R E A C H P A I R O F L U N G S (% $individual) ( m e a n a n d s o f t h e

a M : male, F --- female, age in p a r e n t h e s e s .

7.4 38.3

25.9 34.5

Br Cd Ce Co Cr Cs Cu Fe K La Na Pb Rb Sb Sc Se V Zn

2 F(17)

1 M(74)

Element

% 8h~dividuala

THE ELEMENTAL PERCENTAGE data )

TABLE 3

t~

223 (a)

(b)

°I ~Ts 8

815 //', [z 10

/ / ~\

,,"

/

"~ Zn . . . . . . . . . . . . . . ~ Rb 3O

g5

7 Lungsegrnent s

2o

O5

//.

/

V

.~,, "',Cr ~ \ ~ ' ~ . v Sc ~Sb

Fig. 2. Relative concentrations of eight elements in the seven segments o f the right lung of an 84-yeax-old woman (patient 8). (a) Caesium, Rb and Zn. (b) Cobalt, Cr, Sb, Sc and V.

Trace element concentrations

The results of the determination of 27 elements in the lungs of eight individuals are given in Table 2. The data represent the mean values of both lungs and the concentration ranges over the different sections. The elements Au, Cd, Ce, Co, Cr, Cs, Hg, La, Pb, Sb, Sc, Se, Sm and V occur at the nanogram per gram level (wet tissue). Concentrations of Br, Cu, Rb and Zn are at the microgram per gram and Fe, K and Na at the milligram per gram level. The most striking feature is the clear inhomogeneity of the elements throughout the lungs. An F-test showed that the distribution of almost all elements is less homogeneous than in the homogenized lung. The concentrations and the distribution of the elements depend on the size, the chemical composition and the solubility of the inhaled particles and on other factors that influence particle deposition and retention. An attempt was made to classify the elements according to the individual net standard deviation. For every element and lung pair, the total variance was calculated: 2 2 + Stotal ~-~ Scounting statistics -~ S a2n a l y s si S i2n d i v i d u a]

224

The percentages Sindividual are summarized in Table 3. These results infer the presence of two types of elements: (i) Br, Cs, Cu, K, Na, Rb, Se and Zn, which are relatively homogeneously distributed (Smdividu~,< 30%) and (ii) Cd, Ce, Co, Cr, Fe, La, Pb, Sb, Sc and V, which have a well-defined inhomogeneous distribution and also exhibit large inter-individual differences. The distinction between both groups is illustrated in Fig. 2, which shows the relative concentrations of the elements Cs, Rb, Zn, Co, Cr, Sc, Sb and V in the different segments of the right lung of an 84-year-old woman. The concentrations were normalized according to:

10

0

~9 (Z

.

I

• ..,~ . . Na

K

Rb Zn

Br

t •

... •

Cu Cs Fe Ce Se

Co Cd Pb

V

Sc

Cr Sb

Fig. 3. R a t i o o f t h e m a x i m u m t o m i n i m u m values o f 17 e l e m e n t s in e a c h individual lung

(n = 15).

225

x~

x

+ 1

where x is the mean concentration of element i in the right lung. The ratio of the m a x i m u m to minimum values of 17 elements in each individual lung is shown in Fig. 3. The lowest ratio was found for Br, and the highest for Cr and Sb, which shows not only the differences between the elements, but also those between the individual lung pairs. Trace element distribution

The trace element distribution over the different lung segments requires further investigation. Some authors have established that some elements (Co, Cr, Ni, Sb, Sr and Ti) show a positive concentration gradient from the base of the lung to the top (apexes), whereas Cd often appears to be higher in the middle lobe of the right lung [5--7]. Although only eight lung pairs were analyzed in this work, the examination of 13 segments allowed a more thorough study of the distribution patterns compared with other studies [5--7]. The assertion that the concentrations of some elements are higher at the top of the lung rather than at the base could only be partly confirmed. The older individuals (73, 74 and 84 years old) exhibited a similar distribution pattern. Figure 2 illustrates that Co, Ce, Sb, Sc and V are indeed more concentrated in the segments of the upper lobe. The highest concentrations of Cs, Cr, Rb, Zn and Cd were found in the middle lobe of the right lung. The younger patients, between 17 and 33 years old, showed a different trace element pattern. The previously mentioned trend was much weaker and sometimes even inversed, especially in the left lung. An explanation for the absence of such a concentration gradient in the lungs of younger persons has already been suggested by Joosting [8]. The deposition of particles is less important in the upper lung than in the lower parts due to breathing patterns and the influence of gravity forces. The particle retention, on the other hand, is greater in the upper lobe because the elimination mechanisms are less efficient in this zone. This last aspect becomes more important with aging.

13 o

12 11

9 8 7 6 5 3 2 !

000000 Zn K R b N a C s C u S e Br CeV SbScCr C o P b C d F e

Fig. 4. R a t i o o f m a x i m u m to m i n i m u m m e a n values o f 17 e l e m e n t s in eight l u n g pairs.

Ce

Co

Cr

1 2 3 5 6

Patient

1.02 1.83 2.70 2.61 1.60 2.16

K (mgg - I )

< 14 ~ 27 <~ 32 ~ 14 < 13 13

58.7 55.7 326 19.1 42.6 107

La (ngg -1)

7.07 7.08 4.07 5.67 3.28 8.48

0.91 3.8 3.2 4.7 2.8 2.6

~ ~ < ~ ~ ~

1.0 1.7 3.4 3.7 1.8 1.6

Lu (ngg -1)

<: ~ <: ~ ~

~ ~ ~ ~ <: <:

459 268 655 287 229 203

Mo (ngg -1) 1.03 1.70 1.03 1.81 1.98 2.37

Na (mgg-1)

150 100 722 90.6 191 319

1.33 1.47 3.01 1.98 2.04 3.08

Rb (ggg-1)

43.1 16.4 242 14.7 19.9 31.7

113 60.0 479 71.9 75.3 93.3

Sb (ngg-1)

746 511 2884 307 487 946

1.27 6.82 1.93 1.99 1.87 2.96

Br

1 2 3 5 6

Ba

(/~gg-1) (ngg-1) (ngg-1) (ngg-1)

Au

Patient (ngg-I) (ngg-1) (pgg-1)

Ag

TRACE ELEMENTS IN THE LYMPH NODES (concentrations per gram wet tissue)

TABLE 4

16.2 5.55 93.3 4.93 7.05 12.5

Sc

73.3 209 120 256 253 289

Se

< 2.0 < 1.5 10.1 ~ 1.3 ~ 1.2 ~ 1.5

Eu

9.61 3.67 58.2 2.08 3.86 6.62

Sm

0.355 0.088 0.568 0.057 0.063 0.131

Fe

< < < < < <

W

49.6 140 110 104 154 276

Hg

Zn

151 151 195 118 258 159

7.60 12.4 15.8 12.9 8.87 13.6

(ng g-1 ) (ng g-1 ) (ng g-1 ) (ng g-1 ) (/~gg-I)

9.69 12.5 51.2 7.22 8.25 14.3

Cs

(ngg-l) (ngg_i) (mgg_1) (ngg_1)

bO bO

K (mgg-1)

1 (trachea) 1.32 2 (trachea) 1.38 (bronchi) 1.58 3 (trachea) 1.26

Patient

6.9 6.7 6.1 7.5

~ < < <

12 14 26 19

La (ngg-1)

1.48 2.64 0.36 1.70

1.4 1.2 1.2 1.1

~ < < <

0.6 0.5 0.6 0.6

Lu (ngg-1)

"~ < ~ ~

~ 287 < 342 < 63 < 446

Mo (ngg-1)

2.21 7.17 6.33 3.37

20 15 25 16

2.19 2.51 2.27 3.08

Na (mgg-l)

< ~ ~ ~

1.81 1.18 1.42 1.16

Rb (pgg-1)

4.59 1.83 3.21 4.18

10.9 6.86 1.67 3.53

Sb (ngg-1)

10.7 14.1 14.9 7.08

0.20 0.41 0.15 0.14

Sc (ngg-1)

7.03 5.41 6.46 4.18

1.4 0.8 0.7 0.5

108 110 122 104

Se (ngg-1)

<: < < <

~ < < <

1.8 2.1 0.7 2.7

Sm (ngg-1)

0.074 0.031 0.031 0.029

49 56 43 48

~ <: < <

101 129 134 103

W (ngg-1)

< < < <

Ag Au Ba Br Ce Co Cr Cs Eu Fe Hg (ngg-1) (ngg-1) (/~gg-1) (~gg-l) (ngg-1) (ngg-I) (ngg-1) (ngg-1) (ngg-1) (mgg-1) (ngg-1)

1 (trachea) < 2 (trachea) < (bronchi) < 3 (trachea) <

Patient

TRACE ELEMENTS IN TRACHEA AND BRONCHI (concentrations per gram wet tissue)

TABLE 5

7.67 7.36 5.66 7.08

Zn (pgg-1)

t~

228

Relation between concentration, distribution pattern and age The data in Table 2 shows that the concentrations of Cd, Co, Cr, Sb, Sc and V differ distinctly from one individual to another, while the concentrations of the other elements are much more similar. There is no linear relationship between the concentrations and age, but, in most cases, the highest values for Cd, Co, Cr, Pb, Sb, Sc and V are found in the lungs of the older donors; they also exhibit higher net individual standard deviations, as shown in Table 3. The ratio of the maximum to the minimum mean values of 18 elements in eight lung pairs is illustrated in Fig. 4. The elements with the more inhomogeneous distribution within one lung also show the most important interindividual differences. The enhanced Fe ratio is due to the high Fe concentration in the lung of patient 1 as a consequence of the presence of a large amount of residual blood.

Analysis o f lymph nodes and trachea Apart from the lung tissue, lymph nodes from the hilus zone were collected and analyzed. L y m p h nodes play an important role in the elimination mechanisms of the respiratory system. They are considered to be deposits of inhaled material. The concentrations of 23 elements obtained by NAA are given in Table 4. The contents of Ce, Co, Cr, Eu, Hg, La, Sb, Sc and Sm are much higher than those found in lung tissue. The values for Br, Fe, K, Na, Rb, Se and Zn are lower than, or equal to, those in the lung tissue. Cadmium, Cu, Pb and V were not determined because of the small amount of material available. The enrichment of the previously mentioned elements has been confirmed by other investigators [5,6,9--11]. Table 5 lists the concentrations of 23 elements in the trachea or main bronchi o f three individuals. The concentrations of Au, Br, Co, Cs, K, Na, Rb, Se and Sm are comparable with those in the lung tissue. The contents of Cr, Eu, Fe, Sb, and Sc are lower than those in the lung tissue.

Relation between trace element concentrations and life style It was difficult to establish a link between the trace element pattern and individual life style since only eight persons were investigated and five of them were young. Lewis et al. demonstrated that smoking is the most important source of Cd contamination [ 12]. The mean Cd concentrations in the lungs of three young male smokers (patients 3, 5 and 6) were significantly lower than those in the lungs of the two older, male smokers (patients 1 and 7), b u t much higher than in those of a 17-year-old, non-smoking w o m a n (patient 2). The Cd concentrations were exceptionally high in the lungs o f an 18-year-old man who smoked (patient 4), and he also had higher Cr, La and Se concentrations. His medical history revealed a previous severe lung disease which might have influenced the trace element concentration.

229 CONCLUSIONS The analytical data reported here for the trace elemental composition of lung tissue can be summarized as follows. (1) The concentrations of Cd, Co, Cr, Pb, Sb, Sc and V are usually higher in the lungs of older people. (2) These elements are very inhomogeneously distributed within one lung or lung-pair of each subject. (3) The inhomogeneity is more important in the lungs of older individuals. (4) The inter-individual concentration differences are the highest for Cd, Co, Cr, Pb, Sb, Sc and V. (5) There is a positive concentration gradient towards the upper lung segments. This gradient is more obvious in the lungs of older individuals. (6) Cerium, Co, Cr, Eu, Hg, La, Sb, Se and Sm are enriched in the lymph nodes. As a general conclusion, it can therefore be assumed that Cd, Co, Cr, Pb, Sb, Sc and V are enriched in the lung tissue due to the presence of inhaled atmospheric contaminants. The elements are probably present as insoluble compounds. Indeed, n o t all elements in the atmosphere are liable to influence the lung concentration. Although the atmospheric Zn concentrations are high, the lung Zn levels are rather constant within one lung pair and hardly differ from one person to another. It is therefore likely that this element rapidly dissolves in lung fluids and blood. The results published in this article have been included and evaluated in a critical review on normal levels of major and trace elements in human lung tissue [ 13].

ACKNOWLEDGEMENT The authors gratefully acknowledge the support of the Inter-University Institute for Nuclear Sciences.

REFERENCES 1 J. Op de Beeck, Programme OLIVE, Internal Report, Institute for Nuclear Sciences, Ghent, 1973. 2 C. Vanoeteren, R. Cornelis, J. Versieck, J. Hoste and J. de Roose, Trace element patterns in human lung tissues, J. Radioanal. Chem., 70 (1982) 219---238. 3 G.V. Iyengar and K. Kasperek, Application of the brittle fracture technique (BFT) to homogenise biological samples and some observations regarding the distribution behaviour of the trace elements at different concentration levels in a biological

matrix, J. Radioanal. Chem., 19 (1977) 301--316.

4 J. Versieck, J. Hoste, L. Vanballenberghe and F. Barbier, Trace element measurements in serum by neutron activation analysis. Use and Development of Low and Medium Flux Research Reactors, Proc. Int. Syrup. Cambridge, Massachusetts, U.S.A.,

230

5

6 7

8 9

10 11

12

13.

Supplement to Vol. 44 ofAtomkernenergie Kerntechnik, pp. 717--723, Karl Thiemig, Miinchen, Germany, 1984. P. Bartsch, A. Collignon, G. Weber, G. Robaye, J.M. Delbrouck, I. Roelandts and J. Yujie, Distribution of metals in human lung: analysis by particle induced x-ray emission, Arch. Environ. Health, 37 (1982) 111--117. M.M. Molokhia and H. Smith, Trace elements in the lung, Arch. Environ. Health, 15 (1967) 745--749. G.W. Gibbs and E. Bogdanovic. 1975. Trace elements in lung and hair. Recent Advances in the Assessment of the Health Effects of Environmental Pollution, Proe. Int. Symp. Paris, France, 1974, Vol. IV, CEC, EPA, WHO, EUR 5360, CEC, Luxembourg, pp. 2271--2283. P.E. Joosting, Depositie van a~rosolen in de ademhalingswegen, De Veiligheid, 5 (1979) 419--425. E.J. Hamilton, M.J. Minski and J.J. Cleary, The concentration and distribution of some stable elements in healthy human tissues from the United Kingdom, Sci. Total Environ., 1 (1972--1973) 341--374. D.V. Sweet, W.E. Crouse and J.V. Crable, Chemical and statistical studies of contaminants in urban lungs, Am. Ind. Hyg. Assoc. J., 39 (1978) 515--526. N.A. Larsen, B. Nielsen, H. Pakkenberg, P. Christoffersen, E. Damsgaard and K. Heydorn, Concentrations of As, Mn and Se in organs of uraemic and normal persons determined by NAA, Nuclear Activation Techniques in the Life Sciences, Proc. Int. Symp. Bled, IAEA, Vienna, Austria, 1972, pp. 561--568. G.P. Lewis, W.J. Jusko and L.L. Coughling, Cadmium accumulation in man: influence of smoking, occupation, alcoholic habit and disease, J. Chronic. Dis., 25 (1972) 717--726. C. Vanoeteren, R. Cornelis and E. Sabbioni, Critical evaluation of normal levels of major and trace elements in human lung tissue, Report EUR 10440 EN, Commission of the European Communities, Luxembourg, 1986.