and

H. C. French

C.H. 1972/N:5Marine 1fummals Committee

Bundesforschung~n'\oft

fit' Fischerei Hamburg

Bibliothek

P. B. Heppleston

by

Nature ConservancyMonks Wood Experimental StationAbbots Ripton, Hunt ingdon , England

Seals Research DivisionInstitute for ~Jarine Environmental Researchc/o Fisheries LaboratoryLowestoft, Suffolk, England

MERCURY AND OTHER MmALS IN :BRITISH SEALS

International Council forthe Exploration of the Sea

This paper not to be cited without prior reference to the author1L

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. Introduction: ond ,Hethods.

Increasing concern about environmental 'pollution ~as led to many

investigations,of heavymetals and their distributio.n in the sea, air

and biological materials. However thore have.: beel'l. few investigations

01' seals in this regnrd; the prescnt pnper gives some·proliminary,

results 01' nnalyses 01' British senls •

. ,. Srunples' \lere tnkan from ninety-six senls (Toble 1), both Common. . . . .. '" .... . ;

seals (Phoca vitulina) ,and Grey. seals (Halichoerus .B.~~), fro~ six

sites around Britain betweenFcbruary 1968 and January1912•. Thcy were

collected.during the course 01' 10ng-term.populatioI,l.stu~ies at major

British senl locnlities und the opportunity uas taken 01' procuring

tissue samples for chemical analysis from those areas vinited on a

~o~tine basis in 1911-12. It uas not possible ~o select seals b~.nge

because th~y do not~hange apprcciably in extornnl. fcnt~es after renCh­

ing.physieal,mnturity. Henee in the srunplcs.from some arens.there are

gaps ..;in the middle age-groups. Data from East. Anglia for bothsP7ci~s

. ~ere~ pooled bocause 01' small somple sizes.. Sarnples 01' brain and liver

~~re,obtained frocr ~ost seals and kidney and tocth from ab~~~,~_!~ird.

,.,~issues were placed individually in uncontar:J.inated polythcne bags. and ._ • c. • ....

stored a.t - 200C. ThG uot samples'\lcrc digcstcd in nitrie neid und

total: mercury: uas cstimated by a flameless tcchnique using a Pcrkin­

E~~r·303 atomie absorption spcctrophotomctcr (AAS).Cadmi~ in soft

tissues 'I1OS cstimnted by AAS using a,1'10l110 .tochnique '~;' Tocth,;co~~.~,cted

from'1968 onvtards, vtore dissolved in nitrie ncid and,subsequcntly,

examined ona Porkin-Elmo~~305AAS for le~d, cadmium, copper, chromium

and zine•. The ago ofsoalsylD.s detormincd by oxamination 01' canine

teeth (Laus 1953, Heuer 1964) •

.Hesults. (TabIo 2) .

. . , Ther~!'IICrO regionnI ..variations in mcrcury conccntrations in ;\;ho

brain,. docrensing in thc order Hehrideo, !~rne I,slands, East A~li.a,

\k~t Scotland,Shetland; the resulto from the Hebrides and Farne

It3,1ands ,lore significantly greater than thone.framell other ,regions.,., . '. "','. , c""" , •

These variations may be duc in part ~o, the differcntial.PQ~sage01'."

mercury compounds from thc 1?loodto 'l?rclin tissue.•..Methyl-mcrcury,

uhiCh i8 cx~:;,cm?,ly toxic: (Lofroth 9 ,1968) i8 ,kno~m. to ,pas,s this bnrrier

uÜh ease (Lofroth, ~968, Kurland ot al'.:,1960) compared to inorgBnic

und mont ,organic mcrcuriols.

1

.Vith the e.,'<:ception of Common seals from 'ilest Scot land 9 the concen--. . '.

trat ions of mercury in the brain did not increase ~ith age of the seals

(se~ Fig. 1); this suggests that a ceiling level is reached early in

life. The 'brain-barrier' effect has previously been recognized in

toxicologic l'studies (Friedmann, 1942).

Concentrations of mercury in the liver uere positively correlated

uith the age of the seal (Fig. 2) in five out of the six areas. The

exception uas found in livers from Shetland seals ~hich also had lo~er

levels than those from all other areas. An analysis of combined data

from all areas gave a correlation coefficient of .78 (p < 00001).

Analysis cf variance on the transformed data for all areas shoued that

there ~as an overall significant difference betueen some of the slopes

CF = 2.9799 P ~ 0.05). It is apparent that the difference is due to

the East Anglia and ~est Scotland regressions having greater slopes

(ioe. higher build-up of mercury in liver) than the other three areas.

88 per cent of the seals from the East Anglia / West Scotland group \7ere

P. vitulina; seals from all other areas uere ~. grypus. Houever, any

conclusions about differences beh/Gen the species must remain tentative

at present, since the age spectra of aach group differed, "ith more

older seals in the samples of Ho grypuso Further extensive sampling

is needed to establish if the straight line model for Log of mercuryeaccumulation ~ith age is adequate.

Cadmium v/as found in comparatively lC'.rge quo.ntities (up to 22 p.p.m.)

uet"uei ht in all kidncys (Table 2) but brains and" livers conto.i~ed

less than 1 p.p.m. Concentrations in kidneys tended to increase uith

age (p 0 •001) •

Mercury end cadmium in pup tissues vo.ried in relation to levels in

their mothers (Table 3) and in general reflected the tendency for some

metals to shou an age-accumul tion in certain tissues. Other studies

have shoun that the placenta constitutes 8 barrier to the passage of

most mercury compounds "except methyl-mercury (Eerlin"& Ullberg, 1963)

which passes into the foetus easily ~nd m~ rench a concentration

comparnble with that in the mother (Ackefors, 1911).Lco.d 9 zinc and chromium were found in molar tceth, vith cadmium

and copper in smaller quantities (Table 4). Analysis of the data in

relo.tion to age of the seals shoued a progressive decrease in concen-

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trations of leed, cadmium end chromium, the major change uith lead occur­

ring at 8bout 5 - 7 yenrs ,of age (Fig. 3); young seals contained higher

lead levels than older individuals (p < 0.001). This may reflect the

fact that, initially, enamel, cement and d~ntine are laid ßOPll_tpgether,

in molar tceth; after about 5 years only smnll amounts of biologieally

inert, cement are dcposited (Heqer, 1964). From this time onuards, there­

fore, relatively little extra material is incorporeted into tho tooth nnd

it is to be expec~ed that metal concentrations uill,tend to remain stnble

or decrease slight1y uith the slou accretion of cemant. Metal concentra­

tions in tecth from seals nged 5 or more should therefore reflect, to

some extent j the cone ntrations of metamencountered during the fir~t

4 or 5 years of life. The levels of zine, houover, sho~ed areverse

trend, inereasing ~ith age. Regional eomparisons of metnls in teeth

rev~aled, no elcar pattern, but cadmium nnd lead deercased thus: Orkney

and Shetland, Ea~t Anglia, Hebrides, Farna Islands. Thore uas no-signif­

ieant difference between lend residues from Scotland and East Anglia.

Conclusions.

Thi's preliminary study suggests that:

1. r~crcury ranches a ceilillg level in brninsat about age 12 - 18

months; residues in man reach si~ilar levels and also shou no

eorrelation uith age (Kurlcnd et al, 1960, Gl~nski et al, 1971) •

. 2." MercJW tends to accumulate in the liver with age, reaehing..... ---. . -. --- - - .- ~.

fairly high levels •

3. Cadmium eecumulates in the kidney, es it does in man (Schroeder

and Belasse, 1961), qhere it is known to oceur in higher con­

eentrations thon in other organs (Tipton et al, 1960). ,

4.- Thcr~dö not appear to be regional differenccs in the concen­

trations of metals in ~eeth, but some mctels were found'in greater

~uantitie~ in younger seals than in old ones; this is probably

relnte.d to the pattern of tooth c;rowth.

5. Thera are regional differences in the a~ounts of mercury in seal

tissues, but there qoes not soem to be an obvious relationship

'with known c.grieultural or industrinl pollution:

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These results demonstrate the importance of taking oge into occount

when studying the amounts of metals in,biologicol tissues.

cknolfledgements.

The \7örk \72.S supported by the Natural Environment Research Co.uncil..,

.. es part of the programmes of the Institute for Marine Environmontnl

'Research and the Nature Conservancy. Dr J E Portmann (Ministry of '

Agriculture, Fisheries and Food, Burnh~u-on-Crouch) nrranged for the tooth

... nnalyses. Members of the Seals Research Division assisted \7ith the col­

lection of sampies ond tooth exnmination.

REFEnENCES

Ackefors, H, (1971), ,~ rcury pollution ~n Sweden \7ith special reference

to' oonditions in thc ',7ater habitat. Proc" Roy, Soc. Lond. B.

ill: 365-387.Berlin, M. & Ullberg, S. (1963). Accumulction end retention of m0rcury

in the mouse .llrchs. Environ. Hlth . .§.: 589-601, 602-609, 610-616.Eastoe, J.E. (1961). Teeth. Biochemists ' Handbook (ed. by C Long): 721­

723. Spon, London.

Friedemann, U. (1942). 'Blood-bro.in rorrier'. Physiol. Rev'~ 22rl.25--153.Glomski, C.l ., Brodoy, H~ & Pilloy, 3.K.K. (1971). Distribution ond

concentration of mercury in eutopsy specimens of human brain.

Nature 232: 200-201.Hewer, H.R. (1964). The determination of age, sexual mc.turity, longevity

and 0 life-toble in the Grey saal (Hnlichoerus grypus). Proc.

zool. Soc. Lond. ~: 593-624.Kur land , L.T., Faro, S.N. & Siedler, H. (1960). IÜnooata Disense. Wld.

Neurol. 1: 370-395.Lons, R.M. (1953). ü ne\7 mcthod of sge deterrninntion in mnr-unals, uith

special reference to ,the Elephont seal (Nirouns2. leonina L.).

Falkland,.Islands Dependencies Survey Sci. Rep. No. 2. pp 11.

Lofroth, G. (1968), Methylmercury. A reviev of th health haznrds and

sidc effects associated with the emission of mercury compounds

into natural s;ystcms. SV/cd. Ecol. Res. Comm. Bull. No.4.

Schrocdor,H.A. & Belassa, J.J. (1961). Abnormal trace metals in man:

cadmium. J; ehron. Dis. 11: 236-258.

Tipton, I. H. (1960): The di~tribution of trace motels in thc human

body. Metal-binding in 1fudicine (cd. by M. J. Seven) : 27-42.

Lippincott, Philadelphia.

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Tab1e 1 Geographica1 distribution and age-groups of seals sampled

Area Spccies 0-0.9 1.0-5.9 6~10.9 11-15.9' 16-20.9 21-25.9 yrs

, ,

1. Wash P.vitulina' ,9 I ,2 1

" ,1 ~ ,~

2. Scroby, S d H.grypus, an s'

:',

1 (1) :'

" , P.vitulina '" 2>,".

3

4~' WestScot-, H.grypusland

;'.,"~

5. Outer: H.gry"pus_, Hebri~es.....:

P.vitulina' '4

2 2, 1 (2)

,:

,(I), ,

2

"2" 3

"4

" (2) ,

3

.5H.grypus

"'\

,\-,

3. FarneIs1es•

•I

6. Orkneyand : H.grypusShctland

~.

,!

4 (9): 3 (5) ,1

, .....

"'( )',' " ~

. ,,,'

.' .• t ••

Figures in parentheses indicatu additional: seals fro~:whidh toothsampIes on1y werc taken~

Seals >1ere aged to,the nearest I1ho1e ycar,; but have been grouped to, I

simplify tho tablc .

. . ~ .

.,!

Tab1e 2: Mercury end cadmium concentrations in British seals. Mean velucs ~ s.d. in p.p.m. wet TIoight

_._-- ._---l:.xGas 1 & 2 Aren 3 Aron 4 .Aroh 5 l-..ren 6

East Anglia Farne Islands West' Scotland Outor Hebrides Sh3tland

Hg Hg Hg Hg Hg Cd Hg Hg Hg Hg ; Cd Hg Hg Cdbrain liver kidncy brain livor kidney brain liver brain liver kidnGY train livor kidney

0·4 29.9 13.1 0.1 84.2 5.3 0.4 30.1 0.1 113.0 11.6 0.3 4.9 2.2

,~ Oi2 ~ 38.1 ± 0.2 ~ 0.2 ± 68.9 ±. 4.0 ±. 0.1 ~18.2 ~ 0.2 ~ 68.0 ~ 7.5 ~ 0.1 ~ 3.6 ±. 2.0

(13) , (15) (2) (7) (7) (5) (8) (9) (6) (6) (4) (8) (8) (8)

Figures in brackcts arG the numbor of snmp1es.

Cpdmiun va1ues for all brain and 1ivor snmples were 1ess than 1 p.p.m.

php [lnd foctus velues (involving ereas 3,4 and 5 only) havc bOGn omitted froI:l thoch1culations, since thoy represent pollutonts dorived from their mother; amotherand her pup/foetus can be considered as one end the seme marino-feedin~ unit.

---- ---- -----~

/.1. ~ ... ~ .'

; :~: " ~.

,, '

. / '.'" ~

"'.'

'1 "

0.06(5)

Mercury in liver, Cadmium in kidney

". '"

" ..J'

Mercury'inbrain

.'0.51(5)

' .'M

.

5. OuterHebrides

'" .. ~,' '~xpressed as raean 'values p.p.n.viet \7eight

': . ~',}';' ~.- ",

Table 3: Grey' 'seal ..,; pup/t:1other ratios', of 'mercuryand c'admiuo residues

( .. '/- )

nuober of observations (pup-mother pairs) are shown in

_._" -,_ ,,,. "." .• ,,'0, ",._- " •• :P.l3.l?E3~~~~S.~s." ••, " .-.. "_,' , " '" .,." ''''', "'" " _.

3. Farne<, ( .._I~~~nd~ . ,

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. Table 4: >Lead, 'zine, ehromium,eopper and.. eadaliurn. .. ... . ,. ,.' . .

concontrations.in Grey seals. Mean ~ s.d.

p.p.n. dry TIeight (see Eastoc, 1961)

J.\rea ,," .. Lead Zinc' 'Chrooiün" , Copper .Cadmiumn

1. East 20 }6.7 ~ 7.5 103.9 ± 56.4 19.9 ±. 7.9 4.9 ~ 6.2 3.9±.0.82. Anglia'

," '}.

! ."

3. Farne 15 }0.6 ± 7.7 142.4 ± 63.6 14.7 ±' 6.5 6.9 ± 5.3 3.5 ± 0.5Islands

4. Outer/. 13 32.7 ±.10.5 145.8 ± 66.9 14.3 ~3.9 4.1 ± 1.8 3.8 ± 0.75. Inner "

Hebrides, . '. : . .

(West Scot.)

6_.0rkney.15. 37.0 + 10.4 85.2 + 45.3 18.1 + 8.4 4.7 + 4.7 5.2 + 2.5and - .. .. . . . . - -. --- ~ _. -' - .- --.. - . ::-:. .Shetland

•

p < 0.001 P > 0.1 P < 0.05

Correlationvlith ageof seal 63 p < 0.001

(-ve)

p < 0.001

(+ve) (-ve) (-ve)

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Fig. 1: Mercury in seal brain (p.p.m. wet weight total mercury)

ppm Hg

o

0.8 • •

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24200.0 '~r---T---r-~--r--r-~.,......,~--r--.-....,-..,.--r--r-'1~--r--.-....,-..,.--r--'T

o 4 8 12 16

AGE (yeti,s)

• Correlation of concentration with age

• East Anglia r - 0'.459 p > 0.10 Farne Is. r = -0.068 p > 0.1

• o. Hebrides r = 0.545 p > 0.05A West Scotland r = 0.778 p 4: 0.01A Shetland r = -0.537 p ) 0.1

Fig. 2: Mercury in seal liver (p.p.m. wet weight total mercury)

•24

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2016

'lA

12

AGI (}fe.ra)

8

• •

4

5

4

3

. _.

._ -:'::'-0- - -:::.":.-0-- -"..... - -::'._0

_- -_7---'0'-,. ,.'_.. .-' 0--. .-a A • __ - _,_.-

• _ _ 6. ._'

6 ~_/-~:::.:~~~...~:~.'.~••••••

. • -' /'-'-... 6'"2 .; -:;i~7 ... ~...~............ ·

;v·~., ••• •h ~,?."".,•\

1

-1

LOtI. ppm ....

6

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Fig. 3: Lead and cadmium in seal teeth

• Grey seal

o Common seal

Results expressed as p.p.m. fresh tooth; this approximates to

a dry weight figure, since teeth containonly 5 - 1~0 water

CEastoe 1961).

The lower limits of detection were: Lead ca. 2.~ p.p.m.

Cadmium ca. 0.5 p.p.m.