21
Chapter 4
Priority Contaminants, `New' Toxic Substances,
and Analytical Issues
Ivan C. Burkow and Jean-Philippe Weber
(PCNs), polybrominated diphenylethers (PBDEs), poly-
Summary
chlorinated paraffins, and perfluoroorganic compounds
Ongoing monitoring of persistent toxic substances
(e.g., perfluorooctane sulfonate PFOS) are identified as
(PTSs) in the Arctic has focused on three well-known
`new' toxic substances. Of these, PBDEs, polychlori-
groups of contaminants: industrial compounds and by-
nated paraffins, and PFOS have recently received particu-
products, chlorinated pesticides, and heavy metals. How-
lar attention. Due to their distribution and accumulation
ever, increasing levels of several `new' contaminants and
pattern, the synthetic musks, phthalates and new gener-
metabolites are a cause for concern. Brominated flame
ation pesticides are generally not considered a particular
retardants, polychlorinated paraffins, and perfluoroor-
problem in the Arctic. None of these `new' compounds
ganic compounds have recently received international at-
are on the current UNEP list of most unwanted POPs.
tention, but more data on their presence and possible ef-
Increasing interest in the metabolites or halogenated
fects are needed to evaluate their environmental impact.
phenolic compounds is partly caused by their structural
Interpretation of monitoring results requires reliable
similarity to natural hormones (see Figure 4·1) and pos-
and comparable data, a condition not always met.
sible action as hormonal mimics (Connor et al., 1997;
Therefore all laboratories producing human PTS data
Hovander et al., 2002). In addition, many of the well-
for AMAP are required to participate in relevant inter-
known toxins are chiral (exist in mirror image forms)
calibration programmes and to achieve acceptable results.
and hence exist in enantiomeric pairs (Kallenborn and
Where relevant, measurements should be congener-spe-
Hühnerfuss, 2001), which have the potential to cause
cific and the data lipid-normalized for the organic pollu-
different biological effects. An enantio-selective accumu-
tants, and speciated for the heavy metals to distinguish
lation has been reported for several organochlorine com-
toxic and non-toxic forms.
pounds (Karlsson et al., 2000; Wiberg et al., 2000). That
the enantiomers may have different biological effects has
in most cases been overlooked when assessing the pos-
4.1. Persistent toxic substances
sible environmental impact of these compounds.
Most research and ongoing monitoring work on PTSs in
Long-range transport allows many PTSs to reach re-
the Arctic have focused on three groups of contami-
mote areas such as the Arctic, where few, if any, local
nants: industrial compounds and by-products (e.g.,
sources of these contaminants exist. Depending on the
polychlorinated biphenyls PCBs, and dioxins), pesti-
geographic location of sources, weather conditions, and
cides (e.g., lindane, the DDT-group, and cyclodiene ana-
the physico-chemical properties of the contaminants,
logues), and heavy metals (e.g., mercury Hg, lead Pb,
and cadmium Cd) (AMAP, 1998; Hansen et al., 1996;
Jensen et al., 1997; Lønne et al., 1997). The Stockholm
Convention on Persistent Organic Pollutants (POPs) fa-
cilitated by the United Nations Environment Programme
(UNEP), and the U.N. Economic Commission for Eu-
rope (UN ECE) Protocols for Heavy Metals and POPs
also reflect the global concern associated with these con-
taminants. The UNEP POPs list includes aldrin, chlor-
Hydroxy
pentachlorobenzene
dane, DDT, dieldrin, dioxins and furans, endrin, hep-
tachlor, hexachlorobenzene (HCB), mirex, PCBs, and
Estradiol
Halogenated phenolic
compounds hydroxy-PCB
toxaphene. The UN ECE POPs Protocol includes the
(4-OH-2,3,5,3'4'-CB)
UNEP 12 plus chlordecone, hexachlorocyclohexane
(HCH), hexabromobiphenyl and polycyclic aromatic
hydrocarbons (PAHs). The UN ECE Heavy Metals Pro-
tocol initially focuses on Cd, Pb, and Hg. During the last
few years, however, there has been an increasing interest
in `new' toxic substances and metabolites.
The `new' environmental toxins cover a range of or-
Hydroxy-PBDE
Thyroxine T4
ganic compounds and compound classes. These include
(6-OH-2,4,2',4'-BDE)
some of the more persistent polar pesticides currently in
use. Other examples are nitro- and aromatic musk and
their metabolites from personal care products. Among
Figure 4·1. Structural similarities between the natural hormones
the industrial chemicals and by-products, phthalates, oc-
estradiol and thyroxine T4, and the halogenated phenolic compounds
tachlorostyrene (OCS), polychlorinated naphthalenes
hydroxy-PCB, hydroxy pentachlorobenzene and hydroxy-PBDE.
22
AMAP Assessment 2002: Human Health in the Arctic
transport to and within the Arctic can occur via the at-
fects on the immune system, cancer, reproductive distur-
mosphere, ocean currents, sea ice drift, and river systems
bances, and acute toxic reactions (Fiedler, 1996; Whys-
(AMAP, 1998; Burkow and Kallenborn, 2000). Due to
ner and Williams, 1996).
their persistence and high lipophilicity, several of these
compounds bioaccumulate, presenting a possible risk to
4.2.2. Polychlorinated biphenyls
humans, particularly those who depend on the lipid-rich
marine mammals (whale, seal and walrus) for food.
Polychlorinated biphenyls (PCBs) are a group of 209
Among the many thousands of synthetic bulk chemicals
congeners, several of which are atropisomers (i.e., exist
in use today, only a limited number have been tested or
as enantiomeric pairs due to restricted rotation of the
evaluated for their hazard potential. To understand the
bond between the two phenyl rings). PCBs were com-
possible consequences for human health and the Arctic
mercially produced and sold mainly as Aroclor and
environment extensive evaluations are needed. It should
Clophen mixtures (Safe, 1994). Worldwide PCB produc-
be kept in mind that the consequences may only become
tion is estimated at 1.3 million tonnes (Breivik et al.,
apparent decades after emissions to the environment
2002). PCBs have been used extensively since the 1930s
have occurred, and thus after wildlife and people have
for a variety of industrial and commercial purposes, but
already been exposed. Evaluation criteria must therefore
their manufacture and new uses have now been phased
include propensity for long-range transport, persistence,
out in many western countries. PCBs have widespread
bioaccumulation potential, and hazards for human
applications, including as dielectric fluids in transform-
health and the environment (toxicity). Section 4.2 pres-
ers and large capacitors, as heat exchange fluids, in lu-
ents some key information for the most common and
bricating oils, as paint additives, in plastics, and in
most debated PTSs from non-occupational exposure in
sealants. At present, the major source of PCB exposure
the Arctic. More information about sources and envi-
seems to be environmental recycling of PCBs from for-
ronmental levels of contaminants in the Arctic can be
mer usage. PCBs are still present in older electrical
found in two related assessment reports: the AMAP
transformers and at a number of contaminated indus-
2002 assessments of heavy metals (AMAP, 2003b) and
trial and waste sites throughout the Arctic. Like most
POPs (AMAP, 2003c).
POPs, PCBs have primarily contaminated the Arctic
ecosystem through long-range transport from more
southern regions.
4.2. Industrial chemicals and by-products
The physico-chemical properties of PCBs, including
4.2.1. Dibenzo-p-dioxins and dibenzofurans
low water solubility, high stability (particularly those
Commonly known as dioxins and furans, polychlori-
lacking unsubstituted positions on the biphenyl rings),
nated dibenzo-p-dioxins (PCDDs) and polychlorinated
and semi-volatility, favor long-range atmospheric trans-
dibenzofurans (PCDFs) are two structurally similar fam-
port and accumulation in lipid-rich media. Thus, the
ilies of, respectively, 75 and 135 congeners. Dioxins and
main source of human exposure is through diet; how-
furans are mainly released through relatively low temper-
ever, inhalation and dermal routes are likely under occu-
ature (below 800 °C) domestic and industrial incinera-
pational exposure scenarios. Typical PCB values in
tion processes, with chlorine present, as well as during
plasma are in the range 1 to 60 g/L (AMAP, 1998).
the manufacture of industrial chemicals including PCBs
Historical levels are not always easy to compare with
and pesticides (Alcock and Jones, 1996; Fiedler, 1996).
contemporary measurements due to changing trace ana-
A significant reduction in the emissions of dioxins and
lytical techniques and quantitative methods. PCB val-
furans to the environment has been achieved through
ues are often reported based on different quantitative
the implementation of pollution control measures.
methods (e.g., as Aroclor 1260 or a selected number of
Dioxins and furans are insoluble in water, lipophilic,
congeners), making comparisons difficult. Co-elution
persistent in the environment, and toxic. In particular,
with other chlorinated compounds like chlorobornanes
the 2,3,7,8-tetrachlorinated dioxins are known to bioac-
and cyclodiene pesticides has previously made reliable
cumulate, while the more predominant congeners from
analytical interpretation difficult.
combustion processes are known to biodegrade. Because
The most persistent congeners in lipid media are
they bind to particulate matter, dioxins are normally re-
CB99, CB118, CB138, CB153, CB170, and CB180.
garded as a major problem close to the source. In addi-
Although regarded as persistent, some PCBs, depending
tion to a few local sources, these compounds enter the
on chlorine substitution, are transformed in the environ-
Arctic ecosystem via long-range atmospheric transport,
ment by biotic and abiotic processes. Naturally occur-
but not to the same extent as for the other chlorinated
ring microorganisms are capable of degrading the low
PTSs. Diet is the main route of human exposure in the
chlorinated PCBs with vicinal hydrogen atoms. The
Arctic. Typical PCDD/F values reported in human milk
presence of PCB metabolites in animals and humans
from the Arctic are in the range 10 to 40 pg/g lw (lipid
formed by the action of CYP (cytochrome P450) and
weight) (AMAP, 1998); data on levels in human plasma
phase-II enzymes is recognized (Boon et al., 1989), but
from the Arctic are, however, sparse.
to date these have not been included in environmental
New methods for sample extraction and clean-up
monitoring programmes. Reports have shown that the
have improved the analytical capability for dioxin/furan
most abundant hydroxy-PCBs in human blood samples
trace analysis and pooled blood samples are no longer
equal the presence of some abundant PCB congeners
needed when using the most modern clean-up and quan-
with sum values in the range 0.1 to 10 g/L (Bergman
titative techniques.
et al., 1994; Hovander et al., 2002; Sandau et al.,
Chloracne is a well documented effect following
2000a). Metabolism also includes the formation of di-
dioxin/furan exposure. Other possible effects include ef-
ols, phenolic conjugates and glutathione conjugates.
Chapter 4 · Priority Contaminants, `New' Toxic Substances, and Analytical Issues
23
Methyl sulfone metabolites are also reported to bioaccu-
4.2.4. Polychlorinated paraffins
mulate (Letcher et al., 1998), but are present in substan-
tially lower amounts compared to the hydroxy com-
Short-chain chlorinated paraffins (SCCPs) are part of
pounds.
the group of polychlorinated-n-alkanes (PCAs) with up
Several possible adverse human health effects to PCB
to 30 carbon atoms and a chlorine content of 30 to 70%
exposure have been suggested, including effects on the
by mass (Tomy et al., 1998). PCAs are used as additives
immune system, cancer, effects on the reproductive sys-
to improve water repellent and flame retardant proper-
tem, and cognitive development (Safe, 1994). Some of
ties in metal working fluids and lubricants, plastics,
their toxicity may be linked to the biotransformation
adhesives, paints, and sealants. The SCCPs have carbon
products. Due to structural similarities (with hydroxy
lengths of 10 to 13 and are of particular interest because
group in para- or meta-position), the hydroxy metabo-
they have the greatest potential for environmental re-
lites are assumed to be able to mimic hormonal activities
lease and the highest toxicity of the PCAs. Information
(Connor et al., 1997; Kester et al., 2000). The non-ortho
on historical production volumes of PCAs is difficult to
and mono-ortho substituted PCBs are planar with toxic
find but annual global production during the 1990s was
properties similar to the dioxins.
estimated at 300 000 tonnes, of which 50 000 tonnes
were SCCPs (Muir et al., 2001). Due to concerns about
their possible environmental impact the use of SCCPs
4.2.3. Chlorinated naphthalenes
is declining.
Polychlorinated naphthalenes (PCNs) exist as 75 con-
SCCPs are relatively mobile, subject to long-range
geners that are structurally similar to the PCBs with
transport, and are found in the Arctic. Studies indicate
comparable chemical and thermal stability (Falandysz,
that SCCPs are less persistent and bioaccumulative than
1998). PCNs were first used commercially in the early
PCBs hence levels in the environment are low compared
1900s for wood, paper, and textile impregnation, but
to PCBs (Fisk et al., 2000). Medium- and long-chain
were shortly thereafter replaced by PCBs. The numerous
chlorinated paraffins are not yet reported in the Arctic.
industrial applications also include usage in electrical
In contrast to most other environmental toxins, the
equipment (e.g., capacitors and cables), lubricants, sol-
number of SCCP congeners is extremely high, and this
vents, dyes, and sealants. Technical PCN formulations
has resulted in a substantial analytical challenge. No
have been found under the names Halowaxes, Seekay
congener-specific analysis exists, as this inability to re-
waxes and Nibren waxes depending on manufacture.
solve the individual components causes major problems
Other sources of PCNs in the environment are technical
for quantitation. A high degree of variability has also
PCB formulations (up to 0.09% PCN) and thermal
been reported in the quantitation depending on the ana-
processes (e.g., combustion, roasting, metal reclaiming,
lytical technique used.
and the chlor-alkali industry). PCNs are also believed
SCCPs appear to elicit fewer acute and chronic toxic
to be formed during combustion of PAHs. In the
effects when compared to PCBs, but information is very
1920s, worldwide annual production was approxi-
limited. Risk assessments of SCCPs are inconsistent with
mately 9000 tonnes. One of the largest PCN producers
respect to their conclusions regarding ecological risk, in-
voluntarily ceased production in the late 1970s. How-
cluding carcinogenicity, clearly indicating the need for
ever, general information about world production vol-
more data (Muir et al., 2001).
umes and history is limited. Although the use of PCNs
has declined in the past few decades, they are not pro-
4.2.5. Brominated flame retardants
hibited in most countries and still occur in many PCB-
like applications.
Polybrominated diphenylethers (PBDEs), polybromi-
PCNs are transported to the Arctic mainly via long-
nated biphenyls (PBBs), and tetrabromobisphenol A
range atmospheric transport. Partitioning to aerosols is
(TBBPA) are the three main classes of brominated com-
especially important, governing both transport path-
pounds used as flame retardants (Renner, 2000). Bromi-
ways to remote areas and depositional patterns. PCNs
nated flame retardants (BFRs) are used extensively in a
are lipophilic and, as for PCBs, the chlorine substitution
variety of consumer products such as in thermoplastics
pattern governs their persistence (Falandysz, 1998).
for televisions and personal computers, building materi-
Knowledge of the actual levels and distribution of spe-
als, foams for furniture and insulation materials, as well
cific congeners in humans is very limited. Data on
as in textiles. BFRs are either chemically incorporated
human liver and adipose tissue indicate PCN levels 200
(covalently bound) in materials or applied as an additive
to 500 times lower than the total PCB burden (Wei-
to the material; BFRs from the latter group can more
strand and Norén, 1998). Hydroxylated metabolites of
easily migrate into the environment. The major commer-
PCN have also been reported.
cial products include the covalently bound TBBPA and
The analytical challenges associated with PCN ana-
its derivatives (representing a third of production), the
lysis are the same as those for non-ortho substituted
additive PBDEs (representing a third of production), and
PCBs and dioxins; highly sensitive and specific trace-
a number of other compounds. PBBs for use as an addi-
analytical techniques are required. Although all 75 con-
tive flame retardant are no longer produced. The annual
geners have been synthesized, full congener separation is
usage and variety of compounds manufactured have
not yet possible due to co-elution.
drastically increased during the last few years, with an
Some of the PCN congeners appear to exhibit
annual world production of over 150 000 tonnes in
dioxin-like toxicity of a similar magnitude to some of
1998 (Larsen et al., 1999).
the co-planar PCBs (Falandysz, 1998; Villeneuve et al.,
The physical properties of BFRs encourage long-
2000).
range transport and accumulation. That BFRs are found
24
AMAP Assessment 2002: Human Health in the Arctic
in air and biological samples from remote areas of the
cult and there is a need for sophisticated LCMS meth-
Arctic supports the indications that these substances are
ods for proper quantitation.
globally distributed in the environment. Although de-
PFOS has been shown to affect cellcell communica-
cabromodiphenyl ether (BDE 209) accounts for most
tion, membrane transport, energy generation, and prox-
PBDE use, the most commonly found congeners are the
isome proliferation (Sohlenius et al., 1993; Upham et al.,
tetra and penta derivatives. Typical values of PBDEs
1998), but concentrations in wildlife are believed to be
(mainly BDE 47 and BDE 99) in plasma are in the range
lower than those required to cause adverse effects.
5 to 40 ng/L (about 0.5% of levels of PCBs) (Darnerud
et al., 2001). Recent findings of increasing PBDE levels
4.2.7. Octachlorostyrene
in temporal trend studies, and the general lack of data
on these substances, underline the importance of further
Octachlorostyrene (OCS) is an industrial by-product
investigations on these compounds (Norén and Mei-
formed during electrolysis of salt solutions to produce
ronyté, 2000).
chlorine and magnesium, and when purifying aluminum
With increasing availability of reference compounds,
(Deutscher and Cathro, 2001; Selden et al., 1997). Max-
quantitation of the major congeners can be achieved.
imum releases probably occurred in the 1960s, but little
However, a complete identification and quantitation of
is known about global emissions.
all BFRs is not yet possible, and BDE 209 is often omit-
Although found in high levels close to industrial
ted when the PBDEs are reported. Studies indicate effec-
sites, OCS has not been regarded as a major contami-
tive uptake from the gastrointestinal tract and substan-
nant in the Arctic. However, the metabolite 4-hydroxy
tial breast milk transfer to offspring. The formation of
heptachlorostyrene has recently been identified as one of
metabolites is also reported.
the major metabolites in human plasma in the Arctic
Although little information is available, data on pos-
(Hovander et al., 2002).
sible effects suggest that PBDEs are likely to be carcino-
No particular problems are associated with OCS
gens, endocrine disrupters, and neurodevelopmental
analysis.
toxicants (Hooper and McDonald, 2000).
The potential human health concern with OCS is be-
cause it has a binding affinity for both the androgen and
estrogen receptor (Satoh et al., 2001). The metabolite is
4.2.6. Perfluorooctane sulfonate
believed to have an influence on thyroid hormone and
With the possible exception of chlorofluorocarbons
retinol homeostasis (Sandau et al., 2000b).
(CFCs), fluorinated organics have traditionally received
less attention than chlorinated and brominated organics,
4.2.8. Polycyclic aromatic hydrocarbons
partly because they are believed to be relatively inert and
therefore less likely to have an impact on human health
Polycyclic aromatic hydrocarbons (PAHs) constitute a
and the environment. A number of different chemical
large class of compounds, which comprise hundreds of
classes belong to this group (e.g., CFCs, aromatics, sul-
individual substances. They are produced as a result of
fonamides, acids and sulfonates). Perfluorooctane sulfo-
incomplete combustion (pyrolysis) of organic matter.
nate (PFOS), which belongs to the important class of
Sources are ubiquitous and include notably the burning
fluorinated surfactants, has, however, received more
and coking of coal, wood burning (including forest
attention recently (Giesy and Kannan, 2001; Kannan
fires), production of aluminum, emissions from internal
et al., 2001; Moody and Field, 2000). PFOS is used as
combustion engines (particularly diesel), cooking over
a refrigerant, a surfactant, and as a component of phar-
fire or hot coals, and cigarette smoking. The main sources
maceuticals, flame retardants, lubricants, paints, adhe-
of non-occupational exposure are cigarette smoke, smoke
sives, cosmetics, paper coatings, and insecticides. PFOS
from wood combustion, and smoked or broiled (over
has been manufactured for over 50 years and its many
charcoal or fire) food (IARC, 1983).
useful properties have steadily increased its use, making
PAHs released into the atmosphere by these combus-
PFOS a high volume product with an estimated U.S.
tion processes are rapidly adsorbed onto particulate
production of 3000 tonnes in 2000. As a result of the
matter and distributed into the different environmental
3M Company's phase out, U.S. production is anticipated
compartments. PAHs are hydrophobic and insoluble in
to decline.
water and are readily taken up in lipid deposits of
The strong CF bond makes fluorinated organics
aquatic organisms. PAHs are photooxidized by sunlight
more inert, both chemically and biologically, than the
in air and water. Since PAHs are biodegraded by mi-
corresponding chlorine or bromine analogues, and
croorganisms and metabolized by higher organisms,
hence they are expected to have an environmental per-
they show little tendency to bioaccumulate. Levels in hu-
sistence greater than the more well-known organic con-
mans are affected by smoking status, occupational expo-
taminants (Key et al., 1997). In general, however, little is
sure and consumption of PAH-containing foods. In non-
known about their biodegradation and accumulation
smokers, the levels of the metabolite 2-naphthol are
characteristics. PFOS has been detected in marine mam-
below 2 mol/mol creatinine, whereas smokers exhibit
mals from the Arctic, but no data exist on levels in hu-
average levels of 4 mol/mol creatinine. Higher levels
mans from this area. The physical properties of fluori-
are encountered in occupationally exposed individuals
nated organics encourage long-range transport, as they
(ATSDR, 1995).
are more volatile than chlorine or bromine analogues.
PAHs may be detected and measured by a number of
Part of the reason why PFOS received less attention
methods, based on their UV absorption, fluorescence, or
in the past was because its measurement is complicated.
molecular mass. Analysis is performed using a separa-
Due to its surface-active properties, extraction is diffi-
tion technique such as high performance liquid chro-
Chapter 4 · Priority Contaminants, `New' Toxic Substances, and Analytical Issues
25
matography (HPLC) or gas chromatography (GC) to en-
sure, with highest concentrations found in oils and fats,
able identification of individual members. Evaluation of
meat, poultry, and fish. Exposure via inhalation or
human exposure is performed through the measurement
through drinking water is considered to be low. Typical
of hydroxylated metabolites in the urine (including 1-hy-
plasma levels in Arctic populations are in the range 0.3
droxypyrene and 2-naphthol) using GCMS.
to 2 g/L (AMAP, 1998). HCB is transformed into both
Usually PAHs with two to six fused aromatic rings
pentachlorophenol (PeCP) and conjugates; however,
are those of toxicological interest. PAHs are not acutely
elimination appears to be small compared to adipose de-
toxic to humans. However, many PAHs have been
posits (To-Figueras et al., 2000).
shown to be potentially carcinogenic as well as geno-
In addition to inducing porphyria, HCB has a broad
toxic. Metabolites (e.g., hydroxides, epoxides, and
range of toxic effects in experimental animals including
nitro-PAH) appear to be responsible for these effects
immunotoxicity, endocrine effects, and cancer (Fisher,
(Angerer et al., 1997).
1999).
4.3. Chlorinated pesticides
4.3.3. DDT group
4.3.1. Hexachlorocyclohexanes
The use of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane
Hexachlorocyclohexanes (HCHs) are a group of
(p,p'-DDT) as a pesticide has been declining in the tem-
organochlorine compounds existing in eight isomeric
perate regions of the Northern Hemisphere since the
forms including the often-reported , - and -HCH,
1960s and especially since the mid-1970s when its pro-
the last more commonly known as the pesticide lindane.
duction and use were banned by many western nations
-HCH is chiral and hence exists as an enantiomeric
(Mellanby, 1992). DDT was commonly used as a pesti-
pair. The gamma isomer lindane is used as an insecticide
cide on a variety of agricultural crops and is still in use
on fruit, vegetables, and forest crops. Many countries
for the control of mosquitoes that spread malaria (vec-
still use large amounts of lindane and there are some reg-
tor control). Total global usage was estimated at 2.6 mil-
istered uses of lindane in some circumpolar countries.
lion tonnes up until 1992 (Voldner and Li, 1995). p,p'-
Technical grade HCH, mainly containing the alpha iso-
DDT is easily metabolized to 1,1-dichloro-2,2-bis
mer and only 15% -HCH, was once used as an insecti-
(p-chlorophenyl)ethene (p,p'-DDE) and 1,1-dichloro-2,2-
cide. Total world production is estimated at 0.7 million
bis(p-chlorophenyl)ethane (p,p'-DDD). The DDE/DDT
tonnes of lindane and 10 million tonnes of technical
ratio indicates age since release, or closeness to the
HCH (Li, 1999).
source of a release. Two minor isomers of the DDT
Owing to their physico-chemical properties, HCHs
group, o,p'-DDT and o,p'-DDD, are chiral.
are readily transported to the Arctic, via both atmos-
The persistence of the DDT group in the environ-
pheric and aquatic pathways. HCHs partition into all
ment and its continued entry into the Arctic region via
environmental media in the Arctic. Biodegradation
long-range atmospheric transport has meant that DDT
seems to be the dominant decomposition pathway in soil
is detectable in almost all compartments of the ecosys-
and water. Like other POPs, most human exposure to
tem and in human tissues. Levels of total DDT in human
HCHs comes from food consumption. HCHs are not a
tissue in the Arctic are considerably higher than those in
major contaminant in drinking water. HCHs, especially
most southern populations, reflecting biomagnification
-HCH, accumulate readily in fatty tissues and are ex-
in Arctic food chains and the higher consumption of
creted slowly via feces, breast milk, and urine. Because
high trophic level species for food in the Arctic. Typical
of its persistence, -HCH exhibits the highest concentra-
plasma levels are in the range 1 to 9 g/L (AMAP, 1998).
tion of the isomers normally reported in human samples.
DDT and its metabolites are stored in fatty tissue and
Typical plasma levels are in the range 0.1 to 2 g/L
excreted very slowly. Due to its lipophilicity, DDT and
(AMAP, 1998).
its metabolites are found in breast milk and can readily
Except for the general difficulties in separating enan-
cross the placental barrier.
tiomers, no problems are associated with HCH analysis.
Except for the possibility of decomposition during
High HCH exposure can affect the liver, the nervous
analysis, there are no general limitations connected to
system, the kidney, the reproductive system, and the im-
DDT analysis.
mune system. HCH is regarded as a possible carcinogen
Some evidence suggests that the DDT group may
(ATSDR, 1994; Coosen and van Velsen, 1989).
suppress the immune system, mimic hormones and be a
possible human carcinogen (Fisher, 1999).
4.3.2. Hexachlorobenzene
4.3.4. Cyclodiene pesticides
Hexachlorobenzene (HCB) was introduced in 1945 as a
fungicide for seed treatment. HCB is also an industrial
The cyclodiene pesticides are a diverse group of com-
by-product associated with the manufacture of chlori-
pounds including the chlordanes, heptachlor, aldrin,
nated solvents, and several metallurgical industrial
dieldrin, and endrin.
processes. It is a known impurity in several pesticide for-
Technical chlordane is a mixture of cis- and trans-
mulations that are currently in use. HCB is banned in
chlordane, cis- and trans-nonachlor, heptachlor and
many countries or its use has been severely restricted.
other chlordane isomers (Dearth and Hites, 1991). The
The estimated current global annual emission is 23
total number of compounds is at least 147, of which 10
tonnes (Bailey, 2001).
are major ones. Most chlordanes are chiral and hence
HCB is very persistent and bioaccumulates in ani-
found as racemates (mixture of mirror images) in the
mals. Dietary intake is the major route of human expo-
technical product. Chlordane was manufactured from
26
AMAP Assessment 2002: Human Health in the Arctic
the late 1940s as a broad-spectrum insecticide used on
It bioaccumulates, and is now found at low levels in
agricultural crops and for termite control. Total global
human tissue. The primary source of exposure is food,
usage has been estimated at 78 000 tonnes (Barrie et al.,
especially meat, fish, and game. Transformation to pho-
1992), and action to ban chlordane has been taken in
tomirex is slow and elimination is mainly via feces and
many countries. It is not registered for use in circumpo-
breast milk. Plasma levels in the range 0.1 to 0.6 g/L
lar jurisdictions and enters the Arctic ecosystem prima-
are reported (AMAP, 1998).
rily via long-range transport. The chlordanes are highly
Mirex has toxic and possible carcinogenic effects
volatile, lipid soluble and hence readily accumulate in
(AMAP, 1998).
fatty tissues in the marine food web. In general, only
small amounts of chlordane are found in human tissues.
4.3.6. Chlorobornanes
However, relatively larger amounts of trans-nonachlor
and the metabolites oxychlordane and heptachlor epox-
Toxaphene is an insecticide mixture introduced by Her-
ide are found. The chlordanes are one of the most abun-
cules (USA) consisting of several hundred chorinated
dant environmental pollutants. Typical values (sum of
bornanes (CHBs, the major product), polychlorinated
chlordanes) in human plasma are in the range 0.2 to 2
camphenes (PCCs), bornenes, and bornadiens, contain-
g/L (AMAP, 1998). No analytical limitations, except
ing six to ten chlorine atoms (de Geus et al., 1999; Muir
for the separation of the chlordane enantiomers, are re-
and de Boer, 1995). Comparable mixtures were used
ported. The compound class is a possible carcinogen and
under the brand names Strobane and Melipax. Most of
is believed to affect the immune system (Fisher, 1999).
the CHBs are chiral. Toxaphene is one of the most heav-
Heptachlor, also used as an insecticide against ter-
ily used pesticides, with a total world production of 1.3
mites, grasshoppers, and malaria mosquitoes, is now
million tonnes up until 1993 (Voldner and Li, 1993).
banned in several countries and severely restricted in
It was primarily used on cotton, cereal grains, fruits,
others. Heptachlor is metabolized in animals to hep-
nuts, and vegetables, as well as to control ticks and mites
tachlorepoxide. Typical plasma levels are in the range
in livestock. Toxaphene and comparable mixtures are
0.05 to 0.15 g/L (AMAP, 1998). As for chlordane, hep-
now banned in most countries.
tachlor is highly volatile, lipid soluble, and bioaccumu-
CHBs, the major constituent of toxaphene, are semi-
lates. The compound and its metabolite are classified as
volatile and enter the Arctic region via long-range at-
carcinogens (Fisher, 1999).
mospheric transport. The compounds are persistent
Aldrin is a pesticide used to protect crops such as
(half-life in soil up to 12 years), lipid soluble, readily ab-
corn and potatoes from grasshoppers and worms, and to
sorbed, and are commonly found in human tissue. Ab-
protect wooden structures from termites. Total global
sorbed CHBs may be transformed and excreted; how-
production has been estimated at 500 000 tonnes (Barrie
ever, some congeners remain for prolonged periods. The
et al., 1992). Aldrin is readily metabolized in plants and
two most common congeners are an octachlorobornane
animals to dieldrin. Dieldrin was traditionally used in
(Parlar no. 26) and a nonachlorobornane (Parlar no. 50).
agriculture to control soil insects, with a worldwide
Values reported in human plasma are in the range 0.1 to
total production of 34 000 tonnes. Today, primary uses
1 g/L for both congeners (Deutch and Hansen, 2000).
include controlling termites, woodborers, and textile
Quantification has been compromised by difficulties
pests. Endrin has been used as an insecticide on cotton
in analysis (separation from PCB and organochlorine
and grain, and as a rodenticide to control mice and
pesticides) and in the estimation of the amounts of the
voles. Aldrin and endrin have been banned or severely
various chemicals that make up the CHB mixture. The
restricted in most countries. Action has also been taken
increased number of reference compounds has improved
to ban or restrict the use of dieldrin, one of the most
the capability for acceptable quantitation of the most
common pesticides. Due to the persistence and lipo-
abundant congeners. However, the lack of standards, as
philicity of aldrin and dieldrin, these compounds readily
well as differences in how data on total CHB amounts
bioaccumulate. Endrin is rapidly metabolized by ani-
(or the sum of toxaphene-like compounds) are pre-
mals and does not accumulate in fatty tissues to the
sented, has made comparisons of published data on
same extent as the other compounds. The main source
CHBs difficult.
of human exposure is through food. Adverse effects in-
Several adverse effects of toxaphene, including being
clude toxicity, immune system depression, and carcino-
a possible human carcinogen, are reported (de Geus et
genic action (Fisher, 1999).
al., 1999). However, structureactivity models have shown
that the most toxic CHB congeners are not accumulated
(Parlar et al., 2001).
4.3.5. Mirex
Mirex is an insecticide primarily used to control fire ants
4.3.7. Pentachlorophenol
and other insects. Mirex has also been used as a flame
retardant in plastics, rubber, and paint. The compound
Pentachlorophenol (PeCP) is made by exhaustive chlori-
has never been used in any of the circumpolar jurisdic-
nation of phenol or by the hydrolysis (or degradation) of
tions and is now banned in many countries. It has been
HCB. PeCP is insoluble in water but is readily converted
manufactured and applied extensively in the United
to the soluble sodium salt. Depending on the manufac-
States and has reached the Arctic via long-range atmos-
turing process, PeCP may be contaminated with various
pheric transport.
dioxins and furans. Worldwide production is estimated
Mirex is one of the most stable and persistent pesti-
at less than 30 000 tonnes per year. As a broad-spectrum
cides with an environmental half-life of up to 10 years.
low-cost pesticide, PeCP and its salts have been used as
Mirex is readily absorbed and stored in fatty tissues.
algicides, fungicides, insecticides, molluscicides, and her-
Chapter 4 · Priority Contaminants, `New' Toxic Substances, and Analytical Issues
27
bicides. Current use is limited to the treatment of lum-
Arsenic forms a variety of inorganic and organic
ber, in particular utility poles. Because of its volatility
compounds. Among the first class, two oxidation states
and water solubility, PeCP evaporates or is leached from
predominate, trivalent (+3) and pentavalent (+5), readily
wood structures to a large extent (ATSDR, 1999a).
forming oxides, sulfides and acids. Organic forms in-
Environmental contamination is widespread, PeCP
clude methylarsonic acid (MAA), dimethylarsinic acid
being found in ambient air, surface and ground waters,
(DMA), arsenobetaine and arsenocholine, the last two
sediments, soil, and aquatic and terrestrial organisms.
found in seafood. In mammals, inorganic As is rapidly
PeCP is degraded by light and microorganisms to form
transformed (metabolized) into MMA and DMA and
numerous transformation products, of which penta-
subsequently rapidly excreted in the urine, thus making
chloroanisole and tetrachlorocatechol are the most
urine the medium of choice for evaluating recent As ex-
abundant in the environment. PeCP bioaccumulates in
posure. Care must be taken to speciate in order to dis-
fish but in mammalian systems it is rapidly excreted in
tinguish between toxic and non-toxic forms.
the urine, either free or conjugated with glucuronide.
To interpret the environmental or health impact of
A recent study of PeCP in blood shows PeCP concentra-
As its determination in environmental and biological
tions in Arctic samples of 0.6 to 8 g/L plasma (Sandau
samples must take into account the various species pres-
et al., 2000a).
ent. Total As content can be measured by atomic ab-
No particular difficulties are associated with PeCP
sorption spectrophotometry (AAS) using either hydride
analysis.
generation or graphite furnace (GF). Chemical pretreat-
PeCP is a suspected carcinogen, however contami-
ment allows a limited speciation to be made, sufficient
nants in technical grade PeCP may be the actual culprits.
to distinguish exposure to toxic forms from ingestion of
seafood. Inductively-coupled plasmamass spectrometry
(ICPMS) coupled with HPLC affords complete specia-
4.3.8. Endosulfan
tion of common inorganic and organic compounds
Endosulfan is a synthetic, sulfur-containing, organochlo-
(ATSDR, 2000b).
rinated hydrocarbon used as an insecticide and acari-
The toxicity of As compounds varies from highly
cide. Technical grade endosulfan is a mixture of two
toxic to non-toxic in the range As(III) > As(V) > MAA >
geometric isomers (conformers), alpha and beta, which
DMA > arsenobetaine/choline. Chronic As exposure af-
have slightly different physical and chemical properties,
fects several organs with resulting damage to the periph-
in a proportion of 2:1.
eral nervous system, skin, liver, and heart. Arsenic is rec-
Endosulfan is moderately persistent in the environ-
ognized as a human carcinogen (Smith et al., 1992).
ment. In soil, the half-life ranges from 30 to 200 days,
and is affected by pH, the presence of microorganisms,
4.4.2. Cadmium
and humidity. In water it is hydrolyzed slowly to form
sulfur dioxide and endosulfandiol. In mammals, endo-
Cadmium occurs in nature as oxides, sulfides and salts.
sulfan is absorbed rapidly though incompletely by the
Cadmium is released into the environment from both
digestive system. Endosulfan is lipophilic but is rapidly
natural and anthropogenic sources, with the former in-
converted to a number of hydrophilic metabolites, in-
cluding volcanic activity, and weathering and erosion of
cluding endosulfan sulfate, endosulfandiol, endosulfan
rocks. Mining, smelting and refining activities account
ether, and hydroxy endosulfan carboxylic acid, which
for the majority of anthropogenic emissions. Incinera-
are more easily excreted. Thus it does not accumulate in
tion of municipal wastes containing nickelcadmium
the fat, and hence shows little potential for bioaccumu-
batteries also contributes significantly. Soil levels are ele-
lation or biomagnification (ATSDR, 2000a).
vated close to sources, and usually decrease rapidly with
As a member of the organochlorine class, endosulfan
distance away, although emissions from tall stacks may
can be determined by GC with electron capture detec-
be transported over long distances (IPCS, 1992). Cad-
tion (ECD). For environmental and biological speci-
mium entering freshwater from industrial sources is rap-
mens, sample clean up and purification is crucial to the
idly adsorbed onto particulate matter, which eventually
reliability of the analysis (ATSDR, 2000a).
settles out. Cadmium is produced as a by-product in the
smelting of zinc ores. Annual worldwide production is
estimated at 19 000 tonnes (USGS, 2001b). The princi-
4.4. Heavy metals
pal use of Cd is in the manufacture of nickelcadmium
4.4.1. Arsenic
batteries (75%) (ATSDR, 1999b). Other uses include
Arsenic is the archetypal poison, synonymous with
pigments, coatings and plating, stabilizers for plastic,
homicidal poisoning. The element As is ubiquitous in
and nonferrous alloys.
the environment, associated with mineral deposits of
Cadmium accumulates in aquatic organisms such as
copper, nickel, iron (as arsenopyrite) as well as As oxides
shellfish and crustaceans (Eisler, 1985), as well as in the
and sulfides. Often found as a natural contaminant of
liver and kidney of mammals (e.g., moose, reindeer/cari-
groundwater, it has been responsible for large-scale poi-
bou, deer, and horses) (Crête et al., 1987). Many plants,
soning of human populations in many countries, notably
including tobacco, take up Cd. Uptake is enhanced at
in Bangladesh (Smith et al., 2000) and Taiwan (Tseng,
low soil pH. Occupational exposure results principally
1977). The worldwide production of As is estimated at
from inhalation of dust during manufacturing opera-
39 000 tonnes per year (USGS, 2001a). Atmospheric
tions. Because of the dire health consequences, most
pollution stems mainly from coal burning and the smelt-
countries have implemented strict regulations to control
ing of metals. There is no evidence that Arctic regions
Cd exposure in the workplace (ATSDR, 1999b). Non-
are particularly affected by As contamination.
occupational exposure occurs through the consumption
28
AMAP Assessment 2002: Human Health in the Arctic
of contaminated food (in particular organ meat) and cig-
determination of trace levels of Pb was a problem for
arette smoking. Cadmium blood levels in Arctic pop-
most laboratories. Since then, improved methodology, as
ulations are similar to those in other populations and
well as the generalized use of external proficiency testing
appear to be affected principally by cigarette smoking.
programmes, has resulted in a greatly improved situa-
In an Inuit population from Nunavik, levels in smokers
tion (Weber, 1996).
were 20-fold higher than in non-smokers, ranging from
Even at low levels, Pb affects the peripheral and cen-
4.7 to 6.2 g/L (Benedetti et al., 1992).
tral nervous systems, particularly during their develop-
GFAAS and ICPMS are two techniques of choice
ment. Hence the unborn and young children are particu-
for the determination of Cd in environmental and bio-
larly at risk. Higher exposures result in hematological
logical samples. Although the analytical techniques are
and gastrointestinal symptoms.
straightforward, care must be exercised to avoid con-
tamination during both the sampling phase and labora-
4.4.4. Mercury
tory analysis (ATSDR, 1999b).
Chronic Cd exposure leads to proteinuria and kidney
Mercury exists in many forms in the environment. It is
damage, obstructive lung disease, and osteomalacia, the
present in the atmosphere mainly as a metallic vapor; it
last exemplified by Itai-Itai disease, as observed in
forms different chemical compounds in water, soil and
Japanese populations in the 1960s (Fushukima, 1978).
rock; and it occurs in organic forms, found mainly in liv-
ing organisms. Mercury has a number of unusual prop-
erties. It is the only metal that in elemental form is a liq-
4.4.3. Lead
uid at room temperature. Mercury conducts electricity
Lead has been used for several millennia. Current world-
and it expands linearly with increasing temperature.
wide Pb production is estimated at 3 million tonnes per
Mercury combines easily with most metals, forming al-
year (USGS, 1996), with primary Pb (as opposed to re-
loys known as amalgams, such as those used in dental
cycled Pb) produced by the smelting of Pb sulfide ores.
fillings. These properties have made Hg a widely used
Lead present in the environment is mainly of anthro-
product in household, commercial, medical, and indus-
pogenic origin (Nriagu, 1989). Localized anthropogenic
trial applications. Mercury, in various forms, is also one
sources include Pb smelters, battery recycling plants, and
of the most poisonous natural substances known to hu-
peeling paint from houses and industrial structures.
mans and most other forms of life, making it an effective
Lead-acid battery manufacturing constitutes the princi-
pesticide, fungicide and preservative. Due to its high
pal contemporary use of Pb. Traditional uses such as
toxicity, Hg in the environment has become an issue of
paints, pigments, gasoline additives, ammunition, and
international concern, and this has led many countries
Pb plumbing have all been severely curtailed due to envi-
to implement controls on Hg emissions including phase-
ronmental concerns. Leaded gasoline was a major cause
out of many uses.
of environmental contamination and human exposure
The main ore is cinnabar, with Spain and Italy pro-
during the twentieth century (US EPA, 1991). With the
ducing around 50% of the world's supply of the metal.
phasing out of leaded gasoline in North America in the
Worldwide production of Hg is estimated at 1800
1980s, average blood Pb levels in the population de-
tonnes per year (USGS, 2001c). The metal is widely used
creased by up to 80% (Pirkle et al., 1994). Environmen-
in laboratory work for making thermometers, barome-
tal levels have also decreased significantly as evidenced
ters, diffusion pumps, and many other instruments. It is
for example by a 7.5-fold reduction in the Pb concentra-
used in making mercury-vapor lamps and advertising
tion of Greenland snow (Robinson, 1981).
signs, and in mercury switches and other electronic ap-
Human exposure to Pb may occur through inhala-
paratus. Other uses are in pesticides, mercury cells for
tion of airborne particles, as well as through the diet.
chlor-alkali plants, dental preparations, anti-fouling
Lead is readily absorbed through the lung. Gastroin-
paint, batteries, and catalysts (ATSDR, 1999c).
testinal absorption of Pb is a complex process influenced
Mercury in the environment originates from both
by dietary factors, nutritional status, and the chemical
natural and anthropogenic sources. The former includes
form of the element. Once absorbed into the blood-
degassing of the Earth's crust and geothermal activity.
stream, Pb is distributed into soft tissues and the skele-
Main sources of anthropogenic Hg include the burning
ton, where it accumulates due to its chemical similarity
of coal and losses from chlor-alkali plants. As a result of
to calcium. Lead shot has been implicated as a poten-
environmental concerns, emissions of Hg are declining
tially major source of dietary Pb in Arctic hunter pop-
in Western countries. However, in developing countries
ulations, since significant amounts of Pb fragments
emissions are increasing. The future trend in anthro-
may remain in game, especially birds (Johansen et al.,
pogenic emissions is therefore difficult to predict.
2001). Mean blood concentrations in humans in the
Metallic Hg is practically insoluble in water; it is
range 10 to 50 g/L are reported within the Arctic. Cord
however methylated in sediments by microorganisms.
blood Pb levels in Nunavik were found to be three times
The highly toxic methylmercury (MeHg) thus formed is
higher than in urban Canadian populations (Dewailly
readily taken up by aquatic organisms and biomagnified
et al., 2001a).
through the food chain. Methylmercury exposure has
Lead in environmental and biological samples may
been extensively documented in Arctic and subarctic
be measured by several analytical techniques including
populations since the 1970s (Hansen and Danscher,
GFAAS and ICPMS. The latter technique allows the
1997), notably in Canada (Kosatsky and Dumont, 1991;
measurement of isotopic ratios of Pb, which often yields
Wheatley and Paradis, 1998). In some instances, hair
valuable information as to the source of the metal
was used as a surrogate for blood, and levels were con-
(Gwiazda and Smith, 2000). Prior to the 1980s, accurate
verted using an appropriate conversion factor. Levels
Chapter 4 · Priority Contaminants, `New' Toxic Substances, and Analytical Issues
29
correlate with the consumption of fish or sea mammals.
4.4.6. Tributyltin compounds
In non-consumers, blood values are generally < 2 g/L.
In people who consume large amounts of fish, however,
Tributyltin (TBT) compounds contain three butyl
levels as high as 600 g/L have been observed, with
groups covalently bound to tetravalent tin. The main
means of 20 to 40 g/L. These levels can be compared to
commercial compound is tributyltin oxide, however
the `no risk' level of 20 g/L (WHO, 1990).
tributyltin hydroxide, tributyltin chloride, and tributyl-
The physical and chemical characteristics of Hg
tin carbonate are also found in the environment. The
make it easy to measure and speciate. Analytical prob-
biocide tributyltin oxide is used extensively as an anti-
lems are related to the very low levels found in some
fouling agent in numerous formulations of marine paint.
types of environmental sample and to the complexity of
It is slowly released from the painted surface as the poly-
some matrices (ATSDR, 1999c).
mer is hydrolyzed in seawater, thereby entering the ma-
Methylmercury affects the nervous system and can
rine environment (Champ and Seligman, 1996).
cause paresthesia, ataxia, and tunnel vision. In utero ex-
Because of its low water solubility and lipophilic
posure (as seen in Minamata disease) may result in se-
character, TBT is readily adsorbed onto particles and
vere neurological damage, including cerebral palsy (Ha-
may persist in sediments for several years. It bioaccumu-
rada, 1995). No confirmed diagnosis of MeHg poison-
lates in organisms, with the highest concentrations
ing has been made in Arctic populations.
found in liver and kidney. Uptake from food is more im-
portant than uptake directly from water. However, TBT
is rapidly metabolized and excreted from aquatic and
4.4.5. Selenium
terrestrial mammals and has not been shown to biomag-
Selenium (Se) is a metalloid and the element exists under
nify in higher organisms. TBT has been detected in ma-
three allotropic forms; red, gray and amorphous. Its
rine sediments in harbors throughout the world, includ-
four stable valence states are -2, 0, +4 and +6. In the en-
ing the Arctic region (Chau et al., 1997; Ruiz et al.,
vironment, elemental Se is stable in soil and barely solu-
1996). As a result, most industrialized countries regulate
ble in water. Selenites (+4) and selenates (+6) are soluble
the use of TBT, and its use on vessels shorter than 25 m
in water and thus more bioavailable. Selenates are bio-
is banned. As a consequence, environmental levels have
transformed into organic compounds such as selenome-
decreased steadily since the 1980s. Populations of non-
thionine and selenocysteine, which are subsequently
target affected marine organisms such as snails and mol-
bioaccumulated by aquatic organisms (ATSDR, 1996).
luscs have shown recovery since the regulations were put
Selenium is a relatively rare element, being sixty-
in place (Evans, 1999).
ninth in abundance within the Earth's crust, with an av-
Determination of trace amounts of TBT in water and
erage concentration of 0.05 to 0.09 mg/kg. It is pro-
biota is classically performed by GC after derivatization.
duced as a by-product of the processing of copper ore.
Detection limits are in the sub-ppb range (Sadiki and
Annual worldwide usage is estimated at 1500 tonnes.
Williams, 1996). A novel technique, stir bar sorptive ex-
Much of the Se produced (46%) is used in photocopying
traction with thermal desorption-capillary GCICPMS
for the coating of the transfer cylinders. Other uses in-
allows the determination of ppq-level (i.e., one part in
clude electronics, glassmaking, and pigments. A variety
1015) traces of organotin compounds in environmental
of other uses account for the remaining production.
samples (Vercauteren et al., 2001).
Medically, Se is used as a catalyst in the preparation
TBT is an endocrine disrupter for certain species of
of pharmaceuticals, as an ingredient in antidandruff
snail and other types of mollusc, but has not been shown
shampoos, as a constituent in fungicides, and as a sup-
to similarly affect higher organisms. In humans, acute
plement in animal feeds. Selenium may enter the envi-
exposure to organotin compounds (industrial exposure
ronment as a result of human activity, principally
or laboratory accidents) has led to severe central nerv-
within fly ash resulting from the combustion of coal
ous system damage, as well as to skin irritation (Baaij-
(ATSDR, 1996).
ens, 1986). Although no data were found concerning
The determination of trace amounts of total Se in en-
low-level effects of TBT in humans, in vitro studies using
vironmental and biological matrices can be accom-
human cells indicate potential immunological effects
plished by several techniques including fluorometry
(Whalen et al., 1999). Butyltin compounds were recently
(using 2,3-diaminonaphtalene as a fluorophore), neu-
identified and measured in human blood from Michigan
tron activation, GC (formation of volatile piazselenol),
(Kannan et al., 1999) with total concentrations ranging
AAS (GF or hydride generation) as well as ICPMS
up to 100 g/L.
(ATSDR, 1996). It is often useful to determine which
species of Se, whether organic or inorganic, is present.
4.5. Quality control and quality assurance
Most of the techniques mentioned are, however, not
suitable for this since they require prior mineralization
Reliable and comparable data are the basis for the
of the sample. Coupling HPLC to ICPMS does allow
AMAP assessment. In order to achieve this, a quality as-
the identification and quantitation of individual Se
surance and quality control (QA/QC) programme has
species (Michalke et al., 2001).
been established by the AMAP Human Health Expert
Selenium is an essential element, present in several
Group. This includes guidelines for sampling, trans-
protein systems. It appears to offer protection from
portation and storage, as well as analytical performance
Hg poisoning as indicated by animal experiments
criteria including a ring test programme.
(Cuvin-Aralar and Furness, 1991) and epidemiological
Basic prerequisites must be adhered to if quality is to
studies. However, even a moderate excess of Se can lead
be achieved and maintained. These include competence
to toxicity.
of personnel, adequacy of infrastructure and equipment,
30
AMAP Assessment 2002: Human Health in the Arctic
documentation of all relevant procedures, traceability of
Centre de Toxicologie of the Institute Nationale de Santé
measurements, and calibration. Various legislative bod-
Publique du Québec in Canada has developed QA/QC
ies and international standardization organizations have
activities in support of the AMAP Human Health moni-
promulgated guidelines addressing these requirements.
toring programme. Main activities to date include run-
ISO guide 17025 `General Requirements for the Compe-
ning intercomparison programmes on relevant reference
tence of Calibration and Testing Laboratories' (ISO,
samples based on human material. This includes prepa-
1999) is generally accepted as an appropriate basis for
ration and distribution of test samples, collection and in-
laboratory quality systems. It is however not sufficient
terpretation of data, and the communication of results.
for laboratories to adopt good practices. They must be
In addition to the heavy metals, human samples for the
able to demonstrate conclusively that the data they pro-
organic contaminants (PCBs, standard pesticides, lipids,
duce are consistently reliable.
new organic xenobiotic compounds, and metabolites)
Chemical trace analysis of contaminants in human
will be provided. All laboratories producing data for
samples is challenging. Due to risk of accidental expo-
AMAP are required to participate in the intercompari-
sure to diseases such as HIV, protocols and regulations
son programme and to achieve acceptable results.
concerning sample handling need to be carefully fol-
lowed. Well-designed analytical procedures are required
4.6. Conclusions and recommendations
to overcome the difficulties associated with performing
complex analyses on human media. These may include
Heavy metals and UNEP-listed POPs are of continued
low concentrations of the analytes, small sample vol-
concern for human health and should not be neglected.
ume, a high number of contaminants, blank problems
In addition, increased levels of many `new' POPs and
for compounds still in use, and interfering compounds.
metabolites are a cause of significant concern. However,
For liposoluble compounds, lipid normalization must
more data on their presence and possible effects are
also be performed. To ensure valid results, parameters
needed before their environmental impact, including pos-
such as identification, detection and quantitation limits,
sible implications for human health, can be properly eva-
accuracy and precision, as well as the method's robust-
luated. These knowledge gaps should be addressed in on-
ness must be evaluated. In addition, data treatment, re-
going and future monitoring work. Where relevant, data
porting format and data storage must be harmonized.
reported should be congener-specific and lipid-normalized
A key issue is QC, which incorporates a range of ac-
for the POPs, and speciated for the heavy metals to distin-
tivities such as the establishment and implementation of
guish toxic and non-toxic forms. Selection criteria for
appropriate in-house QA routines, the use of relevant
choosing new target compounds must also be developed.
reference materials, and participation in inter-laboratory
The key component for interpretation of monitoring
comparison programmes (also known variously as profi-
results is reliable and comparable data. Therefore it
ciency testing programmes, external QA schemes, or
is required that all laboratories producing human con-
ring tests). The AMAP Human Health QA/QC system
taminant data for AMAP participate in the AMAP
has been established to accomplish the last. At the re-
Human Health intercomparison programme with ac-
quest of the AMAP Human Health Expert Group, the
ceptable results.