semi-volatile organic pollutants: sources and occurrence in food
TRANSCRIPT
Semi-volatile organic pollutants: sources and occurrence in food and the environment
Prof. Dr. Biljana ŠkrbićNataša Đurišić-Mladenović
University of Novi Sad, Faculty of Technology Centre of Excellence in Food Safety and Emerging RisksNovi Sad, Serbia
5th CEFSER Training Course Analysis of chemical contaminants in food and the environment7-11 May 2012
Semi-volatile organic pollutants or compounds (SVOCs)
belong to different chemical
classes,
with many of them classified
as
Persistent Organic Pollutants
(POPs) or
Peristent Toxic Substances
(PTSs)
Some chemical classes belonging to
SVOCs are:
polychlorinated biphenyls (PCBs),
organochlorine pesticides (OCPs),
polycyclic aromatic hydrocarbons (PAHs),
polychlorinated dibenzo-p-dioxins
(PCDD), and dibenzofurans (PCDFs), etc.
These organic compounds are
resistant to environmental degradation
through chemical, biological, and photolytic
processes.
Because of this, they have been observed to…
persist in the environment, transfer long distances from the
emission sources, bioaccumulate in organisms,
leading to the biomagnification in food chains, and
have impacts on the environment and human health with a very broad spectrum of harmfull
effects.
These are also the main properties of SVOCs
including those officially classified as priority
POPs by the United Nations Environmental
Programme under the Stockholm Convention.
12 Stockholm (old) POPs
Pesticide Industrial Chemical By-productAldrin +Chlordane +DDT +Dieldrin +Endrin +Heptachlor +Mirex +Toxaphene +Hexachlorobenzene + + +PCB + +PCDD +PCDF +
Stockholm Convention criteria for POPs‘ persistency
In order to classify a chemical as POP, evidence of its prolonged half-life in different environmental
compartment should exist:
Half time in water > 2 months
Half time in soil > 6 months
Half time in sediments > 6 months
POPs‘ potential for long-range environmental transport
has a potential for long-range
environmental transport through air
and water, that could lead to its
deposition in a receiving environment
distant from the sources of the
release.
One of the criteria to include a compound into the POPs
group, is that the monitoring data, environmental fate
properties and/or model results should demonstrate that it
Chemicals are semi-volatile
Evaporate over warmer regions and condense in colderatmospheres
Widespreaddistribution
Can affect regionswhere use is non-existent
Transboundary Movement of SVOCs (POPs) through GLOBAL DISTILLATION phenomenon
• their concentration is gradually built up over time in a living organism, because they cannot be broken down for use by the organism (that is, these chemical cannot be metabolized), •leading to the biomagnification – the process through which higher concentrations of these pollutants are reached in organisms higher up in the food chain, generally through a series of prey-predator relationships.
POPs‘ potential to bioaccumulate
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Amounts (medians) of indicator PCBs in human milk from various countries
POPs show adverse effects to human health
or to the environment.
POPs‘ toxicity
After these pollutants are put into the environment, they are able to stay in the system for decades
causing problems such as cancer, birth defects, learning disabilities,
immunological, behavioral, neurological and reproductive discrepancies in human and other
animal species.
Endocrine Disruptor Chemicals (EDCs)
Public concern about contamination by POPs increased recently because several of these
compounds are identified as hormone disrupters (EDC), which can alter normal function of endocrine and reproductive systems in humans and wildlife.
POPs enter the environment through
different routes, either through point or
diffuse sources during their
production, use or after disposal.
There is also a possibility for their unintentional
production when they are accidentally formed or
released as a byproduct from various activities, such as
industrial or diverse combustion processes
(e.g. PCDDs/PCDFs, PAHs).
POPs
Intentionally Unintentionally
Industrial chemicals (e.g.PCB)
OCPs PAHs Dioxins Furans
The atmosphere often plays a key role in the SVOCs transport within the immediate vicinity of the sources as
well as over great distances.
Finally, they are DEPOSITED in different environmental compartments (water, soil, biota) through
dry or wet deposition.
SVOCs are HYDROPHOBIC ORGANIC CHEMICALS,
which once released in the environment
tend to bind to the organic fraction
either in soil, dust, and sediment particles, and to
accumulate in animals and humans.
AIR-TO-PLANT TRANSFER of SVOCs
is the first step in terrestrial food chain accumulation,
and therefore a starting point for transfer of these
compounds to animals and humans.
AGRICULTURAL PLANTSare of particular interest because they are a
key link in the chain atmosphere-food being used as feed, introducing the SVOCs to an
animal milk and meat, which consumption accounts for much of background human exposure to
persistent lipophilic organic pollutants.
oPOLYCHLORINATED BIPHENYLS (PCBs)
oORGANOCHLORINE PESTICIDES (OCPs)
oPOLYCYCLIC AROMATIC HYDROCARBONS (PAHs)
PCBs are man-made chemicals
synthesized with different chlorination
degrees.
Although theoretically 209
congeners are possible,
the actual number of PCB
compounds (congeners)
found in the environment
is much lower.
THE MOST IMPORTANT
TO MONITOR IN THE
ENVIRONMENT AND
FOOD are:
12 congeners that show toxicological
properties similar to 2,3,7,8- tetrachlorodibenzo-p-
dioxin (TCDD), representing one of the most toxic
contaminant known, and, therefore, termed
‘‘dioxin-like PCBs’’.
Their toxic effects include immuno- and reproductive toxicity, carcinogenic potency, negative influence on the
development of central nervous system, etc.
TCDD
The other group of PCBs – ‘‘non-dioxin-like’’ – do not show dioxin-like toxicity but have another toxicological profile, acting on the
central nervous system, the thyroid and the endocrine system after high incidental intakes or after bio-accumulation in the body upon long-term
intake.
Six of them (PCB 28, 52, 101, 138, 153 and 180), the so-called ‘‘INDICATOR PCBs’’, are most commonly determined
in the environment as they are frequently the most abundant in
various environmental matrices andcover a wide range of chlorination (from 3 to 7
chlorine atoms).
It has been found that more than 90% of the total daily
intake of these contaminants is derived from food with
inhalation contributing the majority of the remainder.
EXPOSURE
The HIGHEST LEVELS of most persistent pollutants were
observed in
food of animal origin
but there is growing evidence that
cereals and vegetables
could be the PREDOMINANT SOURCES of PCBs for
humans.
Several countries, such as France, the Netherlands, UK, Germany, USA and Canada,
have defined maximum tolerances of PCBs in some edible products.
These tolerances are expressed as total content of investigated PCBs and are based on specific
congeners, primarily on dioxin-like congeners.
Form for reporting of congener-specific analytical results of non-dioxine-like PCBs in food
28, 52, 101, 138, 153, 180-sum PCB-6
oPOLYCHLORINATED BIPHENYLS (PCBs)
oORGANOCHLORINE PESTICIDES (OCPs)
oPOLYCYCLIC AROMATIC HYDROCARBONS (PAHs)
OCPs are a diverse group of chlorinated
contaminants that have been used as
pesticides.
DDT is probably best known for its dual nature: although remarkably effective in destroying certain living things that are harmful to plants and animals, it can also be extremely dangerous to humans and the environment.
After some OCPs were banned for use since the 80s,
common daily food items such as eggs, milk, poultry, meat
and fish have been used for monitoring the residual levels of
OCPs, as the major source of human background exposure
to OCPs is through food of animal origin.
As regards food of animal origin,
one efficient way to avoid large-scale contamination is
to control and monitor the level of
OCP residues present in animal feeds
before being fed to the husbandry animals.
To ensure that pesticide residues are not found in food or feed at levels presenting an unacceptable risk for
human consumption, maximum residue levels (MRLs)
have therefore been set by the European Commission and also by other international authorities (EPA, Codex
Alimentarius).
MRLs are set for a wide range of food commodities of plant and animal origin, and
they usually apply to the product as placed on the market.
http://ec.europa.eu/sanco_pesticides/public/index.cfm
Data sets on pesticides’ MRLs are available online, including the MRLs set by EC:
oPOLYCHLORINATED BIPHENYLS (PCBs)
oORGANOCHLORINE PESTICIDES (OCPs)
oPOLYCYCLIC AROMATIC HYDROCARBONS (PAHs)
Polycyclic aromatic hydrocarbons (PAHs) are fused-ring aromatic compounds formed in incomplete combustion of organic material during a number of activities (automobile exhausts, domestic heating, biomass burning, industrial activities, oil spillage, etc.).
PAHs generally are found throughout the environment in air, water and soils in the form of COMPLEX MIXTURES, never as
individual compounds.
In general, the composition of PAH profiles varies depending on the source (combustion conditions) and the
environmental compartment.
Since there is no international agreement on which panel of individual PAHs should be analyzed and reported
in order to characterize distinct emission sources, PAH lists released from different organizations do contain
different compounds.
Sixteen different PAHs are prioritized by the US-
Environmental Protection Agency (EPA) and also
by the European Commission.
European Commission list consists of 16 individual PAHs as being major concern for human health, while
EPA listed also some of lower molecular-weight PAHs such as naphthalene, phenanthrene, anthracene, or fluoranthene
due to their occurrence in environmental samples.
In order to distinguish the set of PAHs listed by EC from a set of also 16 compounds that has been addressed by the US
EPA, known as 16 EPA PAHs,
the terminology 15+1 EU priority PAHs was chosen.
A number of PAHs have been shown to be genotoxic carcinogens.
From all hydrocarbons detectable in the human environment the most intensively studied
species, is benzo[a]pyrene classified by the International Agency for Research on Cancer
(IARC) as a probable human carcinogen, and it has been traditionally used as indicator of
carcinogenic PAHs.
For non-smoking humans, the major routes of exposure to PAH are from
food and to some extent from inhaled air.
Food can be contaminated by:
(i) environmental PAHs that are present in air, soil or water;
(ii) industrial food processing methods; and(iii) home food preparation.
PAHs have been detected in a variety of foods,
notably vegetables as a result of the deposition of
airborne PAHs, and in fish and mussels from
contaminated waters.
The waxy surface of vegetables and fruits can concentrate low molecular mass PAHs through surface adsorption and particle-bound
high molecular mass PAHs can contaminate the surface due to atmospheric fallout.
PAHs can also contaminate foods during industrial
smoking, heating and drying processes that allow
combustion products to come into direct contact
with food.
Contamination of cereals and of vegetable oils (including seed oils and olive residue oils) with PAH usually occurs
during technological processes like direct fire drying, where combustion products may come into contact with the grain,
oil seeds or the oil.
PAHs could be also formed as a result of certain food
preparation methods, such as grilling, roasting and smoking.
The highest PAH concentrations are usually found in
grilled/barbecued foods (especially meat and meat products
grilled under prolonged and severe conditions), foods
smoked by traditional techniques (fish in particular), and
mussels and other seafood from polluted waters.
http://ec.europa.eu/food/fs/sc/scf/out154_en.pdf
Smoked and grilled food may contribute significantly to the intake of PAHs if such foods are a large part
of the usual diet.
However, generally the major contributors to PAH intake in the average diet are oils and fats, cereals, fruits and
vegetables, due to their higher consumption rates.
Maximum levels of benzo(a)pyrene in different food commodities are specified in EC
Regulation 1881/2006
Foodstuffs Maximum levels
(μg/kg wet weight)
Oils and fats (excluding cocoa butter) intended for direct human consumption or use as an ingredient in foods
2.0
Smoked meats and smoked meat products 5.0Muscle meat of smoked fish and smoked fishery products, excluding bivalve molluscs. The maximum level applies to smoked crustaceans, excluding the brown meat of crab and axcluding head and thorax meat of lobster and similar large crustaceans (Nephropidae and Palinuridae)
5.0
Muscle meat of fish, other than smoked fish 2.0Crustaceans, cephalopods, other than smoked. The maximum level applies to crustaceans, excluding the brown meat of crab and axcludinghead and thorax meat of lobster and similar large crustaceans (Nephropidae and Palinuridae)
5.0
Bivalve molluscs 10.0Processed cereal-based foods and baby foods for infants and young children
1.0
Infant formulae and follo-on formulae, including infant milk and follow-onmilk
1.0
Dietary foods for special medical purposes intended specifically for infants 1.0
However, European Food Safety Authority (EFSA)
adopted an opinion on PAHs in food on 9 June 2008,
according to which benzo(a)pyrene is not a suitable
marker for the occurrence of PAHs in food…
… and that a system of four specific substances
(PAH4) or eight specific substances (PAH8) would
be the most suitable indicators of PAHs in food.
EFSA also concluded that a system of eight
substances (PAH8: benz(a)anthracene,
benzo(b)fluoranthene, benzo(k)fluoranthene,
benzo(ghi)perylene,
chrysene, dibenz(a,h)anthracene and indeno(1,2,3-
cd)pyrene)
would not provide much added value compared to a
system of four substances (PAH4).
Thus, based on the conclusions of EFSA, the
current system of using benzo(a)pyrene as
the only marker for the group of PAHs has
not been maintained.
New maximum levels for the sum of four substances
(PAH4)
is introduced, whilst maintaining a separate
maximum level for benzo(a)pyrene in the latest
EC Regulation 835/2011
which shall apply from September 1, 2012.
The separate maximum level for
benzo(a)pyrene is maintained to ensure
comparability of previous and future data.
After a certain time of implementation of this
amendment and on basis of new data that
will be generated in future, the need for
retaining a separate maximum level for
benzo(a)pyrene should be readdressed.
This new system of the indicator PAH4
group would ensure that PAH levels in food
are kept at levels that do not cause health
concern and that the amount of PAHs can
also be controlled in those samples in which
benzo(a)pyrene is not detectable, but where
other PAHs are present.
As regards the sum of PAH4, lower bound
concentration should be used as the basis for
compliance decisions, which means
concentrations of undetected compounds
should be considered to be 0.
Foodstuffs “OLD” maximum levels
(μg/kg wet weight)1881/2006
“NEW” maximum levels (μg/kg)
835/2011
Benzo(a)pyrene Benzo(a)pyrene Sum of benzo(a)pyrene,
benz(a)anthracene,benzo(b)fluoranthen
e and chryseneOils and fats (excluding cocoa butter) intended for direct human consumption or use as an ingredient in foods
2.0 2.0 10.0
Smoked meats and smoked meat products
5.0 5.0 until 31.8.2014
2.0 as from 1.9.2014
30.0 as from 1.9.2012 until
31.8.201412.0 as from
1.9.2014
Data for smoked meat and fish have shown that
the lower maximum levels are achievable.
Still, adaptations of current smoking technology
may be necessary in some cases.
Therefore, a two step procedure should be
established for smoked meat and fish, which
grants a transition of two years from the date of
application of this Regulation before lower
maximum levels become applicable.
Foodstuffs “OLD” Maximum
levels (μg/kg wet weight)1881/2006
“NEW” maximum levels (μg/kg)835/2011
Benzo(a)pyrene Benzo(a)pyrene Sum of benzo(a)pyrene,
benz(a)anthracene,benzo(b)fluoranthene
and chrysene
Muscle meat of smoked fish and smoked fishery products, excluding smoked sprats, canned smoked sprats, bivalve molluscs, heat treated meat and heat treated meat products. The maximum level for smoked crustaceans applies to muscle mat from appendages and abdomen. In case of smoked crabs and crab-like crustaceans (Brachyura and Anomura) it applies to muscle meat from appendages
5.0 5.0 until 31.8.2014
2.0 as from 1.9.2014
30.0 as from 1.9.2012 until
31.8.2014
12.0 as from 1.9.2014
Foodstuffs “OLD” Maximum levels (μg/kg wet
weight)1881/2006
“NEW” maximum levels (μg/kg)835/2011
Benzo(a)pyrene Benzo(a)pyrene
Sum of benzo(a)pyrene,
benz(a)anthracene,benzo(b)fluoranthene
and chrysene
Bivalve molluscs smoked 10.0 6.0 35.0Processed cereal-based foods and baby foods for infants and young children
1.0 1.0 1.0
Infant formulae and follo-on formulae, including infant milk and follow-onmilk
1.0 1.0 1.0
Dietary foods for special medical purposes intended specifically for infants
1.0 1.0 1.0
NEW FOOD COMMODITIES IN REGULATION ON PAHs
• COCOA BUTTER and derived products• COCONUT OIL intended for direct human consumption or use as an ingredient in food
• SMOKED SPRATS AND CANNED SMOKED
SPRATS
• BIVALVE MOLLUSCS (fresh, chilled, or frozen);
• HEAT TREATED MEAT AND HEAT TREATED
MEAT PRODUCTS SOLD TO THE FINAL
CONSUMER
COCOA BUTTER contains higher levels of
PAHs than other oils and fats, mainly due to
inappropriate drying practice of the cocoa
beans and the fact that cocoa butter can not be
refined as other vegetable oils and fats.
Cocoa butter is a main constituent of cocoa
raw products (e.g. cocoa beans, cocoa mass,
nibs or liquor) and is present in chocolate and
other cocoa products often consumed by
children.
It is therefore necessary to establish maximum
levels for PAHs in cocoa beans and derived
products, including cocoa butter.
Smoked sprats and canned smoked sprats
have been found to contain higher levels of
PAHs than other smoked fish, which is the
reason why specific maximum levels is
established for these type of commodities in
order to reflect what is achievable in such
foodstuffs.
High levels of PAHs have been found in some types
of heat treated meat or meat products sold to final
consumer.
These levels are avoidable of appropriate
processing conditions and equipment are used.
It is therefore appropriate to establish maximum
levels for PAHs in meat and meat products that have
undergone a heat treatment process known to
potentially results in formation of PAHs, i.e. only
grilling and berbecuing.
Foodstuffs “OLD” Maximum
levels (μg/kg wet weight)1881/2006
“NEW” maximum levels (μg/kg)835/2011
Benzo(a)pyrene Benzo(a)pyrene Sum of benzo(a)pyrene,
benz(a)anthracene,benzo(b)fluoranthene
and chryseneCocoa beans and derived products
5.0 μg/kg fat as from 1.4.2013
35.0 μg/kg fat as from 1.4.2013 until
31.3.201530.0 μg/kg fat as
from 1.4.2015Coconut oil intended for direct human consumption or use as an ingredient in food
2.0 20.0
Smoked sprats and canned smoked sprats (sprattus sprattus);bivalve molluscs (fresh, chilled, or frozen); heat treated mean and heat treated meat products sold to the final consumer
5.0 30.0
ANALYSIS OF SVOCs
In general, the analysis of organic contaminants in food and environmental samples is not an easy task due to
many interfering compounds present in large quantities in comparison to low levels of the contaminants.
The challenge for SVOCs analysts is to maximize their recoveries and minimize the interferences by proper
extraction and clean-up procedures and also using the selective/specific/sensitive instrumental techniques.
M.S. El-Shahawi et al. / Talanta 80 (2010) 1587–1597
“Classical” methods for determination of SVOCs consist of extraction and clean up and they are time
consuming and use large quantities of organic solvents
The latest trend is to MINIMISE:
the number of manipulations,
the solvent volumes, the number of
evaporation steps, the use of toxic
solvents,to automate the
preparation step as far as possible.
It is developed originally as sample preparation technique for multiresidue analysis of pesticide,
but now its application scope has been broaden towards POPs, mycotoxins and other organic pollutants.
M.S. El-Shahawi et al. / Talanta 80 (2010) 1587–1597
UHPLC-APPI-MS-MS PAHs
SVOCs have been the subject of the research in CEFSER Lab for many years resulting in articles published in international journals,
concerning either food safety or the environmental issues…
“Toxic and very long-lasting, persistent organic pollutants endanger the well-being of our planet and all living beings, (...)
Only decades ago, most of the 12 POPs targeted for international action under the treaty being negotiated did not exist, and now they are in the air, water, soil around the planet and in us all, and they last for generations,....”
UNEP Press Release (2000): Klaus Töpfer, Executive Director of the United Nations Environment Programme (UNEP), Speech held on the 10th of November 2000, UNEP, Nairobi/ Geneva
5th CEFSER Training Course Analysis of chemical contaminants in food and the environment7-11 May 2012