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