analysis of potential carcinogenic contaminants in...

ANALYSIS OF POTENTIAL CARCINOGENIC

CONTAMINANTS IN GRAIN AND

VEGETABLES WITH FOCUS ON HEAVY

METALS

N. Belc, V. Ionescu, M. Ionescu, E. Iorga and G. Mustatea

National R&D Institute for Food Bioresources,

6 Dinu Vintila Street, 021102, Bucharest, Romania

INTRODUCTION

Heavy metals are significant environmental pollutants.

The main cause of emissions of heavy metals into the environment is

represented by anthropogenic activities.

Heavy metals such as arsenic, cadmium, chromium and lead are harmful to

humans and they are known to be potential carcinogens. However, the

mechanism underlying heavy metal - induced cancer remains unclear.

The main objective of this study was to measure the levels of trace elements

(lead, cadmium, chromium and arsenic) knowing to have carcinogenic potential

in 10 plant species (vegetables and grains), and to evaluate them according to

current guidelines in European Union and worldwide.

INTRODUCTION

IARC GHS NTP ACGIH EU

Group 1 Cat. 1A Known A1 Cat. 1

Group 2A Cat . 1B

Reasonably suspected

A2 Cat. 2

Group 2B Cat. 2 A3 Cat. 3

Group 3 A4

Group 4 A5

As & As compounds

Cd & Cd compounds

Cr(VI) compounds

Pb compounds

(inorganic) IARC – International Agency for Research on Cancer (part of WHO); GHS – Globally

Harmonized System; NTP – U.S. National Toxicology Program; ACGIH – American

Conference of Governmental Industrial Hygienists; EU – European Union

Group 1 – The agent is definitely carcinogenic to humans.

Group 2A – The agent is probably carcinogenic to humans.

SAMPLES – The sampling was done in the most unfavorable areas,

sorrounding Bucharest - very crowded, with very heavy traffic and, in

some cases, close to the garbagge collection areas.

1 – 8 14 samples

6 2 samples

1, 6, 8 4 samples

3, 5, 7 19 samples

4, 6, 7 3 samples

3, 5 2 samples

5, 6 2 samples

4, 5, 6 6 samples

4 1 sample

6 1 sample

SAMPLE ANALYSIS

54 samples from 8 areas were analyzed (Ilfov District):

20 cereal samples (14 – wheat, 4 – barley; 2 – oat)

19 tomatoes samples

6 salad samples

3 radishes samples

2 cabbage samples

2 green onion samples

1 spinach sample

1 green garlic sample

Some samples were collected in 2 different periods (May and July 2014)

from the same places, using GPS coordinates.

Samples were dried before being analyzed.

MATERIALS AND METHODS

Samples were weighted into acid-washed PTFE tubes, combined with 3 mL of

ultrapure nitric acid (Merck) and 2 mL of hydrogen peroxide solution 30%

(Merck).

Heating in a microwave digestion system (MWS-2 Berghof).

Microwave digestion steps: 145 ⁰C for 10 minutes, 160 ⁰C for 10 minutes and

190 ⁰C for 20 minutes.

After cooling, each sample was transferred in clean volumetric flasks and the

volumes were increased to 50 mL with ultra pure water (Milli-Q).

All samples were analyzed for Pb, Cd, Cr and As content using a graphite-

furnace atomic absorption spectrometer (AAnalyst 600, Perkin Elmer).

Microwave oven (MWS-2 Berghof) GF-AAS (AAnalyst 600, Perkin Elmer)

RESULTS AND DISCUSSION

Element Domain Correlation

coefficient Slope

Detection

limit

Pb 0 – 80 μg/L 0.99866 0.00196 1.50 μg/L

Cd 0 – 5 μg/L 0.99945 0.07007 0.25 μg/L

Cr 0 – 40 μg/L 0.99967 0.01563 1.30 μg/L

As 0 – 10 μg/L 0.99865 0.00245 1.10 μg/L

Product Pb (mg/kg) Cd (mg/kg) Cr (mg/kg) As (mg/kg)

EU Cod GB Aus EU Cod GB Aus EU Cod GB Aus EU Cod GB Aus

Wheat 0.2 0.2 0.2 0.2 0.2 0.2 0.1 0.1 - - 1.5 - - - 0.2 1.0

Oat 0.2 0.2 0.2 0.2 0.1 - 0.1 - - - 1.5 - - - 0.2 1.0

Barley 0.2 0.2 0.2 0.2 0.1 - 0.1 - - - 1.5 - - - 0.2 1.0

Radish 0.1 0.1 0.1 0.2 0.1 0.1 0.05 0.1 - - 1.0 - - - 0.5 -

Onion 0.1 0.1 0.1 0.2 0.05 0.05 0.05 - - - 1.0 - - - 0.5 -

Garlic 0.1 0.1 0.1 0.2 0.05 0.05 0.05 - - - 1.0 - - - 0.5 -

Tomato 0.1 0.2 0.1 0.2 0.05 0.1 0.05 - - - 1.0 - - - 0.5 -

Cabbage 0.3 0.3 0.3 0.1 0.2 0.2 0.2 0.1 - - 0.5 - - - 0.5 -

Salad 0.3 0.3 0.3 0.1 0.2 0.2 0.2 0.1 - - 0.5 - - - 0.5 -

Spinach 0.3 0.3 0.3 0.1 0.2 0.2 0.2 0.1 - - 0.5 - - - 0.5 -

EU – Regulation (EC) No. 1881/2006; Cod - Codex Alimentarius Commission - Codex STAN 193:1995 2010;

GB - GB 2762 Standard China; Aus - Food Standards Australia and New Zealand - Standard 1.4.1

Parameters of calibration curves

Limits for heavy metals content in EU, China and Australia

Sample

no. Sample

Sampling

area

Collecting

period

Humidity

(%)

Heavy metals content (mg/kg wet weight)

Pb EU

limit Cd

EU

limit Cr As

1 Wheat (1) 1 05.2014 78.6 < 0.002

0.2

< 0.0002 0.2

0.23 0.03

2 Wheat (1) 1 07.2014 45.5 < 0.002 < 0.0002 0.01 < 0.001

3 Barley (2) 1 05.2014 81.1 < 0.002 < 0.0002 0.1 0.07 0.02

4 Wheat (3) 1 07.2014 81.1 < 0.002 < 0.0002

0.2

0.09 0.03

5 Wheat (4) 2 05.2014 82.2 < 0.002 < 0.0002 0.20 0.02

6 Wheat (4) 2 07.2014 46.4 < 0.002 < 0.0002 < 0.0013 < 0.001

7 Wheat (10) 5 05.2014 82.0 < 0.002 < 0.0002 0.01 0.04

8 Wheat (15) 4 05.2014 79.7 < 0.002 < 0.0002 < 0.0013 0.01

9 Wheat (16) 3 05.2014 78.0 < 0.002 < 0.0002 < 0.0013 0.04

10 Oat (24) 6 05.2014 85.8 0.04 < 0.0002

0.1

0.17 0.01

11 Oat (24) 6 07.2014 75.1 < 0.0002 < 0.0002 < 0.0013 0.02

12 Barley (25) 6 05.2014 76.1 0.68 < 0.0002 0.12 0.02

13 Barley (25) 6 07.2014 10.8 < 0.002 < 0.0002 0.01 0.01

14 Wheat (26) 6 05.2014 78.8 < 0.002 < 0.0002 0.2

0.18 0.01

15 Wheat (26) 6 07.2014 50.2 < 0.002 < 0.0002 < 0.0013 < 0.001

16 Barley (27) 8 05.2014 81.0 < 0.002 < 0.0002 0.1 0.17 0.01

17 Wheat (28) 8 05.2014 79.0 < 0.002 < 0.0002

0.2

0.10 0.02

18 Wheat (29) 7 05.2014 82.2 < 0.002 < 0.0002 0.25 0.01

19 Wheat (29) 7 07.2014 11.1 < 0.002 < 0.0002 < 0.0013 0.02

20 Wheat (32) 7 05.2014 79.7 < 0.002 < 0.0002 0.05 0.02

Heavy metals content of grain samples

Lead content of all cereal samples is bellow 0.2 mg/kg limit stated by

Regulation (EC) No. 1881/2006.

Cadmium content of all cereal samples is bellow 0.2 mg/kg limit (for wheat)

and 0.1 mg/kg limit (for barley and oat) stated by Regulation (EC) No.

1881/2006.

For Chromium and Arsenic there is no imposed limit in EU. The level of

these two metals in all tested cereal samples is bellow 1.5 mg/kg (for

Chromium) and 0.2 mg/kg (for Arsenic), limits stated by GB 2762 Standard

(China).

According with the heavy metal levels in analyzed cereals the

descendent order was:

Wheat: Crt > As > Pb > Cd

Oat: Crt > As > Pb > Cd

Barley: Pb > Crt > As > Cd

Sample

no. Sample

Sampling

area

Collecting

period

Humidity

(%)


Pb EU

limit Cd

EU

limit Cr As

1 Tomato (5) - leaves 5 05.2014 88.8 0.3

0.1

0.01

0.05

0.14 0.08

2 Tomato (5) – unriped fruits 5 05.2014 91.7 < 0.002 < 0.0002 0.12 0.03

3 Tomato (5) – riped fruits 5 07.2014 92.2 < 0.002 < 0.0002 < 0.0013 0.02

4 Tomato (5) – peel 5 - - < 0.002 < 0.0002 < 0.0013 < 0.001

5 Tomato (5) - juice 5 - - < 0.002 < 0.0002 0.01 < 0.001



8 Tomato (7) – leaves 5 05.2014 88.6 < 0.002 < 0.0002 0.09 0.06

9 Tomato (7) – riped fruits 5 07.2014 93.5 0.01 < 0.0002 0.02 0.01

10 Tomato (8) - leaves 5 05.2014 88.9 < 0.002 < 0.0002 0.03 0.06



13 Tomato (8) – peel 5 - - < 0.002 < 0.0002 < 0.001 < 0.001

14 Tomato (8) - juice 5 - - < 0.002 < 0.0002 0.02 < 0.001

15 Tomato (9) – leaves 5 05.2014 88.2 < 0.002 < 0.0002 0.01 0.05


17 Tomato (17) – leaves &

fruits

3 05.2014 88.4 < 0.002 < 0.0002 < 0.0013 0.01

18 Tomato (30) – leaves 7 05.2014 87.8 < 0.002 < 0.0002 0.12 0.04

19 Tomato (30) – unripe fruits 7 05.2014 92.6 < 0.002 < 0.0002 < 0.001 0.02

Heavy metals content of tomatoes samples

Lead and Cadmium content of all tomatoe samples is bellow 0.1 mg/kg and

0.05 mg/kg, respectively, limits stated by Regulation (EC) No. 1881/2006.

For Chromium and Arsenic there is no imposed limit in EU. The level of

these two metals in all tested cereal samples is bellow 1.0 mg/kg (for

Chromium) and 0.5 mg/kg (for Arsenic), limits stated by GB 2762 Standard

(China).

Heavy metals content in leaves is higher than in fruit tomatoes.

The descendent order of heavy metals level in analyzed tomatoes was:

Leaves: Pb > Crt > As > Cd

Unriped tomatoes: Crt > As > Pb > Cd

Riped tomatoes: As > Crt > Pb > Cd

Sample

no. Sample

Sampling

period

Sampling

area

Humidity

(%)


Pb EU

limit Cd

EU

limit Cr As

1 Salad (11) 05.2014 5 93.6 0.02

0.3

0.01

0.2

0.07 0.02

2 Cabbage (12) 05.2014 5 91.0 < 0.002 < 0.0002 0.01 0.04

3 Salad (13) 05.2014 5 90.2 < 0.002 0.02 < 0.0013 0.03

4 Green onion (14) 05.2014 5 90.7 < 0.002 0.1 < 0.0002 0.05 < 0.0013 0.03

5 Salad (18) 05.2014 3 96.5 < 0.002

0.3

< 0.0002

0.2

0.03 0.03

6 Cabbage (19) 05.2014 3 87.7 < 0.002 < 0.0002 < 0.0013 0.01

7 Spinach (20) 05.2014 6 91.3 < 0.002 0.01 0.02 0.01

8 Radish (21) 05.2014 6 95.4 < 0.002 0.1

< 0.0002 0.1 0.03 0.01

9 Green onion (22) 05.2014 6 91.2 < 0.002 < 0.0002 0.05 0.01 0.02

10 Salad (23) 05.2014 6 92.3 0.2 0.3

0.01 0.2

0.09 0.04

11 Salad (23) 05.2014 6 93.4 0.04 < 0.0002 0.37 0.03

12 Radish (31) 05.2014 7 95.3 < 0.002 0.1

< 0.0002 0.1

0.08 < 0.001

13 Radish (33) 05.2014 4 93.5 < 0.002 < 0.0002 < 0.0013 0.03

14 Salad (34) 05.2014 4 94.4 < 0.002 0.3 0.03 0.2 0.02 0.05

15 Green garlic (35) 05.2014 4 77.2 < 0.002 0.1 0.01 0.05 < 0.0013 0.03

Heavy metals content of vegetables samples

Lead content of radish, onion and garlic samples is bellow 0.1 mg/kg limit and

the lead content of cabbage, salad and spinach samples is bellow 0.3 mg/kg limit,

stated by Regulation (EC) No. 1881/2006.

Cadmium content for all tested vegetables samples is bellow limits stated by

Regulation (EC) No. 1881/2006: 0.1 mg/kg for radish, 0.05 mg/kg for onion and

garlic and 0.2 mg/kg for cabbage, salad and spinach.

For Chromium and Arsenic there is no imposed limit in EU. The level of these

two metals in all tested vegetables samples is bellow 1.0 mg/kg (for Chromium in

radish, onion and garlic) and 0.5 mg/kg (for Arsenic and Chromium in cabbage,

salad and spinach), limits stated by GB 2762 Standard (China).

The descendent order of heavy metals level in the analyzed vegetables was:

Salad: Crt > Pb > As > Cd

Green onion: As > Crt > Pb > Cd

Radish: Crt > As > Pb > Cd

Cabbage: As > Crt > Pb > Cd

Spinach: Crt > As = Cd > Pb

Green garlic: As > Cd > Pb > Crt

CONCLUSSIONS (I)

Heavy metals content (lead, cadmium, total chromium and arsenic) was

determined from 10 plant species (cereals: wheat, oat and barley and

vegetables: tomatoes, radish, cabbage, green onion, spinach, salad and green

garlic) collected from 8 areas located sorrounding Bucharest.

Samples were collected from the most unfavorable area considering a high

potential of chemical contamination.

The sampling was done in two different period of the year (May and July)

from the same place, using GPS coordinates.

Samples were analyzed after drying and microwave digestion using atomic

absorption spectrometry technique (GF-AAS).

CONCLUSSIONS (II)

Heavy metals contamination of cereals and vegetables cannot be

underestimated as these foodstuffs are very important components of human diet.

Vegetables take up metals by absorbing them from contaminated soils, as well

as from deposits on different parts of the vegetables exposed to the air from

polluted environment, so regular monitoring of these metals in vegetables is

essential.

Although the content of lead and cadmium in cereals was very low (taking as a

sample entire plant), it is also necessary to be analysed only the grain because

they are used in feed and food industry.

Leafy vegetables (especially salad) had proved to had the highest content of

heavy metals (even if it was bellow the limits).

No contamination was found in all tested samples.

PERSPECTIVES

Analysis of heavy metals contamination on the entire food chain: soil,

water and plant is needed.

Extending the analyses to other potential carcinogenic contaminants

along the food chain will be envisaged.

Understanding the way of accumulation in order to find prevention

measures that can be taken into account.

Developing of new and more efficient safety management tools.

Considering chemical contamination of food as a “hidden contamination”

that it can’t be seen or tasted, the perspectives in the future are related to

discovering/innovation of the new tools in order to control/monitor the

level of the most toxicogenic chemical contaminants and assure food

safety.

So, the perspectives can be:

Gabriel Mustatea, PhD [email protected]

Nastasia Belc, PhD [email protected]

mailto:[email protected]

mailto:[email protected]

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