The case of CS2 : from Official Controls at the · Complex Residue Definitions can trigger...

Complex Residue Definitions can trigger difficulties inRisk Assessment studies :the CS2 case

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DirectorDr. Popi Kanari

Despo Christodoulou ,Head ofPesticide Residues Lab

The case of CS2 : from Official Controls at the

State General Laboratory – Ministry of Health-Cyprus

59th Adv.Forum Meeting

State General Laboratory

Number of analysed samples for Pesticide Residues for2010 adjusted on the number of population for each

member state59th Adv.Forum Meeting

EPRW 2016Limassol

23-27 of May 2016 ,CyprusNational Coordinator/Organiser

State General LaboratoryMinistry of Health

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SubscribeS e a rc h

The Pesticide Residues Laboratory of theState General Laboratory –Cyprus

The National Reference Laboratory (NRL)

being

• Cereals

• Fruits and Vegetables

• Products of animal Origin

• Single methods applied

also to Dithiocarbamates

as RD

(accredited by the Greek Accreditation body ESYD since 2002 according toEN / ISO / IEC 17025)


Dithiocarbamates

Chemicals used as Fungicides


Dithiocarbamates (dithiocarbamates expressed as CS2, including maneb,

mancozeb, metiram, propineb, thiram and ziram)

Official SRM method applied in routine analysis:

Chemical cleavage ,by hydrolysis ,of Dithiocarbamates into Carbon Disulphide,and then determining it by GC-FPD.

In case of positive samples (in particular in cases of violating samples) the following mustbe conidered

• ensure that the samples do not contain naturally S-Compounds which canproduce endogenous CS2

• Interferences are known from Natural Precursors eg from Brassica that canthemselves produce CS2 during Hydrolysis

• CS2 is used by itself (not as Dithiocarbamates )as a fumigant in cereals

• Samples treated with Dithiocarbamates will not only contain intactDithiocarbamates but may also have free CS2.

• Apart from the compounds within the definition of the RD, CS2 mightoriginate from other Dithiocarbamates


Difficulties in evaluation of positive samplesin particular in cases of violating samples

Evaluation of the results is difficult since

• No MRLs for free CS2

• Very difficult to analyse the components of the RDindividually ( dithiocarbamates are very fragile, no officialmethods for all components)

• No MRLs for all individual components(Dithiocarbamates )

How to perform Risk Assessment?

• No Toxicological Data for CS2

• Available Toxicological Data for only some individualcomponents of the RD


No Toxicological information for Carbon Disulphide


How to perform a risk assessment in cases of

Dithiocarbamates expressed as CS2?

A real case example with spinach using the PRIMOmodel:with these values below no real concern

ADI ARfD % ARfD

mg/kg bw/day mg/kg bw/day Children Adults

Pesticide: CS2 Ziram

Amount mg/kg 1,2 2,4 0,006 0,08 67,8 26,8

Propineb

MRL mg/kg 0,05 2,3 0,007 0,1 52,0 20,6

Maneb

2,1 0,05 0,2 23,7 9,4

Mancozeb

2,14 0,05 0,6 8,1 3,2

Thiram

1,9 0,01 0,6 7,2 2,8

Metiram

2,1 0,03 0,16 29,7 11,7

Spinach


How to perform a risk assessment in cases ofDithiocarbamates expressed as CS2?

Using the PRIMO MODEL

ADI ARfD % ARfD

mg/kg bw/day mg/kg bw/day Children Adults

Pesticide: CS2 Ziram

Amount mg/kg 7,6 15,3 0,006 0,08 276,3 149,6

Propineb

MRL mg/kg 1,0 14,5 0,007 0,1 209,5 113,4

Maneb

13,3 0,05 0,2 96,1 52,0

Mancozeb

13,56 0,05 0,6 32,7 17,7

Thiram

12,0 0,01 0,6 28,9 15,6

Metiram

13,6 0,03 0,16 122,8 66,5

Wheat


A real case example with imported wheat ; With thesevalues below there is concern from possible 3

Dithiocarbamates

Evaluation of the Results of the Wheat sample

Where could CS2, in wheat , originate from ?

from Fumigant CS2 ?

from any of THE 6 DITHIOCARBAMATES and (others not included in thedefinition )or any Combination of them ?

From a combination possibly of the fumigant CS2 and any of theDITHIOCARBAMATES ?

So all these possibilities should be investigated so as to carry outRisk Assessment on CS2


Evaluation and Risk Assessment studies: the CS2 case

Further Steps taken to shed light on the case and facilitate therisk assessment process

.analysis for the Dithiocarbamates expressed as CS2 wasRepeated

The sample was analysed with SRM method for thedetermination of ETU and PTU metabolites

ETU was detected/PTU not detectedAs this was a case of Scientific interest it was sent to EURL

Analysis at the EURL-SRM a)Results of Dithiocarbamates expressed as CS2were confirmed b) Analysis for free CS2 showed very low concentrations ofCS2 ……


Metabolites that could give information on the origin ofthe CS2 AFTER CLEAVAGE


Evaluation of the Results of the Wheat sample

Summing up of evaluation of results for CS2 which has been measuredafter in situ Chemical cleavage of Dithiocarbamates in the Lab

Dithiocarbamates

Probinem ,Mancozeb,Maneb ,Thiram and Metineb

have as a metabolite ……… ……. ETU

Dithiocarbamate

Probinem

has a metabolite ………………………..PTU

Dithiocarbamate

Ziram has a metabolite …………………..CS2

ETU was detected/PTU not detected

So all these possibilities should be investigated so as to carry outRisk Assessment on CS2


Risk Assessment studies: the CS2 case

One knows from which Dithiocarbamate or Combination of these themeasured CS2 originated from

the measured CS2 originated from the fumigant CS2 or a Combination ofthe fumigant CS2 with one or more Dithiocarbamates

This raises again difficulties as there are no toxicological data for CS2and no toxicological data for all Dithiocarbamates to carry out

Risk Assessment

Risk Assessment on the Wheat sample can only be carried out if


Evaluation and Risk Assessment studies: the CS2 case

The Wheat case with CS2

So it could be a combination of the Fumigant CS2 and Dithiocarbamate/s(NEBAM,METIRAM,MANEB,MANCOZEB) OR a combination of them

It could not be from ZIRAM as ETU was detected and ZIRAM does nothave ETU as a Metabolite

It could be from other Dithiocarbamates outside the scope of thedefinition of RD of Dithiocarbamates


The risk assessment for the Imported wheat wasinconclusiveTherefore it seems that:

• More work has to be done on risk assessmentfor complex RDs like Dithiocarbamates

• MRLs & Toxicological Data for CS2 are seriously needed• A Common approach on risk assessment

for Dithiocarbamates expressed as CS2 is also needed

Complicated Residue Definitions can triggerdifficulties in Risk Assessment studies: the CS2 case


The case of CS2 : from Official Controls at the · Complex Residue Definitions can trigger...

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