CONSUMER SAFETY:MANCOZEB RESIDUES IN TOMATOES

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STUDY BACKGROUNDO The increased use of pesticides on

tomatoes has raised a number human health concerns as a result of risks from shortcomings in protective clothing, large deviations from recommended doses, and failure to observe the recommended pre-harvest interval by minimally educated farmers (Karungi .J. et al., 2011; Williamson .S, 2003).

O For example tomato farmers have been found to apply Mancozeb concentrations 3-7 times the recommended dose of 2.5g/l. (Kaaya .N.A. , 2004).

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…background…O Mancozeb (a dithiocarbamate) is a fungicide

with contact and protectant action. The health concern with it, is its potential occupational health risks to its handlers and potential effects on the general population from dietary exposure to residues left on food crops.

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…background…O Acute symptoms of exposure include; itching,

scratchy throat, sneezing, coughing, inflammation of the nose or throat.

O Chronic health risks are associated with metabolite carbon disulphide (CS2), a neurotoxin capable of damaging nerve tissue and another metabolite, ethylenethiourea (ETU) which has potential to cause goiter, birth defects, and cancer (Cornell University, 1993).

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..background…O In Uganda, mancozeb is marketed under

trade names of DITHANE M45, EMTHANE, M45 and LANCOZEB among other names. In other cases, it is formulated with another active ingredient, for example metalaxyl and marketed under trade names of TATA MASTER, FANGOCIL, RIDOMIL GOLD and PILARXIL (MAAIF chemical register, 2013).

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Specific objectives of this study

O To assess the mancozeb residue levels in tomatoes from Nangabo small scale farmers

OTo investigate the concentration levels in tomatoes on the local market.

OTo study the effect of simple washing of treated tomatoes on the traces of mancozeb residues in tomatoes. 6

MATERIALS AND METHODS;materials

O Laboratory consumables - Hydrochloric acid (AR), Iso-octane (GC grade), Carbon disulfide reference standard, vials, distilled water, lab wear etc

O Sampling bagsO StickersO Markers/pensO Field wear

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Study Area

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Farmers Area Number of

farmersKabanyolo 1Kiiti A 3Nalusuuga 4Magere 5Kabubu 3Kyakima 1Masooli 2Kitegombwa 1

209

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Vendors Market Number of vendorsKalerwe 5Gayaza 4Kasangati 2Mpererwe 3Magiggye 3Kumukaaga 1Matugga 4Kiteezi 1Luteete 1Busukuma 1

25 11

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RESULTS-farmersO The Codex (FAO & WHO 2013) Maximum

Residue Limit (MRL) in tomato for dithiocarbamates is 2 mg CS2/kg.

O 9/19 (47.4%) of sampled farms had residues above the Codex MRL.

O The highest residue level recorded was 7.7 mg CS2/kg (285% above the codex MRL) which corresponds with the highest dose rate of 15 spoons (150g) of Mancozeb per 20L of water (against the recommended 50g/20L).

O NB: 1 spoon=10g 13

146 spoo

ns

6 spoo

ns

8 spoo

ns

14 sp

oons

7 spoo

ns

4 spoo

ns

15 sp

oons

5 spoo

ns

10 sp

oons

10 sp

oons

10 sp

oons

3 spoo

ns

5 spoo

ns

10 sp

oons

8 spoo

ns

6 spoo

ns

5 spoo

ns

8 spoo

ns

5 spoo

ns0

1

2

3

4

5

6

7

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Mancozeb residues (red bars represent samples above Codex MRL)

Results-vendorsO 16% samples from vendors had

concentration levels above the codex MRL.

O None of the washed samples had a concentration above the MRL.

O Simple washing reduced mancozeb residues by 76.3%.

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Kasan

gati

Kasan

gati

Kumukaag

a

Lute

ete

Gayaz

a

Busuku

ma

Magiggye

Magiggye

Gayaz

a

Gayaz

a

Mperer

we

Mperer

we

Mperer

we

Kalerw

e

Kalerw

e

Kalerw

e

Kalerw

e

Kalerw

e

Matugga

Matugga

Matugga

Matugga

Kiteez

i 0

1

2

3

4

5

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Mancozeb residues (mg CS2 /kg) in tomatoes from vendors

Unwashed tomatoes Washed tomatoes

Observation O Dose rate and PHI (for farmers’ samples) and

in addition, washing (for vendors) are the independent variables that explain variation in mancozeb residues

O Since Mancozeb has no systemic action, washing of tomatoes reduces the mancozeb residues greatly BUT NO COMPLETELY

NB: There is an increased number of formulations where Mancozeb is mixed with other active ingredients.

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Future prospectsO DGAL testing for other chemical residues

(organophosphates, pyrethroids etc) from remaining samples

O Potential tests on organically grown tomatoesO Potential tests on effect of

heating/boiling/cooking tomatoes on chemical residues

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I THANK YOU ALL

prepared by Aggrey(atuagrey3@gmail.com)

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