Page 28 - Volume 4, Issue 2, July 2011

1 Laboratory of Toxicological Control of Pesticides, De-

partment of Pesticides Control and Phytopharmacy,

Benaki Phytopathological Institute, 8 St. Delta Str.,

GR-145 61 Kifissia, (Athens), Greece

Corresponding author:

k.machera@bpi.gr

Introduction

The dithiocarbamate class (DTCs) of fungi-

cides comprises a group of plant protection

products (PPP) which are widely used world-

wide. They are the main group of fungicides

used to control approximately 400 patho-

gens of more than 70 crops and are regis-

tered in all the EU member states and many

other countries (18). They are of relatively

low acute toxicity for humans with an aver-

age LD50 of more than 2523 mg/kg bw (41).

Thiram (tetramethylthiuram disulfide) is one

of the most characteristic dithiocarbamates.

It was synthesized in 1931 and since then has

been extensively used as a fungicide (41), as

a seed treatment in maize, cotton and cere-

als (25, 35), as an accelerator and vulcanis-

ing agent during rubber processes as well as

for treatment of human scabies and in anti-

septic soaps and preparations (21, 22). It is

Hellenic Plant Protection Journal

4:

57-69, 2011

Bioaccumulation of thiram in

Mytilus galloprovincialis

and its

effect on different tissues

Ch. Emmanouil

1

, K.M. Kasiotis

1

and K. Machera

1

Summary

The accumulation of thiram, a characteristic dithiocarbamate fungicide, in

Mytilus gallopro-

vincialis

soft tissues and its effect on bivalvian DNA integrity has been examined through a series of

in

vivo

exposures of mussels to 0.1, 1.0 and 10.0 mg thiram/L in saltwater for 48 h. Regarding bioaccumu-

lation of the fungicide, a dose-dependent increase of the sodium adduct ion of thiram was observed

in mussel soft tissues after the end of the exposures. This identification/quantification of thiram and

one of its metabolites was achieved by Liquid Chromatography Mass Spectrometry (LC-MS) analysis.

Regarding DNA integrity (DNA Single Strand Breaks) these were strongly dose-dependent. They were

also tissue-dependent in concordance with the different susceptibility of certain tissues to pollutants

and the levels of metabolism that takes place in them. Further investigation in oxidative and apoptotic

DNA damage revealed that a) oxidative stress was evident in all the tissues examined b) apoptotic cell

morphology was detected in gill and digestive gland. Imbalance of the antioxidant/prooxidant status

in favour of the latter and initiation of apoptosis may be a causative mechanism of DNA damage in

M.

galloprovincialis

, as it has already been shown for DNA damage caused by thiram in mammals.

Additional Keywords:

apoptosis, dithiocarbamates, LC-MS, mussel, oxidative stress, Single Strand Breaks

also an intermediate metabolite of two oth-

er dithiocarbamates-ferbam and ziram (41).

Several analytical methods are available for

the detection and quantification of thiram

and its metabolites. Gas chromatographic

techniques have been applied with determi-

nation of carbon disulfide (CS

2

), the product

of the rapid degradation of DTCs. However,

these methods are laborious and this has di-

rected scientists to the exploitation of LC-

MS methods which offer the advantage of

the direct determination of DTCs and thiram

in particular.

Thiram, like the majority of dithiocar-

bamates, exerts its toxic action via creation

of metabolites of carbon disulfide (43) and it

is of low mammalian toxicity (17). However,

in certain animal models it has caused he-

patotoxicity (24, 25) and adverse develop-

mental and reproductive effects (24, 27, 40).

It has also caused eczema, contact dermati-

tis and skin lesions to exposed workers (21,

22, 40).

Since thiram is so extensively used, it is

commonly found in aquatic environments

(31). According to U.S. Environmental Pro-