INAPPROPRIATELY STORAGED DDT AS A POTENTIAL RISK FOR HUMAN

HEALTH AND ENVIRONMENT

6th ALPS-ADRIA SCIENTIFIC WORKSHOP

30 April - 5 May, 2007 Obervellach, Austria

by Sanja MilošCroatian Food Agency

DDT (dichlorodiphenyltrichloroethane)

and its metabolites:

• very significant for environment and

public health worldwide

• normally regulated trough maximum

residue levels (MRLs) - permitted in food

on sale

• MRLs are not strictly “safety limits”

DDT now banned in most countries:

• was used mainly to control mosquito-borne malaria

• civilian populations to control typhus and malaria vectors

• extensively used as an

agricultural insecticide after 1945

During seventieths of the last century DDT was proscribed mainly because of the environmental effects (persistency, bioaccumulation, negative impact wildlife), but not because of

eventually toxics effect on humans.

Prohibited use of DDT in Croatia:

• during seventieths of the last century by taking

the model from other countries

• Stocholm Convention about Persistent Organic

Pollutants (held in 2001, with appliance from

2004)

• National Plan for Implementation of Stockholm

Convention Principals in December, 2004.

. . . after the ban implementation:

remaining quantities of DDT

• entombed all around the agricultural properties and forestry sectors • several decades later,

during old storehouse disintegration, the unknown quantities of DDT were split around

... possibility of well water pollution becomes quite realistic in these

situations • consumption of water at the area of

Osijek-Baranya County is mostly provided by

exploitation of ground waters

• 20 % of populations drink water from shallow

wells independently of public water supply

availability

In this very case the story started…

suspicious pesticide intoxication of a woman hospitalized in Osijek clinical hospital

epidemiological investigation

identified origin of exposure

uncontrolled effusion of buried DDT stocks during old storehouse disintegration

ALARM

Sampling in a disputable area

Soil sample was

sampled from 30 and

60 cm depth

Water well was sampled

in concentric distance of

200 m

• concentration of DDT was 2 g/kg dry matter (MRL is 0,5 mg/kg)

• 30 (60) m distance had

3.85 (2.31) µg/l• 100 m distancehad (n=3) 0.012 – 0.057 µg/l

The results of measuring concentration

of DDT (µg/l) in water from wells

LocationDistance from

source of pollution (m)

Elapsed Time from pollution (weeks)

0 2 4 10

1. 30 3.85* 1.093* 0.12* 0.0152

2. 60 2.31* 0.025 0.010 0.049

3. 100 0.08 0.057 0.01 -

4. 150 0.026 0.012 0.008 -

5. 200 0.0022 0.038 0.003 -

DDT was detected by gas chromatography (Aglient 6890 ECD) and confirmed by GC MS (Thermo – Finnigen)

• in the well water samples, sampled several days after the incident and heavy rain, the measurements have shown higher concentrations on two locations 30-60 m apart from the origin of pollution

• sampling two and four weeks after the incident was performed in the period without rainfalls and high temperatures, concentration of DDT has been reduced upon the standard referred in the literature

3,85

1,039

0,12 0,0150

1

2

3

4

5

6

0 2 4 10

weeks

co

nc

DD

T/m

icro

g/l

Dynamics of DDT remission in one of the tested wells

Exposure assessment as part of Chemical Risk Assessment performed:

Considering known values it was estimated that the EDI* (estimated daily intake) was 0,005775 mg/l

EDI=average daily consumption of water

×

maximal measured

concentration of DDT in water

It is expected that water for human consumption

should be out for use throw several weeks.

Whats that mean ?

For a grown - up man of 70 kg body weight it was less than ADI* and RfD**, but in the percentage zone of ADI (30%). But under various scenarios such elevated concentration and water consumption (increased consumption lead to breakthrough of ADI)

The consequence may be far reaching

*ADI – acceptable daily intake, 0.02 mg/kg/day for DDT

**RfD – reference dose, 0.0005 mg/kg/day

Contexts of food

safety Stocks of expired and banned pesticides are still

“hot” issues in high number, especially developing countries

Risk assessments may play a significant role in the evaluation of risks posed by pesticides

if concentration exceedes above MRL

estimation of (EDI) indicates that there is

possible acute health risk

These findings indicate the necessity of environmental monitoring on the sites of known or suspected chemical storage, whether obsolete or currently in usage

Thank You for attention !