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