by Dr. E. Czaplicki, Ms. B. Podgórska, Ms. M. Rogalińska
and Mr. S. Stobiecki

Presented by Dr. E. Czaplicki

Persistent organic pollutants are chemical substances which are extremely persistent, bioacumulating, relatively toxic and presenting risk of adverse effects to surrounding environment and to human health. Some of them are widely used in the control of important noxious organisms causing damage in agricultural crops.

Large amount of pesticides as obsolete chemicals, overterminated or unaccepted from toxicological as well as environmental point of view were deposited in so called "tombs" or depots due to unproper system of purchase, distribution and price policy in the early period of chemization of Polish agriculture. Special attention is paid to the POPs in the tombs. The amount of pesticides stored on this way is estimated as approximately 10.000 tons in about 350 tombs. What is a tomb? (Fig. 1). Typical tomb is made of concrete rings of 1-2 m diameter and 1-3 m height located underground with bottom and tops covered with concrete lids. The whole tomb, according to the recommendations for construction, should be insulated outside and inside with the tar. Capacity: 1-10 m³; weight of stored pesticides and sometimes also empty containers - 1-10 tons. From time to time rectangular shape tombs of higher capacity were constructed.

In 1992, after almost 20 years of tombs existence, studies were undertaken in order to recognize the range of the problem. First of all intensive research were arranged to find out all the data concerning the content of tombs and other places of storage of obsolete pesticides. Detailed data concerning 96 tombs have been collected.

Also computer database consisting of all authorized pesticides since 1961 has been prepared. The following elements of the authorization certificate were taken into consideration:

* trade name of pesticide

* common name of active ingredient and its content

* chemical group, to which belongs active ingredient

* type of formulation

* class of toxicity (according to the old classification obliging up to

1995)

* name and country of manufacturer

* years of authorization.

On the background of above mentioned parameters ranking of the most frequently occurring chemical groups of pesticides deposited in 96 tombs has been arranged (Table 1).

Predominating 10 chemical groups are listed below:

* 29% - chlorinated hydrocarbons

* 17% - inorganic

* 14% - dithiocarbamates

* 12% - phenoxyacids

* 10% - organophosphorous

* 8% - nitroderivatives.

Carbamates present 4%, tar - 3%, quarternary amines - 2% and phthalimides - 1%.

Analysis of chlorinated hydrocarbons, as chemical group existing in the highest amount in the tombs is presented on the Figure 2.

Among the organochlorines as much as 44% consist of DDT, 21% - of toxaphene, 12% - of DMDT (methoxychlor), 9% - of HCH and lindane, 4% - of hexachlorobenzene and 4% - of aldrin/dieldrin. "Other" chlorinated hydrocarbons consisting about 6% of the total amount of active ingredients are composed mainly by tetradifon, kelevan and pentachloronitrobenzene. The content of POPs in the tombs is presented in the Table 2. Upper part of the Table 2 shows the amount of 9 pesticides belonging to the POPs, from among initially listed 12 POPs. Now, it should be noticed, that endrin, chlordane, and mirex have never been authorized and imported to Poland.

Assuming total amount of 10.000 tons of obsolete pesticides in about 350 tombs, and that active ingredients consist of 32% total weight of these pesticides, the amount of chlorinated hydrocarbons in 96 tombs is estimated as 114 tons, and in expected 10.000 tonnes - as 928 tons.

Pesticides already classified as POPs (aldrin, dieldrin, DDT, HCB, heptachlor and toxaphene) consist almost 75% of total amount of chlorinated hydrocarbons in the tombs.

So-called potential POPs - HCH/lindane present in the tombs in considerable amount should be also taken into consideration. Active ingredient kelevan (trade name of the product Despirol) widely used in the control of Colorado potato beetle is one of the most persistent insecticides and could be also seen as another potential POP.

Computerized data concerning the content of 96tombs gives the possibility of estimation with high probability the content of each unknown depot. For total estimated amount of 10.000 tons of pesticides in the tombs 928 tons of chlorinated hydrocarbons are anticipated.

POPs consist of the following amounts:

* DDT - approximately 400 tons

* toxaphene - approximately 190 tons

* aldrin/dieldrin - approximately 40 tons

* hexachlorobenzene - approximately 37 tons

* heptachlor - less than 1 ton

* HCH/lindane as potential POP - approximately 100 tons

* kelevan, another persistent candidate as potential POP - approximately 20 tons.

Tables 3 presents the list of trade names of POPs containing pesticides, years of their authorization and additionally amounts of active ingredients expressed in kilograms. From the Tables 3 and 4 it can also be found in which years POPs have been banned in Poland. For aldrin it was 1975, for dieldrin - 1975, for DDT - 1975, for hexachlorobenzene - 1978, for heptachlor - 1966, for toxaphene - 1988, for HCH/lindane - 1990, for kelevan - 1978.

Within almost 100 tombs, for which more detailed data were available, it was interesting to find out, which ones present the highest risk for surrounding environment, besides of other reasons (leaching), to establish ranking of risk. For this purpose the following criteria, characteristic for each active ingredient present in the tombs, were taken into consideration: solubility in water and solubility in aromatic solvents, persistence in soil and toxicological properties. The details for each element are given below:

A. Solubility in water:

multiplier 1 - for almost not soluble

2 - for slightly soluble

3 - for easily soluble

4 - for very well soluble

B. Solubility in aromatic solvents

multiplier 1 - for almost not soluble

2 - for slightly soluble

3 - for well soluble

4 - for very well soluble

C. Persistence in soil

multiplier 1 - for neutral for the environment

1.3 - for not persistent

2 - for moderately persistent

3 - for persistent

D. Toxicological properties

multiplier 1 - for neutral

3 - for moderately dangerous

9 - for dangerous

27 - for extremely dangerous

The ranking of tombs the most dangerous for the environment is presented in the Table 4. This ranking is correlated with the content of chlorinated hydrocarbons. There is no correlation between the capacity of tomb expressed in tons of product and total content of active ingredients.

In conclusion it can be stated that predominating chemical group of pesticides in depots is the group of chlorinated hydrocarbons. The majority of them are persistent organic pollutants, mainly DDT and toxaphene as well as so called potential POPs. HCH/lindane, aldrin, dieldrin and hexachlorobenzene are also present in the tombs, but in much lower amount. Other POPs (endrin, chlordane, mirex) have never been authorized in Poland.

On the background of collected and computerized data from 96 tombs it is possible with high probability to estimate the content of each unknown tomb. The above mentioned persistent organic pollutants are no longer used in agriculture, no longer authorized, no longer produced nor imported, but they are underground in huge amount in leaching depots presenting real risk for the environment. The data presented determine one of the basic elements for future remediation activity.