Pesticides

POPs pesticides

Amid banned pesticides, organochlorine and mercury-bearing substances, furan derivatives and other chemical compounds belong to POPs. Aldrin, dieldrin, endrin, mirex, chlordane, heptachlor, hexachlorbenzene, DDT, toxaphene make up this group, their brief descriptions are provided below.

 Aldrin (octalen). Belongs to highly toxic substances (extremely hazardous), very dangerous if inhaled or absorbed through the skin. LD50 is within 10.6-67 mg/kg after oral administration to white rats. Very pronounced cumulative properties. The chemical has no irritating properties. Lethal doses for rabbits are within 15/150mg/kg if absorbed through intact skin.

It is used as an intestinal and contact insecticide to control locust and soil pests.

Retains insecticidal activity in storage. If kept in sealed packages retains its properties indefinitely.  

Dieldrin (octalox). The active ingredient is a white crystalline substance with naphthalene odor. Melting temperature is 172-176°C. Volatility at 20°C is 1x10° mg/m. It has been observed that after its application to soil dieldrin has high volatility, in the first 12 hours after application it is 650g/ha. Insoluble in water (0.005mg/100ml at 26°C); very soluble in organic solvents: acetone – 54g/100ml, benzene – 75g/100ml, hexane – 7.7g/100ml at 26°C). Chemically and thermally resistant. Resistant to alkali, weak acids, and to light exposure. No degradation during long-term exposure to heat. Was produced as 1% crop dust, 20% emulsion concentrate, 50% wettable powder.  

It is used as a contact and intestinal insecticide in seed disinfectants. Dieldrin is a potent poisonous substance with high skin toxicity. If kept in sealed containers can retain its properties indefinitely.

Endrin (endrex). A white, crystalline substance, melting temperature is 226-230°. Practically insoluble in water, very soluble in most organic solvents, resistant to alkali and acid environments. Endrin is more toxic than either aldrin or dieldrin, its insecticidal activity is greater. Rat LD50 is 7.5-17 mg/kg. Belongs to 1 class hazard. Was produced as 20% emulsion concentrate, 50% wettable powder, 1-2% dust, 1-5% granules. Used for tick control and as zoocid.  High storage stability.

Mirex. A moderately toxic pesticide (LD50 – 300-600 mg/kg), however one-time ingestion or dermal contact can lead to hyper-accumulation (accumulation factor is less than 1) in warm-blood animals, causing pathological changes in a range of body systems.     

Persistent in the environment. In soils mirex degrades to chlordecone, which has active insecticide properties. 

It is used for ants and crop pests control. In sealed packages retains its properties indefinitely.  

Chlordane. Was produced as 50-70% emulsion concentrates, 5-10% granules, 2-20% kerosene solutions. It is a contact and intestinal insecticide used to control crop chewing pests. Moderately toxic. (Rat LD50 is 457-530 mg/kg). Has high chronic toxicity and may cause poisoning if low-dose exposure occurs regularly. Highly persistent in the environment.   

If chlordane is exposed to water, hydrogen chloride is released, a strong metal corrodent. It should be taken into account during storage. It is allowed to store chlordane only in containers with special corrosion-resistant coatings.    

Heptachlor.Was produced as 22% emulsion concentrate, dust, wettable powder. It is used to protect sugar beet, corn and other crops from a range of soil pests. Highly toxic: mice and rat oral LD50 is 50-500 mg/kg, rabbit dermal is over 2000 mg/kg, 150 mg/m2 concentration is lethal for rats after 4 hours. Has pronounced cumulative properties, skin-resorptive and carcinogenic effects. Oxidized in animals to heptachlor epoxide, which is more toxic than heptachlor.     

In iron air-tight containers can retain its properties indefinitely.  

Hexachlorbenzene.Was produced as 30% light-gray powder. It is used as a crop disinfectant to control causative agents of fungous and bacteriosis diseases.  

A low toxic substance. Rat LD50 is 10000 mg/kg. Has pronounced cumulative properties (accumulation factor is 1). Threshold concentration in cats and rabbits is 9 mg/m3. Causes irritation to the skin and mucous membranes.  

In sealed containers can retain its properties indefinitely.

DDT. A white crystalline substance, melting temperature is 108.5-109°. Low volatility. At 20° vapor pressure is 1,510-7 mmHg. Solubility in water is 0.001 mg/l. Very soluble in many organic solvents: aromatic hydrocarbons and their halogen derivatives, ketones, compound ethers of carboxylic acids.     

Poorly soluble in aliphatic or alicyclic hydrocarbons (up to 4%). The technical product contains 75-76% of the active substance.     

Due to high persistence and pronounced cumulative properties in many countries its agricultural use was banned or sharply restricted, subject to strict regulations.   

In sealed containers can be stored indefinitely.

Toxaphene (polychlorocamphene, chlorophen, octaphen). Practically insoluble in water, very soluble in most organic solvents. At 25° volatility is 4.3, at 38° – 8.6, at 90° – 50.3 mg/l. Degrades if exposed to alkali or ultraviolet.  

It was produced as concentrate, emulsion, dusts. Used as an intestinal and contact insecticide to protect beet-roots, potatoes, peas, cotton and other crops. Highly toxic, accumulated in the environment.  

The key reasons that have led to accumulation of waste pesticides are: ban for use of acquired products due to their high toxicity or environmental hazard; low storage stability, as well as expired chemicals. Over time, due to violations of storage conditions, the package integrity gradually degraded, causing leaks, mixing of chemicals, increased fire and environmental hazards during storage.  

Landfill pesticides cause great concern because of the danger of their release into the environment. There are organochlorines, organophosphates, simazine/triazine pesticides, inorganic and organic acid compounds and derivatives at each landfill. Today, 20 or more years after their disposal, the entire volume of landfill pesticides should be viewed as “mixtures, potentially related to persistent organic pollutants (POPs). There is no doubt that such a large number of POPs and similar chemicals at landfills requires constant monitoring to evaluate their impact on the environment. It seems particularly relevant for those landfills which have no documentation to confirm completion of works aimed at protecting pesticides from atmospheric precipitation or underground waters.

The last two factors determine the nature (intensity) of the dissolution and release of pesticides into underground hydrosphere and further penetration into the human body.

Given the situation, the Ministry of Natural Resources and Environmental Protection of the Republic of Belarus, together with the parties concerned, using foreign aid, has done a lot to ensure safe storage of waste pesticides. Procedures for safe repacking and lengthy storage of waste pesticides have been developed. In Grodno, Minsk and Vitebsk regions, pesticides are almost completely repacked and stored in 160 storehouses under constant surveillance. 1,700 tons of waste pesticides were removed from storehouses in the Brest and Mogilev regions, the Gershony landfill (Brest region) and partly from the Petrikov landfill (Gomel region) and moved to the Communal Unitary Enterprise “Facility for processing and burial of hazardous industrial waste of the Gomel region”.

The work is in progress to eliminate pesticides or arrange their safe keeping at landfills. In addition to the Gershony landfill and ongoing work at the Petrikov landfill, liquidation of the Slonim landfill is underway. Thanks to the grant from the Global Environment Facility, pesticides, removed from the Slonim landfill, are eliminated at specialized foreign enterprises by high-temperature incineration. 

The work has been completed on capsulation of the Verkhnedvinsk landfill (Vitebsk region) with financial support from the GEF Small Grants Program in Belarus.