Bioremediation of Agricultural Soils Polluted with Pesticides: a review

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Table 7.
Criteria for classification of pesticides.
Class
Characteristics
LD
50
for the Rat
(mg
·
kg
−
1
Body Weight)
Oral
Dermal
Ia
Extremely hazardous
<5
<50
Ib
Highly hazardous
5–50
50–200
II
Moderately hazardous
50–2000
200–2000
III
Slightly hazardous
>2000
>2000
U
Unlikely to present acute hazard
>5000
>5000
3.2.1. Organochlorines
Considering the mode of action, the organochlorines damage the nervous systems,
since they alter the ion channels. The main effects are hyperexcitability of brain, convulsions,
tremor, hyperreflexia, and ataxia.
Organochlorines have high toxicity and fall into the first classes of WHO classification
(Figure
5
).
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II Moderately 
hazardous 
50–2000 
200–2000 
III Slightly 
hazardous 
>2000 
>2000 
U 
Unlikely to present acute hazard 
>5000 
>5000 
3.2.1. Organochlorines 
Considering the mode of action, the organochlorines damage the nervous systems, 
since they alter the ion channels. The main effects are hyperexcitability of brain, convul-
sions, tremor, hyperreflexia, and ataxia. 
Organochlorines have high toxicity and fall into the first classes of WHO classifica-
tion (Figure 5). 
Figure 5. 
LD
50 
(mg
·
kg
−
1
) of organochlorines for the rat. 
It was noted that the major source for human exposure to organochlorines is food, 
particularly fish products [63]. The OCs are accumulated in fish muscle, and then, they 
become bioaccessible to humans during gastrointestinal digestion. 
Significant concentrations of OCs were found on dust particles. This type of exposi-
tion causes cytotoxic effects on human skin, leading to the development of carcinoma [64]. 
3.2.2. Organophosphates 
The organophosphates (OPs) are acetylcholinesterase inhibitors, which lead to hav-
ing high levels of acetylcholine. The consequence is damage to several organs such as pe-
ripheral and central nervous systems, muscles, liver, pancreas, and brain. Most of them 
belong to the first classes (Ia, Ib, and II) of the WHO classification (Figure 6). 
Figure 5.
LD
50
(mg
·
kg
−
1
) of organochlorines for the rat.
It was noted that the major source for human exposure to organochlorines is food,