Pesticide

**1. Classification of Pesticides:**
– Pesticides are categorized based on target organisms, including herbicides, insecticides, fungicides, rodenticides, and pediculicides.
– Biopesticides encompass microbial pesticides, biochemical pesticides, and plant-incorporated protectants.
– Pesticides can be classified by their mode of action for resistance management.
– Structural classes associated with a single mode of action are used to classify pesticides.
– Pesticides can be categorized as systemic or non-systemic, with systemic pesticides being more effective.

**2. History and Development of Pesticides:**
– Inorganic compounds and plant extracts were initially used as pesticides until the 1950s.
– Synthetic organic compounds like DDT and 2,4-D were introduced in the 1940s.
– DDT accumulation in the food chain led to its global ban in the 1970s.
– Resistance to pesticides was first observed in the 1920s.
– Integrated pest management (IPM) was introduced in the 1950s to reduce pesticide application.
– Developing new pesticides involves testing compounds against target organisms and optimizing active compounds for use as pesticides.
– The cost of developing a pesticide in 2022 was estimated to be 350 million US dollars.
– Finding new pesticides has become more challenging, with fewer new active ingredients introduced in recent years.

**3. Benefits and Drawbacks of Pesticides:**
– Pesticides protect plants from pests like weeds, fungi, and insects.
– They can deter or kill various pests that harm crops or spread diseases.
– Pesticides have drawbacks such as potential toxicity to humans and other species.
– Systemic pesticides move inside plants, while non-systemic pesticides act on the surface.
– Pesticides must be persistent enough to control pests but degrade fast to avoid environmental accumulation.

**4. Global Trends in Pesticide Use:**
– Herbicides are the most commonly used pesticides globally, accounting for around 50% of all pesticide use.
– Organic agriculture, using non-synthetic pesticides, covers about 1.5% of the world’s agricultural land.
– Application rates of pesticides have decreased over the years, but overall usage has increased.
– Amounts of pesticides used have increased significantly in low-income countries compared to high-income countries.
– Genetically modified crops introduced in the 1980s have led to lower insecticide use.

**5. Health Effects and Occupational Exposure:**
– Pesticides can negatively impact health by mimicking hormones and causing cancer.
– Studies show associations between pesticide exposure and diseases like non-Hodgkin lymphoma.
– Occupational exposure among agricultural workers leads to severe pesticide poisoning annually.
– Pesticides are linked to neurological issues, birth defects, and fetal death.
– Challenges in characterizing pesticide exposure include underreporting and unintentional poisonings.