The Molecule - Deltamethrin

Chemical Name and Formula

• (S)-á-cyano-3-phenoxybenzyl(1R,3R)-3-(2,2-dibromovinyl)-2,2 dimethylcyclopropanecarboxylate
• C22DecisHeading9Br2NO3

Molecular weight

• 505.2 g.mol-1

Solubility

• Highly soluble in most organic solvents (e.g. dichloroethane, acetone) at room temperature. Practically insoluble in water (0.0002 mg/L @ 25°C). Solubility is not pH dependent.

Stability

In Water

• Biological degradation:
  Half-life = 17 hours (field studies in a water/sediment system).
  Abiotic degradation:
  Hydrolytic degradation is pH dependent (stable at pH5, half life = 2.5 days at pH9)
  

• 24 days in aerobic soil,
• 68 days in anaerobic soil (in laboratories studies).

Acute Toxicity

Rat LD50 oral	87-135 mg/kg body weight (bw) (depending on carrier)
Rat LD50 dermal	>2000 mg/kg bw
Rat LD50 inhalation	0.6 mg/L air (6h whole body exposure, dust particulate aerosol)
Skin irritation	non irritant
Eye irritation	non irritant
Skin sensitization	non sensitizing

Genotoxicity

• No genotoxic potential

Long term carcinogenicity

• No carcinogenic potential

Reproductive toxicity

• No developmental or reproductive toxicity

Deltamethrin residues in /on plants & food commodities

• Deltamethrin is a contact product: its extremely low water solubility (0.0002 mg/L) prevents it from solubilizing in water and being up-taken by plant roots. Moreover, its very low vapor pressure (1.24 x 10-8 Pa) prevents any translaminar effect. Thus, residues are found only on plant surface.
• Deltamethrin shows a strong affinity to fat, due to its octanol/water coefficient (log Pow = 4.6). Residues are retained in lipidic parts of fruits/vegetables, and can easily be eliminated for example by peeling.
• In addition, some processes are very effective to reduce considerably the level of residues. For example cooking and blanching: half life of deltamethrin in boiling water is only 9 minutes.