Current Research on the Safety of Pyrethroids Used as Insecticides

Abstract

Pyrethroids are synthetic derivatives of natural pyrethrins extracted from Chrysanthemum cinerariaefolium. They are 2250 times more toxic to insects than to vertebrates due to insects’ smaller size, lower body temperature and more sensitive sodium channels. In particular, three pyrethroid compounds, namely deltamethrin, permethrin, and alpha-cypermethrin, are commonly used as insecticides and are recommended for in-home insect control because they are considered to be relatively non-toxic to humans in all stages of life. However, recent data show that they are not completely harmless to human health as they may enter the body through skin contact, by inhalation and food or water, and absorption level depending on the type of food. Permethrin seems to have an adverse effect on fertility, the immune system, cardiovascular and hepatic metabolism as well as enzymatic activity. Deltamethrin induces inflammation, nephro- and hepatotoxicity and influences the activity of antioxidant enzymes in tissues. Alpha-cypermethrin may impair immunity and act to increase glucose and lipid levels in blood. The aim of the review is to provide comprehensive information on potential hazards associated to human exposure to deltamethrin, permethrin and alpha-cypermethrin. The results of presented studies prove that the insecticides must be used with great caution.

Biogenic Synthesis of Silver Nanoparticles Using Guava (<i>Psidium guajava</i>) Leaf Extract and Its Larvicidal Action against <i>Anopheles gambiae</i>

“…Synthetic insecticides are widely used to control insect spread as indoor insecticides and residual spraying in treated nets [9]. Their abuse leads to both human and environmental toxicity, thereby potentially eliminating non-target organisms [10].…”

Relationship between Organophosphate and Pyrethroid Insecticides in Blood and Their Metabolites in Urine: A Pilot Study

“…Following the principles of physiologically based pharmacokinetics, insecticides in blood are eventually transformed to hydrophilic metabolites for urinary excretion. A bi-exponential pattern of elimination, a rapid phase followed by a slow phase, fits the metabolisms with half-lives being several hours to a few days [23][24][25][26][27][28][29][30][31][32]. Constant intake and elimination of insecticides (e.g., OPs, PYRs) would reach a steady-state equilibrium in the body [48], in which the levels of insecticides in the blood or that of metabolites in urine remain stable.…”

“…PYRs are commonly metabolized in the body via ester cleavage of the original compounds to trans-chrysanthemumdicarboxylic acid (trans-CDCA), cisand trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid (cis-/trans-DCCA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylic acid (cis-DBCA), 3-phenoxybenzoic acid (3-PBA), and 4-fluoro-3-phenoxybenzoic acid (F-PBA) [22]. The commonly used OPs and PYRs are confirmed to be metabolized in the human body quickly with half-lives of hours to a few days, evidenced by a number of animal and human studies [23][24][25][26][27][28][29][30][31][32]; therefore, these metabolites are usually excreted in urine within days, reflecting the exposure of the latest few days. Determination of the concentrations of these insecticides in blood or their respective metabolites in urine is an effective method to assess human exposure to insecticides [19].…”

Novel acaricides by nanotechnology against cattle ticks and their effect on physiological and productive performance

“…Due to decrease in molecules size and enlarged surface area of nanoparticles empowers easier penetration of the nanoacaricides into tick and enhances its tickicidal activity (Schrof et al, 2003 andHazra et al, 2017). Moreover, the synthetic pyrethroids like cyhalothrin, cypermethrin, permethrin and deltamethrin have proven to be more effective against ticks and it is a safe group on animals and humans (Msolla et al, 2001;George et al, 2004 ;Anadon et al, 2013 andChrustek et al, 2018). Permethrin was the faster acaricide that reached to 100 % reduction of ticks within 3 days.…”