Abstract
Naphthalene and benzene are widely-used volatile organic compounds. The aim of this research was to examine the toxicological effects of naphthalene and benzene against Tribolium castaneum as an animal model. Adult insects were exposed to these aromatic compounds to assess mortality after 4–48 h of exposure. The lethal concentration 50 (LC50) for naphthalene, naphthalin, and benzene were 63.6 µL/L, 20.0 µL/L, and 115.9 µL/L in air, respectively. Real-time polymerase chain reaction (PCR) analysis revealed expression changes in genes related to oxidative stress and metabolism [Glutathione S-Transferase (Gst), and Cytochrome P450 6BQ8 (Cyp6bq8)]; reproduction and metamorphosis [Hormone receptor in 39-like protein (Hr39), Ecdysone receptor: (Ecr), and Chitin synthase 2 (Chs2)]; and neurotransmission [Histamine-gated chloride channel 2 (Hiscl2)] in insects exposed for 4 h to 70.2 µL/L naphthalene. Adults exposed to benzene (80 µL/L; 4 h) overexpressed genes related to neurotransmission [GABA-gated anion channel (Rdl), Hiscl2, and GABA-gated ion channel (Grd)]; reproduction and metamorphosis [Ultraspiracle nuclear receptor (USP), Ecr; and Hr39]; and development (Chs2). The data presented here provides evidence that naphthalene and benzene inhalation are able to induce alterations on reproduction, development, metamorphosis, oxidative stress, metabolism, neurotransmission, and death of the insect.
Highlights
Of all the volatile organic compounds, benzene and naphthalene are amongst the most widely-used in diverse chemical, industrial, and commercial processes, as well as in combustion and evaporation of gasoline, and they are constituents of several commercial products such as cleaning fluids, paints, and glues
The Median Lethal Concentration (LC50 ) of naphthalene, naphthalin, and benzene were determined in T. castaneum adults exposed for 4, 8, 24 and 48 h (Figure 1 and Table 1)
The results showed that naphthalin is highly toxic to T. castaneum
Summary
Of all the volatile organic compounds, benzene and naphthalene are amongst the most widely-used in diverse chemical, industrial, and commercial processes, as well as in combustion and evaporation of gasoline, and they are constituents of several commercial products such as cleaning fluids, paints, and glues. Naphthalene is a bicyclic aromatic compound used as the starting material for the synthesis of other compounds, as a moth repellent (naphthalin), soil fumigant, and lavatory deodorant [1]. Because of their low cost, naphthalin (Nap balls) are often used illegally for sale in the market, they are known to be harmful to humans [2]. Most exposure occurs through low dose chronic inhalation, dermal contact, or ingestion through the food chain [1]. These compounds are ‘high production volume’ chemicals (they are consumed in excess of one million pounds per year) used as industrial plasticizers, and they are ubiquitous environmental pollutants.
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