Low Concentrations of Lorsban in Water Result in Far Reaching Behavioral and Histological Effects in Early Life Stages in Guppy

Chlorpyrifos (O, O-diethyl-O (3,5,6-trichlor-2-pyridyl) phosphorothioate) is a broad-spectrum organophosphate compound. A number of previous work of different countries, institutes, and individuals have confirmed that chlorpyrifos is very highly toxic to freshwater fish and to aquatic invertebrates. The acute toxicity and subacute toxic effects on different concentrations of chlorpyrifos in guppy were investigated in the current study. Twelve guppy juveniles (×6) were exposed to a range of chlorpyrifos concentrations and 96 h. There was one control group. Subacute exposures were predetermined based on 96-h LC50 values. Fish were exposed to three concentrations 0.5, 1, and 2.0μ/gL chlorpyrifos (Lorsban) for 14 consecutive days. Numbers of live and dead juveniles, signs of paralysis, and deformations were monitored every 24 h. The acute toxicity results revealed that even low concentrations of Lorsban were toxic to guppy juveniles, and with toxicity being evident from 7.17 μg/L LC50 for 96 h at 26±1C′. Low concentrations of Lorsban were also responsible for changes in swimming behavior. Malformations were common to all treated groups but increased in the highest exposure group. Gill histology revealed several pathological changes, including loss and shortening of secondary lamellae. Collectively, the present study reveals that low concentrations of chlorpyrifos can be highly detrimental to guppy in the early life stages, with clear evidence of behavioral, morphologic, and histologic effects. The present findings warrant further studies.