Acute and chronic toxicity of high-grade chlordane (98%) and bioaccumulation were investigated in Daphnia magna at water soluble concentrations obtained without cosolvent. The measured effective concentrations immobilizing 50% of the microcrustacea (95% confidence interval) were 22.6 (19.7-26.1) microg/L at 24 h and 13.4 (11.3-15.8) microg/L at 48 h. This indicated an increase of chlordane toxicity with time of exposure as confirmed in chronic studies. After 21 d of exposure, significant effects on survival were recorded at a chlordane concentration greater than 2.9 microg/L, whereas reproduction (number of offspring per adult, brood size) and length of adults decreased at 0.7 microg/L or more in a concentration- and time-dependent manner. The production of male offspring and developmental abnormalities, consisting of underdeveloped second antennae and shell spines in live neonates, were recorded. The chlordane concentration tested with no significant adverse effect (NOEC) on reproduction of daphnids after 21 d compared with controls was 0.18 microg/L. The bioaccumulation factor of chlordane by daphnids exposed at a level of concentration close to the 21-d NOEC reached 10,600, wet weight, and 244,000, dry weight, after 40 d. The trans-chlordane bioaccumulated to a greater extent than the cis isomer in daphnids, whereas the cis isomer was predominant in the test medium. The results suggest a crucial role of the invertebrates in transfer of chlordane in aquatic food webs and can be used to derive a freshwater guideline for environmental protection accounting for bioaccumulation.

No abstract

Chronic toxicity of chlordane, an organochlorine insecticide, was assessed on Ceriodaphnia dubia under standardized conditions of testing. Results were compared to Daphnia magna to determine the sensitivity of the two freshwater cladoceran species to this persistent organic pollutant (POP) and to explore the possibility of using the 7-day C. dubia test as an alternative to the 21-day D. magna test in chronic toxicity assessment of POPs. The NOEC-7d value of chlordane on reproduction of C. dubia (2.9 μg/L) was much higher than the NOEC-21d value of D. magna (0.18 μg/L), attesting that the 7-day test on C. dubia was less sensitive than the 21-day reproduction test on D. magna to chlordane. However, extending the period of exposure of C. dubia to chlordane from 7 to 14 days led to a NOEC-14d value similar to the NOEC-21d value in D. magna (0.18 μg/L). This study highlights the usefulness of prolonging the exposure time of the reproduction test in C. dubia from 7 to 14 days to increase the performances of the reproduction test on C. dubia for assessing chronic toxicity of POPs.

No abstract

Methomyl (ME) is a carbamate insecticide that is causes a change in biochemical parameters and affects the oxidative state in the body through the production of free radicals. Herbal medicines derived from plant extracts are useful in treating many diseases, as they are considered natural antioxidants that have a protective role against toxins. This study aimed to evaluate the ability of green tea extract (GTE) to treat ME-induced cardiac toxicity in experimental animals. The experimental animals were divided into five groups. Blood and tissue were collected to estimate the biochemical parameters. ME caused significantly elevated levels of AST, LDH, NF-κB, and malondialdehyde. While a significant decrease was observed in levels of superoxide dismutase, a decrease in glutathione and glutathione-S-transferase was observed. Alterations in these biochemical markers were referred to oxidative stress-induced cardiac damage. The administration of GTE at a concentration (1.5%) to the ME treated group caused the tested biochemical parameters to appear close to those of the control group. GTE alleviates ME-induced oxidative stress in female albino mice. A higher concentration of GTE {1.5%} appears to have a better therapeutic effect than a lower concentration of extract {0.75%} in cardiac toxicity ME.