First surveillance of SARS-CoV-2 and organic tracers in community wastewater during post lockdown in Chennai, South India: Methods, occurrence and concurrence.

Surveillance of SARS-CoV-2 and organic tracers (OTs) were conducted in the community wastewater of Chennai city and the suburbs, South India, during partial and post lockdown phases (August-September 2020) as a response to the coronavirus disease 2019 (COVID-19) pandemic. Wastewater samples were collected from four sewage treatment plants (STPs), five sewage pumping stations (SPSs) and at different time intervals from a suburban hospital wastewater (HWW). Four different methods of wastewater concentrations viz., composite (COM), supernatant (SUP), sediment (SED), and syringe filtration (SYR) were subjected to quantitative real time-polymerase chain reaction (qRT-PCR). Unlike HWW, STP inlet, sludge and SPS samples were found with higher loading of SARS-CoV-2 by SED followed by SUP method. Given the higher levels of dissolved and suspended solids in STPs and SPSs over HWW, we suspect that this enveloped virus might exhibit the tendency of higher partitioning in solid phase. Cycle threshold (Ct) values were < 30 in 50% of the HWW samples indicating higher viral load from the COVID-19 infected patients. In the STP outlets, a strict decline of biochemical oxygen demand, >95% removal of caffeine, and absence of viral copies reflect the efficiency of the treatment plants in Chennai city. Among the detected OTs, a combination of maximum dynamic range and high concurrence percentage was observed for caffeine and N1 gene of SARS-CoV-2. Hence, we suggest that caffeine can be used as an indicator for the removal of SARS-CoV-2 by STPs. Our predicted estimated number of cases are in line with the available clinical data from the catchments. Densely distributed population of the Koyambedu catchment could be partly responsible for the high proportion of estimated infected individuals during the study period.

Chlorpyrifos: lack of cognitive effects in adult Long-Evans rats.

Female Long-Evans rats were gavaged 5 days a week for 4 weeks with chlorpyrifos in oil at dosages of 0, 1, 3, and 10 mg/kg/day. Clinical observations were conducted, and memory was tested with a delayed matching-to-position task (DMTP). Before exposure started, the rats were divided into four groups of ten of comparable overall performance. Then, they were tested during four weeks of dosing and for another four weeks thereafter. The observer was not provided information about each rat's dose group identification. Miosis was a prominent sign observed in the 3 and 10 mg/kg/day groups. Rectal temperature was reduced in the 10 mg/kg/day group. Noncognitive performance measures in the DMTP test (e.g., actual total delay, void trials) were affected and consistent with decreased motor activity. There was a statistically significant difference in the intercept at the zero delay (i.e., a measure of encoding/motivation/attention), which was attributed to deviations from controls in the high-dosage group during dosing weeks 2 and 3 (in opposite directions). This difference was not considered treatment related. The slope of the retention gradient (i.e., a measure of forgetting rate) did not show any statistically significant difference between groups at dosages that inhibited brain cholinesterase by up to approximately 85%. In conclusion, chlorpyrifos decreased motor activity but had no effects on short-term memory (i.e., information retention capability) and on encoding/motivation/attention.

Single-dose and 13-week repeated-dose neurotoxicity screening studies of chlorpyrifos insecticide.

Chlorpyrifos (CPF), a widely used organophosphate insecticide, was screened for neurotoxic effects in Fischer 344 rats using United States Environmental Protection Agency 1991 guidelines for single-dose and 13-wk repeated dose studies. The studies emphasized a functional observational battery (which included grip performance and hindlimb splay tests), automated motor activity testing and comprehensive neurohistopathology of perfused tissues. Doses of up to 100 mg/kg body weight in corn oil by gavage in the single-dose study and up to 15 mg/kg body weight/day in diet for 13 wk in the repeated dose study were administered. It is known that CPF and other phosphorothionates can be activated to the oxon in local (extrahepatic) tissues. Local activation could possibly cause different effects in different tissues with cholinergic innervation, and thereby create syndromes unique to each phosphorothionate according to their structure. Consequently, the conduct of CPF neurotoxicity screening studies by contemporary guidelines offered opportunity to characterize the CPF over-exposure syndrome in rats. Single-dose high levels of oral exposure to CPF caused a range of clinical signs characteristic of cholinergic overstimulation. Although there was no clinical evidence of wide differences in sensitivity of one cholinergic response versus another, motor dysfunction (incoordination etc.) was more prominent than other signs, for example soiling. Effects were much more apparent in females and regressed over several days. Effects were minimal in the 13-wk study, and there was no evidence of accumulation of toxicity during the 13 wk of daily dietary exposure. Motor activity was decreased at the high dose in males and females at wk 4, but was not significantly different from controls in subsequent weeks. The 'normalization' of motor activity later in the study was interpreted as tolerance to repeated administration of CPF. Comprehensive neuropathological examination revealed no treatment-related lesions in either study.