Quercetin is a polyphenol present in numerous fruits and vegetables and therefore widely consumed by humans with average daily dietary intakes of 10-20 mg/day. It is also a popular dietary supplement of 250-1000 mg/day. However, despite the widespread consumer interest in quercetin, due to its possible chemopreventive properties, the extensively studied quercetin presents a highly diverse and complex array of biological effects. Consequently, the present paper provides the first assessment of quercetin-induced hormetic concentration/dose responses, their quantitative features and mechanistic foundations, and their biological, biomedical, clinical, and public health implications. The findings indicate that quercetin-induced hormetic dose responses are widespread, being independent of biological model, cell type, and endpoint. These findings have the potential to enlighten future experimental studies with quercetin especially with respect to study design parameters and may also affect the appraisal of possible public health benefits and risks associated with highly diverse consumer consumption practices.

An analysis of China\'s domestic publications revealed that China\'s hormesis-related research was enormously underestimated. China\'s documented hormesis-related research spans at least four decades, covers a broad spectrum of research areas, and is more abundant than previously thought. These findings should be considered in historical assessments of the concept of hormesis. Moreover, similar to the international literature, different terms have been used to describe the same phenomenon (hormesis), which hampers communication, generalization of findings and accumulation of knowledge. Hence, we advocate that \'hormesis\' should be cited as a keyword in all the relevant publications written in Chinese language.

Evidence of contaminant-induced hormesis is rapidly accumulating, while the underlying mechanisms of hormesis are becoming increasingly understood. Recent developments in this research area, and especially the emergence of the nuclear factor-erythroid factor 2-related factor 2 (Nrf2) as the master mechanism, suggest that contaminants can induce cardiac hormetic responses. This paper collates significant evidence of hormetic response of the heart rate of fish embryos to contaminants, in particular antibiotics, microplastics, and herbicides, characterized by a low-dose increase (tachycardia) and a high-dose decrease (bradycardia). The increase often occurs at doses about 100-800 times smaller than the no-observed-adverse-effect-level (NOAEL). There are also indications for even triphasic responses, which include a sub-hormetic decrease of the heart rate by doses over 106 times smaller than the NOAEL. Such sub-NOAEL effects cannot be captured by linear-no-threshold (LNT) and threshold models, raising concerns about environmental health and highlighting the pressing need to consider hormetic responses in the ecological risk assessment. A visionary way forward is proposed, but addressing this research bottleneck would require improved research designs with enhanced ability and statistical power to study diphasic and triphasic responses of heart rate.

Preharvest ultraviolet C (UV-C) irradiation is an innovative approach for increasing the bioactive phytochemical content of strawberries to increase the disease resistance and nutritional value. This study investigated the changes in individual flavonoids in strawberry developed with three different cumulative doses of preharvest UV-C treatment (low, 9.6 kJ m-2; middle, 15 kJ m-2; and high , 29.4 kJ m-2). Significant accumulation (p < 0.05) of phenolics (25-75% increase), namely, cyanidin 3-glucoside, pelargonidin 3-glucoside/rutinoside, glucoside and glucuronide of quercetin and kaempferol, and ellagic acid, was found in the fruit subjected to low and middle supplemental doses of UV-C radiation. The expression of the flavonoid pathway structural genes, i.e., FaCHS1, FaCHI, FaFHT, FaDFR, FaFLS, and FaFGT, was upregulated in the low- and middle-dose groups, while the early stage genes were not affected by the high dose. FaMYB1 was also relatively enhanced in the low- and middle-dose groups, while FaASR was upregulated in only the low-dose group. Hormetic preharvest UV-C dose ranges for enhancing the polyphenol content of strawberries were established for the first time.

Based on the cooperative virulence index (c.f.) and LC(50) of fipronil, the interaction effect between short-term heat pretreatment and fipronil on 2(nd) instar larvae of diamondback moth (DBM), Plutella xylostella (Linnaeus), was assessed. The results suggested that pretreatment of the tested insects at 30 °C for 2, 4 and 8h could somewhat decrease the toxicity of fipronil at all set concentrations. The LC(50) values of fipronil increased after heat pretreatment and c.f. values in all these treatments were below zero. These results indicated that real mortalities were less than theoretical ones and antagonism was found in the treatments of fipronil at 0.39 and 0.78 mg/L after heat pretreatment at 30 °C at 2, 4 and 8 h. However, pretreatment at 30 °C for 12h could increase the toxicity of fipronil at all set concentrations, the LC(50) of fipronil decreased after heat pretreatment and c.f. values in all these treatments were above zero, which indicated real mortalities were higher than theoretical ones. Pretreatment of the tested insects at 35 °C for 2, 4, 8 and 12h was found to increase the toxicity of fipronil at all set concentrations which resulted in the decrease of LC(50) values of fipronil and c.f. above zero in all treatments with only one exception. Most interactions were assessed as synergism. The results indicated that cooperative virulence index (c.f.) may be adopted in hormetic effect assessment.

Based on the cooperative virulence index (c.f.), the interaction effect between short-term heat pretreatment and avermectin on 2(nd) instar larvae of diamondback moth (DBM), Plutella xylostella (Linnaeus), was assessed. The results suggested that the interaction results between short-term heat pretreatment and avermectin on the tested insects varied with temperature level as well as its duration and avermectin concentration. Interaction between heat pretreatment at 30 degrees C and avermectin mainly resulted in addition. Meanwhile, pretreatment at 35 degrees C for 2 or 4 h could antagonize the toxicity of avermectin at lower concentrations, which indicated a hormetic effect occurred. The results indicate that cooperative virulence index (c.f.) may be adopted in hormetic effect assessment.