**6. Epigenetic effect of arsenic on reproductive system**

Epigenetics is the study of how cells control gene activity without altering the DNA sequence. It was reported that arsenic causes hypermethylation of the of the p53 gene and thus, gained the attention of the researchers regarding the epigenetic effects of arsenic [43]. Exposure to inorganic arsenic is found to be associated with epigenetic modifications like gene specific DNA methylation, histone acetylation, phosphorylation, methylation and altered expression of miRNAs, which may induce carcinogenesis or other diseases [44]. According to a report, arsenic exposure during gestation increases the hypomethylation of active Long Interspersed Nuclear Element (LINE) and Long Terminal Repeat (LTR) subfamilies of the offspring sperm, causing transgenerational effects. The study indicates that retrotransposon methylomes in the sperm is one of the main targets of arsenic when exposed during gestation period [45]. Another study showed that arsenic (As2O3) exposure to parents at a dose of 1 mg/L has adverse transgenerational effects on the reproductive phenotype in both male and female offspring after attaining maturity, which may be due to an altered global DNA methylation pattern in gonadal tissue [46]. Thus the studies indicate that arsenic exposure at the gestation period is enough to induce toxicity in the reproductive system of the future generations.
