Aims: Organophosphates are well-known as an important group of poisons. The aim of the current study is to investigate acetylcholinesterase enzyme (ACHE) level in workers' blood of a poison-producing industry and its relationship with annual poison production and the use of personal protective equipment (PPE). Materials and Methods: This cross-sectional study was conducted during 2012–2015 on 84 workers from different units of a poisons-producing industry and a 20-person control group. The PPE used during the years of study includes Asphalt gloves, rubber gloves, and mask felt. The AChE level was detected based on the modified Ellman method. Results: The maximum AChE level was observed in the control group. In addition, the minimum was found in the workers in 2015. The mean AChE level in the control group was significantly higher than that in the worker (P < 0.05). The mean AChE level in the workers based on the study years was significantly different, but this was not significant between the blood samples taken in the years of 2014 and 2015. Furthermore, it was found that both poisons-producing amount and PPE distribution were enhanced more during the past year of the study, while the poison amount entering to the body decreased. Conclusion: It was deduced that the AChE level in workers' blood was lowered with increasing at the exposure years due to irreversible effects. It is also observed that growth at the PPE application acted as an important parameter to decline exposure to poisons and subsequently various health complications.