BackgroundChronic mercury intoxication is a severe health issue and occurs especially in gold mining communities. Common chelators used for improving mercury elimination are not everywhere available and challenged by poor cell wall penetration. This study is part of a feasibility trial and the aim was to gather first information about the efficacy of the newly developed chelator N,N‘bis-(2-mercaptoethyl) isophthalamide (NBMI) on chronic mercury intoxication.MethodsIn this three-armed, placebo-controlled randomized trial, 36 miners with mercury urine levels exceeding 15 μg/l were administered 100 mg NBMI, 300 mg NBMI or placebo for 14 days. Levels of mercury in urine [μg/l and μg/g creatinine] and plasma l were analyzed. Therapeutic effect was assessed using the medical intoxication score (MIS) and its single health outcomes (e.g. excessive salivation, sleeping problems), fatigue scores, a neuromotoric test battery (CATSYS) and a neurological outcome (Finger to nose test).ResultsPhysical fatigue was significantly decreased in the 300 mg NBMI group compared to the control. Mercury concentration in urine following 300 mg NBMI treatment was significantly lowered compared to control, however, this effect was less distinct with adjustment for creatinine.ConclusionNBMI showed an effect on physical fatigue and there were indications to positive effects on other symptoms as well. More comprehensive studies are mandatory to verify the effects of NBMI as a novel tool for treating mercury intoxications.Trial registrationClinicalTrials.gov Identifier: NCT02486289. Date of registration: June 24, 2015.Electronic supplementary materialThe online version of this article (10.1186/s12940-018-0358-1) contains supplementary material, which is available to authorized users.