A method for inhibiting methane production in naturally occurring or induced reducing conditions, thus subsequently resulting into inhibition of the biomethylation process of the heavy metals is disclosed. The disclosed inhibiting composition blocks 3-hydroxy-3-ethylglutaryl coenzyme A (HMG-CoA) reductase, and 8-hydroxy-5-deazaflavin (coenzyme F420) in the methane production pathway, due to the presence of lovastatin in the red yeast rice. As a result the methanogens are unable to produce enough quantities of methane that will result to the production of methylmetal(loids), which are usually volatile and more toxic than their inorganic counterparts due to increased water solubility and hydrophobicity.