Cadmium　(Cd)　is　one　of　the　most　prevalent　toxic　metal　pollutants,　which　is　widely　distributed　in　various　environmental　media　and　organisms.　Literature　studies　have　documented　that　Cd　could　stimulate　cellular　oxidative　stress,　and　the　increased　intracellular　reactive　oxygen　species　(ROS)　might　destroy　certain　proteins　and　DNA　and　subsequently　lead　to　cell　apoptosis.　Although　several　studies　have　studied　the　co-exposure　between　cadmium　and　other　metals,　information　on　the　potential　effects　of　Cd　and　its　counterions　is　still　lacking.　In　the　present　study,　we　explored　the　effects　of　nitrate　and　chloride　on　oxidative　stress　induced　by　Cd(ii)　at　environmental　exposure　levels　in　human　breast　cancer　cells　(MCF-7)　using　scanning　electrochemical　microscopy　(SECM).　After　incubation　in　CdCl2　or　Cd(NO3)(2),　ROS　production　is　concentration-dependent　and　time-dependent,　and　the　variation　trend　is　consistent.　When　MCF-7　cells　were　incubated　at　a　constant　Cd2+　concentration,　it　was　found　that　the　higher　the　concentration　ratio　of　Cd(NO3)(2)/CdCl2,　the　less　ROS　was　generated.　Combined　with　cell-viability,　intracellular　acidification　as　well　as　antioxidants　system　tests,　we　observed　that　nitrate　could　be　reduced　to　nitrite　and　then　inhibit　Cd-induced　oxidative　stress.　Benefitting　from　real-time　in　situ　imaging　of　cells　by　SECM,　H2O2　was　detected　and　quantified　in　a　noninvasive　way,　and　the　effect　of　Cd　at　environmental　exposure　levels　on　cellular　oxidative　stress　was　explored　deeper　and　more　comprehensively.　Prospectively,　cytotoxicological　methods　based　on　the　SECM　technique　would　be　established　to　explore　toxic　pollutant　co-exposure　issues　at　environmental　exposure　levels.