contaminate
verb [ T ]
ENVIRONMENT uk/kənˈtæmɪneɪt/ usto make something less pure or make it poisonous:
The government recently reported that 10% of farmland has been destroyed by pollution and that heavy metals contaminate 12 million tons of grain a year.
There are fears that exported products could contaminate food supplies abroad.
contamination
noun [ U ]
The report concluded that bacterial contamination at the factory could occur no matter what technology was being used.