Pollution
Pollution was the insertion, toxic or otherwise, of non-native materials into an ecosystem. Components of pollution were called pollutants.

Spock was able to confirm the arrival of the  in the late 20th century due to the high pollution content of the atmosphere. ()

In 2057, Humanity nearly choked to death on air pollution, and within a generation, solar panels were used on everything from trucks to toasters. ()

The Tagrans of Tagra IV requested assistance from the United Federation of Planets to help repair the ecological damage to their homeworld caused by pollution. ()

The technologically-advanced race of Ledos was found to be polluting the area of a more primitive species that was their genetic ancestors, the Ventu. ()

The Malons built an entire industry devoted to the disposal of industrial byproducts such as antimatter waste. This hazardous waste was dumped into open space. ()

The habitability of Mixtus II depended on pollution from the neighboring planet Mixtus III being blocked by the latter's fifth moon. When that moon was demolished in 2380 due to its decaying orbit, it was expected that the inhabitants of Mixtus II – which consisted of a single wealthy couple – would have to evacuate. ()

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Materials
Radiation