Welcome back to Mobs36!

The problem in pollution is only represented in Minecraft by things like dead coral blocks. Let's add some mobs (more than just this one) themed with trash!

Toxitrash is a trash creature. Its main body acts like a slime, and it has two ears that hold most of the trash it consumes. Toxitrash constantly poisons the player. It can drops slimeballs, rotten flesh, its ears, and rarely gold ingots, or nautilus shells.

Above: Toxitrash's loot.

Above: Toxitrash's ears.

To summon Toxitrash:
/summon slime ~ ~1 ~ {CustomName:"\"Toxitrash\"",CustomNameVisible:1,PersistenceRequired:1b,CanPickUpLoot:1b,Size:1,Health:8,Attributes:[{Name:"generic.maxHealth",Base:8},{Name:"generic.movementSpeed",Base:0.1f}],Silent:1,Passengers:[{id:"drowned",CustomName:"\"Toxitrash\"",CustomNameVisible:1,PersistenceRequired:0b,CanPickUpLoot:1b,Health:2,Attributes:[{Name:"generic.maxHealth",Base:2},{Name:"generic.followRange",Base:0},{Name:"generic.movementSpeed",Base:0f},{Name:"generic.attackDamage",Base:0}],Silent:1,Age:-6000,ArmorItems:[{tag:{display:{Name:"Toxitrash Ears",color:7518311},Enchantments:[{id:depth_strider,lvl:3}]},Count:1,id:"minecraft:leather_boots"},{},{},{}],ArmorDropChances:[2F,0F,0F,0F],ActiveEffects:[{Id:14,Amplifier:0,Duration:2147483647}]}]}

To make it venomous and gross:
Do the repeater circle as shown with ESPER. This time, the commands should be:
/execute as @e[type=slime,name=Toxitrash] run effect give @p poison 10
/execute as @e[type=slime,name=Toxitrash] run replaceitem entity @p armor.head slime_block 1
/execute as @e[type=slime,name=Toxitrash] run playsound entity.drowned.swim hostile @p