Corruption
Corruption—dishonest and fraudulent conduct by people in power—is among the most important themes in Trash. Mulligan explores the theme through his depiction of a developing-world society where political officials and police collude to maintain a status quo where a large segment of the society is deprived of the basics of survival while others have access to lavish living standards. The chief villain of the novel, Senator Zapanta, the country's vice-president, is a corrupt politician who stole millions of dollars of international aid money through contracts that lined his pockets. When Gabriel Olondriz set out to prove the man's corruption, Zapanta used his power in the justice system to have Olondriz framed for a murder he didn't commit. As Olondriz points out to Gardo and Olivia, there is a ripple effect from Zapanta's corruption. He didn't just steal money once; he also perpetuated an atmosphere of distrust that means richer countries won't send aid to the country because they assume anything they give will be siphoned off by corrupt officials. In this way, Zapanta's corruption precipitates the sustained suffering of thousands.
Poverty
The protagonists of Trash exist in some of the world's most desperate, impoverished circumstances, living amid heaps of garbage produced by the rest of society. Rather than attend school, the boys work all day sorting through rubbish in the hopes of finding any scrap of value. They live in makeshift shanty homes without electricity or water, they are bitten by rats, they wear rags they find, and their feet are thick with callouses, as they are unable to justify the luxury of shoes when they and the families they support are always on the point of starvation. Born into such extreme poverty, the boys are driven by hopes of finding something so valuable that they will be lifted out of their reality. But, as Raphael states at the beginning of the book, most of the time all anyone finds is human excrement wrapped in paper. Ultimately, the novel shows how the pressure of having to survive intense poverty paradoxically brings about a sense of wily cleverness that enables the boys to outsmart the police.
Solidarity
Solidarity—mutual support within a group—is another of the book's central themes. Having been maligned by the rest of society, the people of Behala dumpsite band together as a street family. Mulligan conveys this sense of unity at the beginning of the book when Raphael talks about how everyone in the shantytown gathers around the same cooking fire in the evening. Despite their poverty, Raphael's aunt provides food for others, knowing they will reciprocate when they can. This solidarity among the poor keeps Rat, Raphael, and Gardo united as they set out to discover where José Angelico has stashed the senator's stolen money. Through the sharing of knowledge, food, and the little money available to them, the boys persevere. When they finally get the money they've risked their lives to find, the boys honor José and Gabriel's mission to redistribute the senator's stolen wealth among the poor. Before setting off to hide out in Sampalo, the boys give most of the money away by releasing it into the wind above Behala dumpsite. In this way, they give the rest of the community that has supported them the same opportunity to escape poverty.
Systemic Oppression
As the force that perpetuates the extreme poverty in which the dumpsite people live, systemic oppression is another key theme in Trash. Mulligan explores the theme by depicting a developing-world society in which discrimination against the poor is made normal through widely held attitudes, structures, and expectations. Throughout the book, the boys are cognizant that richer members of society inherently judge and distrust them, looking upon them as beggars and thieves. This attitude is so ingrained that the boys never question it or fight against it. Instead, they adapt, wearing cleaner clothes when they are trying to move undetected through the city, or blending in with other nearly invisible street kids when they need to evade the cops. The discovery of José Angelico's money is so important to the boys because it presents a once-in-a-lifetime opportunity to escape the system that has oppressed them throughout their lives. With enough money for boats, the boys move to the island of Sampalo and become fishermen in a paradise free of societal oppression.
Duplicity
Throughout Trash, Mulligan depicts the child protagonists outsmarting authority figures through well-thought-out lies. The theme first arises when the police come to Behala and ask if anyone has found a bag. Rather than hand over his find, Raphael doesn't trust the police and keeps quiet. When his aunt mentions he found something, Raphael is quick to invent a lie to cover for himself. He then outsmarts his aunt, claiming he only found a wallet and not the bag they want. Mulligan builds on the theme when Rat joins the group and exploits Father Juilliard's trust in him to research José Angelico on the computer. Raphael continues to outsmart authority when the police violently interrogate him and he manages not to give up the truth. Gardo also outsmarts authority figures when he tricks Olivia into helping visit Gabriel in prison, acquiring a flashy new outfit in the process. The theme is also a vital component of José Angelico's storyline, as José plots for years to get his revenge against Zapanta. Only when he has gained his employer's trust after eight years does José rob Zapanta's stolen aid money. Father Juilliard comments that Behala dumpsite boys are some of the greatest liars in the world. But although the book's main characters commit several acts of duplicity against people who trust them, their intentions are pure. The boys jump on an opportunity to lift themselves and their community out of poverty, while José sacrifices his life to correct a historical wrong.
Aspiration
Aspiration—the ambition or hope of achieving a goal—is another significant theme in Trash. Mulligan introduces at the beginning of the book when Raphael comments on how all dumpsite sorters are motivated by the same dream of finding something of real value in the garbage heaps. Raphael, like everyone living in extremely impoverished circumstances, aspires to move beyond a subsistence existence. That goal prevents him from giving over the wallet when the police want it, as he understands it must be of some as-yet-unknown value, greater than what the police offer. That goal also sends him and his friends off on their mission to learn the mystery of what happened to José and the money he took. The theme of aspiration also arises when Rat reveals that he came north from Sampalo to earn enough money to buy a fishing boat. To achieve his goal, Rat deprives himself of nourishment and lives alone, ensuring no one is dependent on him. He puts up with horrible living conditions and days spent sorting through garbage because in his circumstance he can steadily build a savings pile. By the end of the book, Rat attains his goal of fishing in Sampalo, bringing Raphael, Gardo, and Pia to share in the dream.
Violence
While the poverty perpetuated by systemic oppression is itself an insidious sort of violence in Trash, the boys also live with the very tangible threat of physical violence. The theme enters the narrative when a police officer takes Raphael's chin in his hand and questions him. The officer acts as though he is being friendly, but the hint of physical contact implicitly reminds Raphael of the police's state-sanctioned ability to wield violence. That violence erupts when police arrest Raphael and bring him to the station for interrogation. Although he is a child and his hands are tied, the adult police physically assault him as though it means nothing to them. He refuses to give up the truth about the wallet he found, and the police escalate the violence, hanging him out the window by his feet. As he leaves the interrogation room bloodied and disoriented, Raphael reveals to the reader that José Angelico was killed during police questioning in the same station. As someone accustomed to life on the streets, Gardo carries a sharpened hook with him at all times—a necessary tool all dumpsite boys use to fend off attacks. Gardo showcases his own ability to use violence when Marco betrays him and tries to get him arrested. Gardo slashes the man's face with his hook, managing to escape in the process. In this way, Mulligan shows how the threat of attack brings about defensive violence.
