New research from the Queensland Alliance for Environmental Health Sciences in Australia is taking a very unusual approach to understanding the people in different communities: analyzing their sewage.

The team reports that varying income levels in different communities are linked to different food and drug consumption habits. While that conclusion itself isn’t exactly surprising, the way the team reached it is. This is the first study of its kind to show that these habits result in noticeable differences in the wastewater of individual groups of people.

Data dump

Preivous studies have shown that our drug consumption shows up in wastewater — but this is the first study to track other lifestyle traits using the same approach.

“Although [wastewater-based epidemiology] has primarily been used for measuring drug consumption, our results demonstrate that it can be used to identify sociodemographic patterns or disparities which associate with consumption of specific chemicals or food components,” writes the team, led by Phil Choi, a Ph.D. student at the Queensland Alliance for Environmental Health Sciences in Australia.

Wastewater from wealthier communities, where people had higher educational achievement, showed higher levels of vitamins, citrus, and fiber, the team reports. Wastewater from poorer communities, where people were overall less educated, showed higher levels of prescription pain relievers and antidepressant medications. Wastewater analysis can thus be used to gain insight into the consumption habits of individual communities, the paper concludes.

The study examined samples from 22 water treatment plants from six Australian states over seven consecutive days in 2016. The results were compared to 40 different socioeconomic factors from Australia’s national census (factors such as rent price and education level). Choi’s team then drew correlations between these factors and compounds found in the urine and feces of residents.

One of the strongest correlations the team identified was between socioeconomic status and prescription drug use. Wastewater treatments plants that serve areas associated with lower overall socioeconomic status had higher levels of several prescription drugs in their wastewater. These drugs are:

• tramadol, an opioid pain reliever;
• desvenlafaxine, an antidepressant;
• mirtazapine, an antidepressant;
• pregabalin, a prescription pain reliever;
• atenolol, a blood pressure drug.

While people of lower socioeconomic status do report higher drug use than others, the team notes that the study shows their method is useful to analyze overall trends in a community.

Wealthier and healthier

Dietary fiber and citrus consumption were also strongly correlated with socioeconomic status — an indication that the wealthier households had an overall better diet. Wastewater from wealthier areas also had higher levels of proline betaine, a component of citrus flesh. Enterodiol and enterolactone, which are components found in the waste of people who eat plants, were also found in higher concentrations than in the wastewater of other areas, the team reports. These results suggest that people in wealthier communities mix more fresh fruit and vegetables in their diet.

Areas with higher overall rent rates — those over $470 a week — wastewater contained significantly higher levels of vitamins B3, E, and B6. The researchers identified these compounds by looking for their metabolites (what’s left after our bodies process a particular substance) in wastewater. Areas with the lowest rent rates — areas where people of lower socioeconomic status live — showed lower levels of these vitamins in their wastewater.

The study aims to showcase the role that wastewater-based epidemiology can play in efforts to monitor public health and illicit drug use. There is an ongoing debate on the merits of this field of research, the team notes, revolving particularly around the issue of privacy (the method can be used to gather data on people without their consent). For the moment, however, the findings confirm previous results on the relationship between socioeconomic status and health — richer people eat better and have fewer health issues, the team explains.

The paper “Social, demographic, and economic correlates of food and chemical consumption measured by wastewater-based epidemiology” has been published in the journal PNAS.