Urine tests in Bomet, Kenya links firewood to increasing throat cancers

The use of firewood in indoor cooking has been linked to increasing cases of cancers of the food pipe in rural western Kenya.

Urine samples collected from adult volunteers in Bomet County showed high levels of harmful chemicals associated with firewood smoke.

Further tests showed volunteers with high concentrations of the chemicals called polycyclic aromatic hydrocarbons or PAHs were at high risk of developing esophageal cancer.

When wood is burned it produces PAHs which may be inhaled by people exposed to the resultant smoke.

Exposure to large amounts of PAHS, scientists say may cause health problems including suspected cancers.

Many Kenyans in rural areas use firewood for cooking and mainly in closed indoor spaces exposing themselves and their families to harmful smoke.

Once inhaled the chemicals convert into substances that are passed out of the body in the urine and feaces.

“We wanted to find out the levels of PAHs in rural populations and whether this may be a risk factor for esophageal cancer,” says the study in the journal Environment International.

The study was carried by researchers from Tenwek Hospital, Bomet, Kenya, the US Centers for Disease Control and Prevention, Brown University, US, Mayo Clinic, US, and the US National Cancer Institute.

The study had recruited 305 adult males and females with no cancer symptoms and residing within 50 km of the 361-bed Tenwek Hospital in Bomet County.

The participants’ history of cancer risk factors such as age, education, use of alcohol, tobacco, and ‘mursik’ (traditionally fermented milk), and cancer in the family and indoor cooking were recorded.

Participants were then screened for esophageal cancer with urine specimens collected and shipped to the US to be tested for PAHs.

The study reports an association between high levels of the ‘smoke’ chemicals and esophageal cancer.

“We found a suggestive association between PAH exposure biomarkers and advanced esophageal dysplasia, the precursor lesion of cancer of the esophagus,” says the study.

The chemicals concentration in women was twice higher than in men, mainly because women are likely to spend longer times in the smoky kitchens than males.

All but one person in the study used wood for cooking, which the study says is widespread in rural Kenya.

The highest PAH exposure was associated with cooking in an enclosed room on open, unvented stoves, without chimneys or adequate room ventilation; and the use of wood as cooking fuel.

These findings, the team suggests may justify community-based efforts, such as installing efficient cookstoves with chimneys.

Other recommendations include changing to less harmful fuels and increasing ventilation in the cooking areas.

By Gatonye Gathura

The report is available here:  https://doi.org/10.1016/j.envint.2021.106485

About Gatonye Gathura 125 Articles
Science Journalist

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