Daijiworld Media Network - New Delhi
New Delhi, Sep 26: Long-term exposure to benzene may be associated with an increased risk of allergic rhinitis and mortality among older adults, according to a large UK study.
Researchers found that higher exposure to benzene, a chemical commonly present in crude oil, gasoline and cigarette smoke and also found in several industrial and contaminated consumer products, was associated with a greater incidence of allergic rhinitis.
The study also suggested that biological ageing and genetic susceptibility could influence the relationship between benzene exposure and allergic disease.
Allergic rhinitis is an inflammatory condition affecting the nasal passages and commonly causes sneezing, nasal congestion, itching and a runny nose.
Although previous research has linked environmental pollution with respiratory and allergic conditions, the relationship between long-term benzene exposure and allergic rhinitis among older adults has remained unclear.
For the study, researchers analysed data from 76,183 UK Biobank participants aged 65 years or older at baseline. Annual residential exposure estimates for benzene between 2006 and 2020 were used to assess their association with newly diagnosed allergic rhinitis and all-cause mortality.
The researchers also examined four markers of biological ageing and a genetic risk score based on 35 genetic variants associated with allergic rhinitis.
During median follow-up periods of 13.3 years for allergic rhinitis and 14.8 years for mortality, researchers recorded 756 new cases of allergic rhinitis and 17,963 deaths.
Each interquartile-range increase in benzene concentration, equivalent to 0.151 micrograms per cubic metre, was associated with a 44 per cent higher hazard of developing allergic rhinitis.
The same increase in exposure was associated with a 21 per cent higher hazard of all-cause mortality.
Researchers identified exposure levels of approximately 0.255 micrograms per cubic metre for allergic rhinitis and 0.277 micrograms per cubic metre for mortality at which the respective associations changed.
Further analysis indicated that biological ageing could partly explain the association between benzene exposure and allergic rhinitis.
Genetic susceptibility also appeared to affect the risk. Participants in the highest genetic-risk group had a 54 per cent higher hazard of developing allergic rhinitis compared with those in the lowest-risk group.
The findings suggest that chronic exposure to relatively low concentrations of benzene could be relevant to allergic rhinitis risk among older adults. Biological ageing may represent one pathway connecting environmental exposure with allergic disease, while genetic susceptibility could help explain differences in individual vulnerability.
However, the study was observational and therefore cannot establish that benzene directly causes allergic rhinitis or increases mortality risk.
The researchers also noted that residential exposure estimates may not accurately reflect individuals’ actual exposure levels.
Further studies are needed to understand the biological mechanisms involved and determine whether reducing benzene exposure could lower the incidence of allergic rhinitis.
The authors said environmental exposure, biological ageing and genetic susceptibility should be considered together when examining allergic diseases among older populations.