September 12, 2023

expert reaction to study looking at blood levels of organochlorine contaminants mixtures and cardiovascular disease

A study published in JAMA Network Open looks at blood levels of organochlorine contaminants mixtures and cardiovascular disease.

Prof Andy Smith, MRC Toxicology Unit, Cambridge, said:

“The association of very low levels of chlorinated cyclic chemicals in human blood and tissues with various diseases has been investigated for decades; often as here, with groups of mechanistically unrelated compounds.

“In this prospective nested-control study, two of the 25 chemicals estimated, beta-hexachlorocyclohexane and transnonachlor were associated particularly with increased risk of cardiovascular events.  The paper describes these as pesticides but they were in fact contaminants persisting in the body of the disused active ingredient insecticides lindane and chlordane respectively.

“The results are complex to appreciate and many attempts have been made to take in to account confounders such as diet, smoking etc.  A noted aspect of the study is that results are expressed per volume of blood rather than blood fat as in most investigations.  What the results tell us mechanistically is unclear to me and I doubt that experimental findings quoted are helpful in understanding as they involve exposures in animals and cells at much higher levels.

“As all of these chemicals were withdrawn or banned many years before these first Swedish samples were taken, it is difficult to see how this could lead to useful health advice further to what is already agreed for UK exposure and monitoring.

“The last sentence of the paper (Conclusions) probably sums up how it should be regarded: ‘While measures may be needed to reduce this exposure, it is imperative to replicate these findings in diverse settings, particularly through larger prospective cohort studies, to establish their robustness and generalizability’.”

‘Blood Levels of Organochlorine Contaminants Mixtures and Cardiovascular Disease’ by Carolina Donat-Vargas et al. was published in JAMA Network Open at 16:00 UK time on Tuesday 12 September 2023.

DOI: 10.1001/jamanetworkopen.2023.33347

Declared interests

Prof Andy Smith: “No conflicts of interest.”