Sperm count and quality have declined drastically over the last decades (FPF reported and here), but it is not yet completely understood which factors are responsible for the deterioration. To help answer this, Andreas Kortenkamp from Brunel University London, UK, and co-authors performed a mixture risk assessment for 29 chemicals to clarify those driving a decline in semen quality.
In an article published on June 17, 2022, in the journal Environment International, Kortenkamp et al. described that they selected 29 chemicals capable to deteriorate semen quality for their analysis. These included androgen receptor antagonists (e.g., certain bisphenols) as well as substances that suppress testosterone synthesis (e.g. certain phthalates), disrupt prostaglandin signaling (paracetamol), activate the aryl hydrocarbon receptor (e.g., polychlorinated dibenzodioxins and -furans (PCDD/F)), or inhibit steroidogenic enzymes (linuron, CAS 330-55-2). For nine chemicals including the bisphenols BPA (CAS 80-05-7), BPF (CAS 620-92-8), and BPS (CAS 80-09-1), the phthalates di(ethylhexyl) phthalate (DEHP, CAS 117-81-7), di-n-butyl phthalate (DnBP, CAS 84-74-2), butylbenzyl phthalate (BBzP, CAS 85-68-7 ), and diisononyl phthalate (DiNP, CAS 68515-48-0 ), as well as for n-butyl paraben (CAS 94-26-8), and paracetamol (CAS 103-90-2), human exposure was calculated based on spot urine samples collected from 98 Danish males between 10 and 30 years of age. For the remaining 20 substances, the scientists collected exposure data from different sources. Using risk quotients of daily intake doses and reference doses for declines in semen quality, Kortenkamp et al. employed the Hazard Index approach (Teuschler and Herztberg, 1995). This approach allows for assessing by how many folds the “acceptable” mixture exposure is exceeded relative to an index value of 1. The study was conducted as part of the European Human Biomonitoring Initiative (HBM4EU) (FPF reported and here).
The results showed “alarming exceedances of acceptable combined exposures.” Considering only the nine chemicals monitored in urine, acceptable exposures were exceeded by 17-fold (median). In highly exposed males, the index value was exceeded even by more than 100-fold. BPA was the chemical that most strongly contributed to the Hazard Index. However, even if exposure sources for that chemical would be eliminated, combined exposures of all other chemicals would still be above acceptable levels, the authors clarified. Polychlorinated dioxins, BPS, BPF, and DEHP, as well as paracetamol in persons using drugs, followed BPA in their levels of contribution. Kortenkamp and co-authors emphasized that their analysis “has the character of a prediction which could be verified in suitably designed epidemiological studies of semen quality. However, regulatory action such as a ban of BPA from food contact materials should not be delayed until such verifications are available, which may take some time.”
Reference
Kortenkamp, A. et al (2022). “Combined exposures to bisphenols, polychlorinated dioxins, paracetamol, and phthalates as drivers of deteriorating semen quality.” Environment International. DOI: 10.1016/j.envint.2022.107322
Read more
Carrington, D. (June 2022). “Cocktail of chemical pollutants linked to falling sperm quality in research.” The Guardian
