Exploring cadmium exposure as a contributor to male infertility: insights from the relationship between environmental pollutants and the male reproductive system

Abstract

This paper is a narrative review focusing on the association between environmental cadmium exposure and male reproductive dysfunction. The relationship between environmental pollutants encountered in daily life and the male reproductive system is attracting increasing attention. Humans are exposed to cadmium through inhalation, dietary intake (food) and other routes, leading to adverse health effects. This study systematically searched PubMed, Web of Science, and CNKI databases from January 1, 2020, to December 31, 2024, and included 40 eligible in vivo studies based on standardized selection criteria. This study reviewed and analyzed relevant animal experiments conducted in recent years. Based on the lowest observable adverse effect level (LOAEL, 10 μg/kg/d) for reproductive toxicity in rats from a chronic 90−day study (Ait Benbella et al., 2025), the minimum critical human equivalent dose (HED) of cadmium−induced male reproductive damage was calculated, All 40 studies in Table 1 were selected according to predefined inclusion/exclusion criteria (see Section 2). The Lowest-Observed-Adverse-Effect Level (LOAEL) was converted to HED using the following formula: HED(mg/kg)=Animal LOAEL (mg/kg)×km of animal km of human (The LOAEL was derived from rat reproductive toxicity data (10 μg/kg/d) (Ait Benbella et al., 2025); km factors of 6 (rat) and 37 (human, 60kg) were applied. The calculated HED was 0.002 mg/kg/d.) Comparisons reveal that cadmium exposure levels in some regions approach or even exceed this threshold. The results suggest that cadmium may cause damage to the male reproductive system, potentially adversely affecting semen quality. Cadmium also induces renal dysfunction that indirectly exacerbates testicular injury via the renal−testis axis, further disrupting the hypothalamic−pituitary−testicular axis and amplifying reproductive toxicity. These findings highlight the integrated renal−reproductive toxicity of environmental cadmium exposure.