Miguel Motas
Professor of Toxicology in the Department of Social and Health Sciences at the University of Murcia
The study has a large sample size and the analytical technique is correct. The methods are appropriate and the conclusions are supported by a powerful statistical calculation. It is novel because exposure to metals had not been directly related to this hormone, although it is true that it was known from animal studies of the potential of these metals as reproductive toxicants.
The additive effect of the mixture of metals must be taken into account. As this produces the monitored effect, it may be that other metals or even other pollutants of an organic nature act to enhance this effect. The main limitation I consider to be the sample chosen: urine is the route of elimination of metals and each one has a different residence time in the organism and a different percentage of elimination by this route, so that the relationship between metal level and effect would really be better to make it in blood - which represents the amount of circulating metal that can exert a toxic effect - and not in urine, where the metal being eliminated is, by virtue of many toxicokinetic variables unrelated to the possible effect.
Toxicological testing should be routinely implemented in the clinic, as it underlies many chronic and especially reproductive conditions. There is a lack of training in toxicology for clinicians, resulting in under-diagnosis of pathologies associated with toxic compounds in general and metals in particular.