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expert reaction to a study looking at cryptorchidism in France and the local geographical environment

A study, published in Human Reproduction, looked at cryptorchidism in France and the local geographical environment.


Prof Ieuan Hughes, Emeritus Professor of Paediatrics, University of Cambridge, said:

“This French study is a trail-blazer in research on male reproductive tract disorders by using a nationwide analysis of time and spatial trends in cryptorchidism identified by surgical records. So the diagnosis is firm and numbers huge (90,000). The incidence of operated cryptorchidism increased by 36% in just 13 years. How can that happen so quickly? Using a sophisticated spatial disease-mapping model the authors were able to identify spatial clusters (‘hot-spots’) of cases which were related environmentally to heavy industrial areas of France. Is this a significant contribution to the ongoing debate about whether an increase in conditions like cryptorchidism is related to environmental factors such as so-called endocrine disruptors?

“This was a retrospective study and the authors refer to a previous study we undertook in Cambridge which was prospective as part of an ongoing Cambridge Birth Growth Study. This showed a prevalence of cryptorchidism at birth of 5.9% and a higher figure of 7% at 12 months due to acquired cryptorchidism. The authors wrongly stated an increase had occurred between 2001-2008 (this interval was the recruitment period). A doubling of prevalence had occurred in a generation compared with a previous study in the UK. More recently, we have shown in the Cambridge cohort a positive association between maternal blood BPA levels and cryptorchidism, an illustration of the advantage of such prospective studies.

“The rapid increase in the French study may be confounded by the acquired cryptorchidism effect, differences in surgical practices around the country and changes in socio-economic factors which the authors discuss. But, the accompanying editorial headlined……Location, location, location…..1 goes to town on the various factors which could intertwine to explain the findings. The author is an expert in the field and writes with his accustomed clarity and scientific rigour. Numerous potential causes are suggested with cryptorchidism perhaps being a surrogate marker of aspects of general health affected by environmental exposure and poverty. The French study is a clarion call to other countries to replicate their work. Where better for that to occur than in the UK with its vast metropolitan regions, an industrial heritage, contrasting agricultural regions, rank child poverty and ‘levelling up’ on the political agenda. This would keep epidemiologists busy long after the current pandemic has subsided.”

  1. “Location, location, location—where you are born may determine your reproductive (and more general) health” by Richard M. Sharpe is an invited commentary and will be published in Human Reproduction alongside the study at 00:05 UK time on Wednesday 17th March. DOI:10.1093/humrep/deab051


Prof Rod Mitchell, Professor of Developmental Endocrinology, MRC Centre for Reproductive Health, University of Edinburgh, and Consultant Paediatric Endocrinologist, Royal Hospital for Sick Children, Edinburgh, said:

“It is well known that the incidence of male reproductive disorders has been increasing in recent decades and this is likely to be due to environmental factors. However, what these factors might be are largely unknown.

“Failure of the testicles to descend into the scrotum around birth is known as cryptorchidism and is one of the most common disorders in males, occurring in around 3-5% of healthy newborns.

“This very well conducted study investigated nearly 90000 cases of cryptorchidism across the entire country of France between 2002 and 2014. The study found a 36% increase in cases of cryptorchidism requiring an operation over this 12-year period.

“Whilst the increasing incidence of cryptorchidism over recent decades is well described, the rate of increase (36%) demonstrated in this study is of particular concern. Understanding the cause(s) of the increase in cryptorchidism is of high importance for maintaining reproductive health in males.

“The main strength of the study is its large scale and inclusion of data for the entire country. The identification of 24 ‘hotspot’ regions for cryptorchidism, centred around the industrial regions of northern France point to an environmental pollutant or socio-economic cause for these cluster regions.

“The study provides evidence for an association between industrial exposures and cryptorchidism. However, identification of specific environmental pollutants and levels of exposure required to predispose to the development of male reproductive disorders requires urgent investigation.

“Cryptorchidism is associated with several other male reproductive disorders including testicular cancer and infertility, which may result from reduced testosterone in males during fetal life. Therefore, these findings may also have implications for the current decline in male reproductive health in general.

“We have a moral duty to identify and eliminate the factors that are behind the recent increase in the incidence of male reproductive disorders.”



‘Time and spatial trends of operated cryptorchidism in France and environmental hypotheses: a nationwide study from 2002 to 2014’ by Le Moal et al was published in  Human Reproduction at 00:05 UK time on Wednesday 17th March.

DOI: 10.1093/humrep/deaa378


All our previous output on this subject can be seen at this weblink:


Declared interests

Prof Rod Mitchell: None

None others received.


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