The international equality-in-sport charity, equitysport (equitysport.org) call for the immediate suspension of World Athletics female eligibility regulations pending a fully independent review into their scientific basis.

On Tuesday 17th August, 2021, the British Journal of Sports Medicine (BJSM) published a correction to the 2017 research paper which underpins World Athletics' eligibility regulations for female athletes.

The regulations, which came into force in 2018, only apply to women with particular variations in sex characteristics - referred by the governing body as DSD (Differences of Sexual Development), and require certain athletes to reduce their blood testosterone to a level specified by World Athletics.

These regulations have come under significant scrutiny for their impact on athletes' rights to non-discrimination, as well as the continued use of a single biological marker for determining sex.

The original 2017 paper argued a causal relationship between testosterone levels and athletic performance among women, but just for certain events. This happened to include events run by Caster Semenya, the South African runner targeted by the regulations, and more recently Christine Mboma and Beatrice Masilingi of Namibia.

We, at equitysport, have long held a position that these regulations and the requirement for particular athletes to engage in medically unnecessary interventions deny certain women an equal right to participate in sport. Our position fully supports the position of the United Nations Human Rights Council that the current sex-testing apparatus and criteria set by World Athletics and the IOC risk violating a number of human rights.

In the BJSM correction published on 17th August, World Athletics now admits that its claims to the scientific basis for the regulations, i.e. for the causal relationship between testosterone levels and athletic performance among female athletes in the restricted events, was incorrect.

"To be explicit, there is no confirmatory evidence for causality in the observed relationships reported. . . With this in mind, we recognise that statements in the paper could have been misleading by implying a causal inference."

World Athletics, for its part in the correction, has called for an independent scientific review to "establish confirmatory scientific evidence for the causal relationship between the variables analysed."

Without confirmatory scientific evidence, there is no justification for the continued application of the World Athletics female eligibility regulations and we, the undersigned, call for the following steps to be actioned immediately by World Athletics:

1. An immediate independent review of the scientific claims found within the World Athletics DSD regulations should be undertaken by an authoritative organisation completely independent to World Athletics and the International Olympic Committee.

2. While such a review is taking place, the World Athletics female eligibility regulations should be suspended, with immediate effect.

3. The full results of the independent review must be made public at the earliest opportunity.

With thanks to Roger Pielke Jr. for his assistance in constructing this open letter.