Secondary prevention of CSEM

Secondary prevention of the use of online child sexual exploitation material (CSEM): an initial overview of international efforts


This 2PS article presents the content of a german publication focused on the prevention of the use of CSEM.

Specifically, it focuses on showcasing some of the psychosocial intervention offerings, with the intention of sharing expertise and initiatives in the field of preventing child sexual abuse, especially in the German-speaking region, without aiming for comprehensive coverage. Instead, it represents collaborative efforts from various European consortia to contribute knowledge through selected case studies.

See the original source.



In 2022, the Internet Watch Foundation (IWF) tracked 375,230 reports of online child sexual abuse imagery, with 68% classified as sexually abusive material. This is likely representing just the tip of the iceberg.

Europol’s 2021 assessment highlighted a significant problem of child abuse images on the internet, noting a rise in their profitability. During the pandemic, the IWF reported a 374% increase in “self-created” abusive images.



Categorisation of interventions


Interventions against sexual offenses are categorised into four levels:

  1. primary prevention, targeting the general population or potential victims to prevent the onset of offenses;
  2. secondary prevention, focusing on identifiable risk groups of potential offenders or victims;
  3. tertiary prevention, aimed at those who have already committed offenses to prevent recidivism;
  4. quaternary prevention, addressing individuals who have undergone rehabilitation to mitigate negative consequences and reduce the impact of criminalization.

Additionally, a fifth level, primordial prevention, aims to prevent the development of risk factors from the outset.

Non-governmental organizations play a crucial role in supporting secondary and tertiary prevention efforts, particularly with individuals at risk of committing or escalating to sexual offenses or those who have committed such offenses.



European efforts to prevent the use of CSEM


The European Union has made significant efforts to prevent and combat child sexual abuse and exploitation, and the consumption of Child Sexual Exploitation Material (CSEM).

Specifically, the European Commission has developed criteria for the prevention of sexual abuse and exploitation of children.  Academics, policymakers, and professionals in the field participated in the discussion and development.

These criteria aim to improve understanding, classification, and policy development.

This work underscores the shared European commitment to preventing the consumption of abusive imagery, with a focus on the evaluation of programs and the treatment and support of individuals convicted of sexual offenses.



Secondary prevention of the use of CSEM


The cited article distinguishes between secondary preventive deterrence and the elimination of opportunities at the law enforcement level and more complex psychosocial interventions.

Law enforcement authorities play a crucial role in the secondary prevention of Child Sexual Exploitation Material (CSEM) consumption through preventive deterrence and supporting NGOs.



Preventive deterrence


They employ preventive deterrence methods at technological, societal, and international levels to restrict access and distribution of CSEM. This includes the analysis of linguistic indicators of interest in CSEM content.

Organizations like Thorn have developed tools such as the Child Sexual Abuse Material Keyword Hub to provide a list of search terms associated with CSEM content. This allows to enable online platforms to detect and prevent harmful content.

Additionally, preventive deterrence includes the use of CSEM-specific hash sets. They are mathematical algorithms to identify identical or similar content. Hashing is used as an early detection system to prevent the uploading of CSEM. Additionally, it helps identify known material during investigations.

Organizations like the National Centre for Missing and Exploited Children (NCMEC) and the Internet Watch Foundation (IWF) maintain hash databases for deterrence. They cooperate with international partners to distribute these hash sets, preventing the addition of CSEM and aiding law enforcement in investigations.



Proactive deterrence


Even proactive deterrence plays a crucial role in combating online child sexual abuse.

It involves identifying CSEM websites, determining their hosting source, and issuing notices to remove the content.

Organizations like the Internet Watch Foundation and INHOPE work with international partners to identify CSEM websites and have them taken down. The INHOPE-ICCAM program has been responsible for identifying and removing potentially illegal CSEM content from the internet, making a significant impact.

In the United States, the NCMEC is leading non-governmental organization for receiving, processing, and forwarding CSEM reports to law enforcement worldwide. These reports help identify and protect victims of child sexual abuse.

However, the increasing prevalence of CSEM-related offenses poses significant challenges for law enforcement. Addressing the problem solely through arrests is not sufficient.

Instead, law enforcement agencies need to establish preventive deterrence programs to reduce harm, emphasizing tertiary prevention for individuals already convicted and secondary prevention for those at risk.



Effective intervention programs


Collaboration between law enforcement and non-governmental organizations is critical in the fight against CSEM. However, a more systematic understanding of effective intervention programs is needed for a comprehensive response to CSEM.

In 2018, the Centre of Expertise on Child Sexual Abuse published a review outlining the intervention landscape for individuals involved in child sexual abuse offenses on the internet.

The study aimed to examine existing evidence of effectiveness, identify current gaps in intervention offerings, and highlight future challenges in this area. The review included a comprehensive search for intervention providers through literature research and direct inquiries. It also conducted an online survey of these providers, and detailed interviews with experts.

The search yielded 48 NGOs, 16 of which offered psychosocial interventions primarily for individuals (mostly men) who had identified inappropriate sexual behavior or fantasies in themselves or had been referred due to CSEM-related offenses.

The remaining 32 organizations contributed to prevention, such as content removal, victim protection, and tertiary prevention. Some organizations indirectly supported the intervention landscape through research or public education. Others were international organizations focused on child protection, with their work against CSEM falling within their broader child protection mandate.




Merdian, H.L., Allardyce, S., DeBoeck, M. et al. Sekundärprävention der Nutzung von Kindesmissbrauchsabbildungen im Internet: ein internationaler Überblicksversuch. Forens Psychiatr Psychol Kriminol 17, 377–388 (2023).


Written by Viola Westfal, Institute of Sexology and Sexual Medicine, Charité – Universitätsmedizin Berlin