Henk A. Tennekes graduated from the Agricultural University of Wageningen, The Netherlands, in 1974, and performed his Ph.D. work on the carcinogenicity of the insecticide dieldrin at Shell Research Ltd in Sittingbourne in the UK. He worked at the German Cancer Research Centre in Heidelberg from 1980 - 1985 (and mentored by renowned oncologist Hermann Druckrey) and was Chief Toxicologist at RCC Research and Consulting Company AG, a maj or contract research organisation in Switzerland from 1986 - 1992.

In 1992, Dr. Tennekes established an independent consultancy for product safety assessment, ETS Experimental Toxicology Services BV, which has served leading companies in the chemical industry over the past two decades, with an excellent record of achievement.
Dr. Tennekes was Secretary of the Toxicology Section of the Swiss Society of Pharmacology and Toxicology from 1992 - 1998 and a Member of the Board of Directors of the Swiss Register of Toxicologists from 1996 - 2000.
Henk Tennekes has authored important papers in the field of toxicological research, most recently a chapter in a text book on Cancer Risk Assessment, published by John Wiley & Sons.

The culmination of Dr Tennekes' research was his recent discovery (Toxicology 2010: 276, 1-4) that the relationship between exposure concentration and lethal effect in arthropods for a new generation of insecticides, the so-called neonicotinoids, has much in common with that established by Druckrey for genotoxic chemical carcinogens-cancer-causing agents, the implication being that very stringent risk asessment procedures would have to be applied to a category of pesticides used all over the world in intensive agriculture. In particular, he inferred that the risks associated with longer term exposure of invertebrates to the low concentrations of these persistent pesticides prevailing in the environment had been seriously underestimated.
When he realized the dire consequences of environmental pollution with these insecticides, i.e., the possible extinction of the invertebrates such as honey bees and butterflies, and, consequently, of invertebrate-dependent species, such as fish, birds, amphibians, reptiles, and mammalian species (e.g. bats, hedgehogs, non-human primates), he decided to write the now famous book “The Systemic Insecticides: A Disaster in the Making”, published in November 2010, to warn the general public about an impending environmental catastrophe. His groundbreaking work played an important role in bringing about partial bans on neonicotinoids in Europe.

Memberships & certifications


  • Dutch Society of Toxicology:
  • Swiss Society of Pharmacology and Toxicology:
  • British Toxicology Society:
  • Association of European Toxicologists and Toxicological Societies (EUROTOX):
  • International Union for the Conservation of Nature (IUCN)/Commission on Ecosystem
    Management (CEM)
  • Society of Toxicologic Pathology
  • American Chemical Society
  • Overseas Fellow, Royal Society of Medicine

Memberships Editorial Board Scientific Journals:

  • Editor-in-Chief, Journal of Environmental Risk Assessment and Remediation
  • Editorial Board Member, Annals of Clinical Toxicology
  • Editorial Advisory Board Member, The Open Toxicology Journal
  • Editorial Board Member, Toxicology: Current Research Journal
  • Editorial Board Member, Journal of Cancer Research Forecast


  • Registered Toxicologist in Switzerland and the Netherlands (with EUROTOX certification)




1968 - 1974: Student at the Agricultural University of Wageningen,The Netherlands. M.Sc. degree in Human Nutrition awarded in 1974.
1974 - 1978: Ph.D. Student, Shell Toxicology Laboratory in Sittingbourne, United Kingdom.
1979: Ph.D. degree in Agricultural Sciences awarded by the Agricultural University of Wageningen, The Netherlands, on a thesis entitled "The Relationship between Microsomal Enzyme Induction and Liver Tumour Formation" (under supervision of Prof. Dr. J. H. Koeman).

Professional Experience

1978 - 1980: Scientist at the Institute of Toxicology and Pharmacology of the University of Marburg, Germany.
1980 - 1985: Scientist at the German Cancer Research Center in Heidelberg, Germany.
1985 - 1986: Senior Toxicologist in the Department of Agrochemical Toxicology of Sandoz Ltd in Muttenz, Switzerland.
1986 - 1992: Head of the General Toxicology Department and Member of the Directorate at RCC, Research and Consulting Company Ltd in Itingen, Switzerland.
1992 - present: Independent Consultant in Toxicology in Pratteln, Switzerland (1992 - 1998) and Sissach, Switzerland (1998-2002), now based in Zutphen, the Netherlands.


1974 - 1985 Mechanistic research on the induction of mouse liver tumours by non-genotoxic compounds. The organochlorine insecticide dieldrin served as a model substance. The most important results of these investigations were:

  • The demonstration in a chronic mouse study of a relationship between dieldrin-induced increases in liver DNA and mouse liver tumour formation [Cancer Research 41, 3615-3620 (1981)];
  • The elucidation, in mathematical terms, of the dose-response relationship of a non-genotoxic carcinogen [Carcinogenesis 6, 1457-1462 (1985)];
  • The demonstration of a close association of tumour formation with nuclear polyploidisation in mouse hepatocytes [Carcinogenesis 8, 265-269 (1987)].
1985 - 1992 Direction of numerous general toxicity and carcinogenicity studies with pharmaceuticals and agrochemicals. Successful management of the general toxicology department of a major European contract research laboratory leading to rapid expansion of services. First introduction in the world of computerised dosing equipment in general and reproduction toxicity studies in 1988.
1992 - present

Consultancy services to leading companies in the chemical industry with an acknowledged record of achievement. The consultancy offers comprehensive services in product safety assessment including: Design of safety evaluation programmes, Human safety assessment, Interaction with regulatory agencies (product defense), Preparation of EU expert reports and US NDAs, Preparation of preclinical assessments, investigator’s drug brochures, INDs, Data interpretation and evaluation (report preparation), Design, monitoring and report review of toxicity studies, Preparation of manuscripts for publication in scientific journals (including editorials), Coaching and training of junior toxicologists, Presentations in Radio and TV programmes/documentaries.

1992 - 1998 Secretary of the Toxicology Section of the Swiss Society of Pharmacology and Toxicology.
1996 - 2000 Member of the Board of Directors of the Swiss Register of Toxicologists.
1995 Chairman of the Task Force of the Swiss Society of Pharmacology and Toxicology on Guidelines for Training and Registration of Toxicologists in Switzerland. The recommendations of the Task Force were adopted by the Society for the establishment of a Swiss Register of Toxicologists (with EUROTOX certification) and a post-graduate training programme for toxicologists in Switzerland.
2002 - 2004 The demonstration in outbred and inbred rat strains that (spontaneous) carcinogenesis is genetically determined and that non-genotoxic carcinogens operate by facilitating the expression of tumour predisposition in target cells [Regulatory Toxicology and Pharmacology, 36, 86-95; 40, 18-27; 40, 293-304].
2009 - 2017 Discovery that the Druckrey-Küpfmüller equation d t n=constant (where d= daily dose and t = exposure time to effect, with n ≥ 1) for genotoxic carcinogens also applies to non-genotoxic compounds, such as the toxicity of neonicotinoid insecticides to arthropods (Toxicology, 276, 1-4).
Publication of books on the hazards of neonicotinoid insecticides to insects and the food chain.
Review of current pesticide risk assessment and proposals for new approaches (Toxicology 309, 39–51; J Environment Analytic Toxicol S4:001; Sci. Rep.4, 5566; DOI:10.1038/srep05566 (2014)) that were subsequently adopted by the European Food Safety Authority (EFSA). Instrumental role in bringing about bans on neonicotinoids in Europe. Proposed novel approaches to chemical risk assessment in a special issue of the Journal of Environmental Risk Assessment and Remediation.