Abstract
The 7th Congress of Toxicology in Developing Countries (7CTDC) was held in 6-10 September 2009 in Johannesburg, South Africa. This is the second CTDC held on the African continent where the first was held in Egypt in 1996 1 . The aim of these series of congresses is to discuss toxicological issues relevant to developing countries. The participation of scientists from developed countries is encouraged with the hope of bridging the gap in toxicological issues between developed and developing countries. These in mind, the topics discussed at the 7CTDC concentrated on themes that will help in harmonisation of toxicology issues between developed and developing countries, particularly in the areas of toxicity testing, environmental pollutants, biological monitoring, food safety, risk assessment as well as in regulatory requirements as accepted in developed countries. It is hoped that with this exercise, knowledge gained in toxicology in developed countries is transferred, through capacity building, to developing countries to help reduce the burden of exposure to toxic substances and decrease their adverse effects through adequate management.
Some of the issues identified that need to be addressed in developing countries are exemplified in the scientific papers selected for publication in this special issue of Human and Experimental Toxicology. An article by Gelderblom and Marasas discusses the controversies in the risk assessment of fumonosins, fungal toxins some of which express carcinogenic potential. 2 The authors argue that setting of two tolerable daily intake (TDI) values by international agencies, one based on carcinogenicity and the other on nephrotoxicity, may be a source of concern: Implementing the TDI based on carcinogenicity may impact negatively on international trade in this commodity; implementing the TDI based on nephrotoxicity may impact negatively on human health especially in countries where consumption of food such as maize as a staple diet, is very high. In a country such as South Africa, the predicted daily intake (PDI) levels of fumonisins in certain regions exceed 5-10 times above the PMTDI and hence the urgency of setting new PMTDI levels for this carcinogen in developing countries is advocated.
Medicinal plant extracts are widely used in developing countries to treat different ailments. The efficacy of number of plant extracts is therefore discussed by two research groups: one from South Africa and the other two collaborating laboratories from Nigeria and Brazil. The first by Cordier et al. investigates number of plant extracts for blood-associated complaints. 3 The second work by Adebayo et al evaluates in vitro the husk fibres of four variety of C. nucifera for their antimalarial activity. 4 A challenge for the future is to be able to identify the active chemical species in these plant extracts so that the treatments can be applied even more safely. This knowledge would also allow the harmonization and improvement of the quality of the plant extracts.
As an example of narrowing gaps in knowledge between developed and developing countries, IUTOX has embarked on an exercise in establishing the World Library of Toxicology (WLT) in order to make global toxicology information more readily accessible. The authors, Wexler et al, elaborate on this exercise and give detailed account on future ahead for expansion. 5
Finally, there are articles on biomonitoring, a major theme discussed at the congress, which presented by two research groups. In the first article, Avila et al. explores the suitability of Caenorhabditis elegans as a reliable tool for biomonitoring of environmental toxicants. 6 Due to its short-life span, low cost maintenance, extensively studied nervous system, and high evolutionary conservation with higher eukaryotes, these authors argue in favour of its use as a model for neurotoxicity in the assessing the toxic effects of commonly encountered environmental pollutants in developed and developing countries including manganese, methyl mercury, uranium, and pesticides. The other two articles presented by the same group, explore possible biomarkers of exposure to tobacco constituents and also to organophosphates. In the article by Tzatzarakis et al, the authors investigate the use of hair nicotine/cotinine for monitoring of exposure to tobacco during infancy and adulthood. 7 An association could be found between the level of these biomarkers and heavy exposure to second hand smoke in infants. The second article by Tsatsakis et al investigates the possibility of using dialkyl phosphate metabolites in hair segments as a biomarker of acute exposure to organophosphates. 8
Risk assessment, toxicity evaluation methodologies, need for training and sharing knowledge as well as search for biomarkers to assess exposure are all toxicological issues of concern for both developed and developing countries. Reliance of developing countries on developed countries to determine acceptable standards for exposure and the search for biomarkers to toxic compounds that may be more prevalent in developing countries, are examples of necessary joint approaches of both developed and developing countries to solve current toxicological issues. Availability of expertise in the discipline of toxicology, or the lack of it, may determine approaches in solving the present toxicological issues in developing countries. The very different challenges of toxicological issues, and the usefulness of capacity building in toxicological risk assessment in developing countries, justifies holding the CTDCs to assist in narrowing the existing gaps between developed and developing countries in toxicology, and hence harmonise the manner in which these similar toxicological issues are addressed.