Forensic toxicology in urban South Africa

Profile and outcome of patients presenting with agrochemical poisoning to the emergency department

Background:

Deliberate self-harm (DSH) is one of the leading causes of mortality and morbidity in India. Agrochemicals are the most commonly used compounds for DSH. The spectrum of Agrochemicals in use varies from region to region and time period with newer compound being regularly introduced into the market.

Methodology:

This retrospective cohort study included patients presenting with agrochemical poisoning to the ED during January 2017 to December 2018. Patient data was retrieved form the ED triage registry software and clinical workstation, following which their hospital outcome was determined.

Results:

During the study period, 1802 patients presented with DSH among which Agrochemical poisoning comprised 33.5% (604/1802). The mean age was 31 years and incidence of agrochemical poisoning was found to be higher in young adults (16–30 years–55.8%). The prevalence was more common in males (62.4%). The common agrochemical compounds consumed were insecticides (91%), herbicides (4.3%), fungicides (1.5%), fertilizer (1.5%), and plant growth regulators (1.5%). Majority (80.96%) of the patients were discharged alive from the hospital, 17% left against medical advice due to bad prognosis and 12 patients (2%) died in the hospital.

Conclusion:

Insecticides (mainly Organophosphates) are the most common agrochemicals used for DSH. Their management is better understood leading to better outcomes compared to other chemicals. The proportion of agrochemical use in DSH has reduced over the last decade. Imidacloprid (Insecticide) and Plant growth regulators are the new compounds for which appropriate management is not yet established and more research is needed.

Agrochemical Poisoning

A general increase in the use of chemicals in agriculture has brought about a concomitant increase in the incidence of agrochemical poisoning. Organophosphates are the most common agrochemical poisons followed closely by herbicides. Many agricultural poisons, such as parathion and paraquat are now mixed with a coloring agent such as indigocarmine to prevent their use criminally. In addition, paraquat is fortified with a “stenching” agent. Organo-chlorines have an entirely different mechanism of action. Whereas organophosphates have an anticholinesterase activity, organochlorines act on nerve cells interfering with the transmission of impulses through them. A kerosene-like smell also emanates from death due to organochlorines. The diagnosis lies in the chemical identification of organochlorines in the stomach contents or viscera. Organochlorines also resist putrefaction and can be detected long after death. Paraquat has been involved in suicidal, accidental, and homicidal poisonings. It is mildly corrosive and ulceration around lips and mouth is common in this poisoning. However, the hallmark of paraquat poisoning, especially when the victim has survived a few days, are the profound changes in lungs. Other agrochemicals such as algicides, aphicides, herbicide safeneres, fertilizers, and so on, are less commonly encountered. Governments in most countries have passed legislations to prevent accidental poisonings with these agents. The US government passed the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) in 1962 and the Indian government passed The Insecticides Act in 1968. Among other things, these acts require manufacturers to use signal words on the labels of insecticides, so the public is warned of their toxicity and accompanying danger.

Position of immunological techniques in screening in clinical toxicology

There is a continuing increase in the use of immunological techniques in the field of clinical toxicology. This is primarily due to the rapidity by which analytical results are now required, and can be obtained, following the testing of individuals for drug use. There has recently been an increase in the repertoire of assays now available to testing laboratories (e.g., buprenorphine and heroin metabolite assays), with the techniques themselves becoming increasingly more specific for the drugs and/or metabolites being monitored (e.g., methadone metabolite assays). The near patient testing (NPT), or point-of-care testing (POCT), devices are now several generations forward from their inception, with some tests now approaching the sensitivity and specificity of automated laboratory-based methods. This review has been collated from the literature to illustrate some of the possible reasons for the move towards the increasing use of immunological techniques, and to highlight some of the advantages and disadvantages associated with such drug screening methods. In particular, it has been shown that it is important to determine, monitor and review the knowledge and training of the individual using the technique. In addition, quality control and quality assessment are paramount to ensure the validity of any drug testing being performed. It has also been shown that it is vital to maintain and develop the relationships between the staff performing the testing, the laboratory (if the testing is performed using NPT devices), and the clinicians utilising the results obtained from drug testing. Without these links, interpretive errors could arise which could adversely affect the diagnosis and management of patients.

South Africa: a toxicologist's goldmine

The emerging nation of South Africa, in common with some other countries, notably Eastern Europe, is heir to decades of neglect with regards to the exposure of the majority of its population to toxic materials. In this short review, the major toxic health hazards are described. For most of these risks there are now programs in place to improve the situation, but co-ordination and financial constraints, along with the fact that the majority of the population neither live, nor work, in a controlled environment, mean that much remains to be done. The recent formation of a South African Toxicology society, which strives to bring together environmental, industrial, forensic and clinical toxicology should assist in an improvement, both in the epidemiology of toxicity in South Africa and in improved measures to reduce the incidence of preventable noncommunicable diseases related to both acute and chronic exposure to toxins. The South African scene also provides a "window' of opportunity to study the more fundamental aspects of exposure in human subjects and to couple these to animal and in vitro studies to elucidate the underlying mechanisms where these are unknown.

Metal concentrations in plants and urine from patients treated with traditional remedies

A number of traditional South African herbal remedies which are associated with morbidity and mortality were analysed for selenium, manganese, copper, lead, zinc and mercury content. Few showed high levels of toxic metals, but in these the concentrations were sufficiently high as to cause concern since there is no quality control on the production of these remedies, which are the accepted form of medication for over 80% of the population. Urine samples, obtained from 65 patients admitted to hospital following treatment with a traditional herbal remedy were also analysed for metals. Only a small number of the patients had abnormally high levels of metal excretion. These data suggest that, in contrast to experience with traditional Chinese and Indian preparations, metal contamination from plants seems not to be a problem in traditional South African remedies.