From pathogens, biological drugs, illicit drugs to arsenic, by Prof Joe Cummins
An intact forest ecosystem protects and supplies the watershed
Photo © Craig Mackintosh
Unpolluted healthy drinking water is a right not a privilege. That right must be protected and restored to those suffering from shortages of drinking water or forced to consume polluted water. Water suppliers must fully and truthfully report findings of water pollutants even at levels deemed to be safe for human consumption by regulatory bureaucracies.
An estimated one billion people lack access to safe, reliable water supplies, and two billion people lack adequate sanitation. In the face of growing populations, climate change, and increasing transboundary water issues, conflict and even warfare over water have been widely predicted . Our goal must be to provide water security for all, especially for the poor everywhere.
Drinking water pollution poses immediate threats in developing countries that are different from those in developed countries. Parasites and pathogens are frequently associated with pollution of drinking water sources by faeces from humans and farm animals in developing countries. In addition, scarce groundwater sources are often contaminated by inorganic pollutants, primarily arsenic or fluoride, derived from geological sources. Pesticide contamination of drinking water is a significant problem in developing countries where, as the result of inadequate regulation, over 70 % of agrichemicals used intensively are banned or heavily restricted in the West.
Drinking water in the developed world is mainly contaminated by persistent organic pollutants along with pharmaceuticals derived from human and veterinary waste. The use of ‘second hand’ water following sewage treatment along with the growing requirements that groundwater must be recharged with such water poses a special concern. In North America, global warming has brought the scourge of the western pine beetle and frequent forest fires, contaminating the pristine watersheds with breakdown products of dead trees and aromatic hydrocarbons produced in the forest fires.
Drinking water pollution in the developing world
Drinking water pollution in developing countries is directly influenced by inadequate hygienic practices. In many countries of sub-Saharan Africa and Southern Asia, sanitation coverage is below 50 %. This facilitates the spread of pathogens and parasites resulting in debilitation and death . The Bill and Melinda Gates Foundation targeted the provision of robust and low cost sanitation technologies worldwide. It issued a challenge to universities to design toilets that can capture and process human waste without piped water, sewer or electrical connections, and transform human waste into useful resources, such as energy and water, at an affordable price . Prestigious Universities including California Institute of Technology, University of Toronto, Cranfield University have produced prototypes such as ones using solar energy to vaporize and recover water from faeces while converting the solids to biochar or fertilizer . Presently the numerous prototypes have not yet been tested in the field where some may prove effective.
Drinking water is a major source of microbial pathogens in developing regions, although poor sanitation and polluted food sources are the main routes of enteric pathogen exposure. Gastrointestinal disease outcomes are also more severe due to under-nutrition and lack of intervention strategies.
Poor water quality, sanitation and hygiene account for some 1.7 million deaths a year world-wide (3.1 % of all deaths), mainly through infectious diarrhoea. Nine out of 10 such deaths are in children and virtually all of the deaths are in developing countries. Major enteric pathogens in children include rotavirus, Campylobacter jejuni, enterotoxigenic Escherichia coli, Shigella spp. and Vibrio cholerae O1, and possibly enteropathogenic E. coli, Aeromonas spp. V. cholerae O139, enterotoxigenic Bacteroides fragilis, Clostridium difficile and Cryptosporidium parvum. All except Cryptosporidium are easily control by chlorination of water; while chlorination will save lives in epidemic outbreaks, it requires technical sophistication to avoid poisoning and toxic by-products. Pathogens, such as Helicobacter pylori and Burkholderia pseudomallei are significant pathogens in a number of areas. In adults, various sequellae such as myocarditis, diabetes, reactive arthritis and cancers follow some months to years after initial infections . For the most part these pathogens are maintained through faecal contamination of the drinking water sources. However, animal as well as human faeces may contribute to the spread of many pathogens, so for that reason the Gates Foundation focus on human toilets provides a necessary but not a sufficient remedy to the spread of microbial diseases in drinking water.
Groundwater pollution with arsenic and fluoride
Arsenic contamination of groundwater occurs naturally, with high concentrations in deeper levels of groundwater. Over 137 million people in more than 70 countries are affected by arsenic poisoning of drinking water. Arsenic contamination of ground water is found in many countries throughout the world, including the USA, nevertheless the contaminant tends to be greatest in underdeveloped regions in Asia, India and South America . Extremely toxic levels of fluoride are found in arid and semiarid regions in Africa, Asia and North and South America .
Groundwater polluted with elevated arsenic and fluoride causes concurrent chronic poisoning in India, China, Bangladesh, Mexico and Argentina. Currently arsenic poisoning is treated using chelation and supportive care while there is no treatment for fluoride poisoning . In Bangladesh, 80 million people are affected by arsenic poisoning from well water and one in ten of these people will develop cancer from the exposure. Chronic arsenic exposure is linked to skin lesions, cancers, adverse reproductive outcomes, nerve disorders, and impaired cognitive outcome in children. Extensive cardiovascular effects are encountered in humans and maternal arsenic exposure results in miscarriage, small birth size and infant mortality and morbidity. Arsenic-affected people experience enormous social stigma as people regard it an infectious disease or a curse . Like arsenic, fluoride is gene toxic and nerve toxic while the most prominent effects include abnormal teeth enamel in children and deformity of limbs and spine . Arsenic- and fluoride-contaminated groundwater is a chronic burden particularly in developing countries, which have no alternatives to polluted drinking water or inexpensive and robust technology to purify the polluted water.
Surface water pollution
The pollution of surface waters such as rivers in the developing world is staggering. A direct comparison of the river water quality in developed and developing countries concluded : Based on pressures and impacts, it is evident that dissolved metal, organic, and faecal pollution in the rivers of developing countries are in a somewhat dreadful condition in comparison with the rivers of a developed country. A major contributor to the deterioration in the quality of surface waters is pesticide pollution. Pesticide contamination of drinking water is a significant problem in developing countries, where over 70 % of agrichemicals used intensively are banned or heavily restricted in the developed world .
Drinking water pollution in the developed world: The Stockholm Convention
The main focus of concern over drinking water in developed countries has been persistent organic pollutants (POPs). Persistent organic pollutants (POPs) are targeted by the Stockholm Convention for reduction and eventual elimination from production, trade and release. All POPs share properties that make them long-lived (persistent), getting enriched along the food chains (bioaccumulative), present at elevated concentrations in remote locations (prone to long-range transport) and elicit adverse effects (toxic). Since its adoption on 22 May 2001, the Convention has identified just over 20 chemicals and groups of compounds as POPs. These include the original ‘dirty dozen’ compounds as the coming into force of the convention (aldrin, chlordane, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, toxaphene, DDT, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls), followed by another nine compounds in 2009 (chlordecone; hexabromobiphenyl; tetra-, penta-, hexa- and hepta bromodiphenylether; a-hexachlorocyclohexane; ß-HCH; HCH (lindane); pentachlorobenzene; perfluorooctane sulfonic acid, its salts and perfluorooctane sulfonyl fluoride). In 2011, endosulfan was added to the list .
The Stockholm Convention on Persistent Organic Pollutants was adopted at a Conference of Plenipotentiaries on 22 May 2001 in Stockholm, Sweden, and entered into force on 17 May 2004. The Convention prohibits or takes legal administrative measures to eliminate the listed chemicals and to forbid import or export of the chemicals. The Convention has been ratified by all but a few African nations, Pakistan, Afghanistan and the United States . Guidelines for a number of pesticides and industrial chemicals that are not considered persistent are provided by the World Health Organization (WHO) . However, WHO does not consider the pesticide glyphosate among a number of other widely used pesticides hazardous and does not provide a guideline. In contrast, US EPA  and the Canadian Government provide guidelines in the face of growing evidence that the herbicide encountered in groundwater and drinking water and has been found to be toxic to both animals and humans (see  Why Glyphosate Should Be Banned, ISIS Special Report).
Pharmaceuticals in drinking water
Among the licit drugs identified in water supplies are antibiotics, analgesics and anti-inflammatories, beta-blockers, hormones, statins, selective serotonin reuptake inhibitors antiepileptic, diuretics, anti-asthmatics, antidepressants, antineoplastic, antipsychotics, stimulants, sedatives, and anticoagulants. Pharmaceuticals are synthetic or natural chemicals found in prescription medicines, over-the counter therapeutic drugs and veterinary drugs. The ubiquitous use of pharmaceuticals (both prescribed and over the counter) has resulted in the continuous discharge of pharmaceuticals and their metabolites into wastewater. They are introduced through sewage, which carries the excreta of individuals and patients who have used these chemicals, from uncontrolled drug disposal (e.g. discarding drugs into toilets) and from agricultural runoff in livestock manure. In addition, pharmaceuticals may be released into water sources in the effluents from poorly controlled manufacturing or production facilities.
There is clear and substantive evidence that pharmaceuticals in water do impair aquatic organisms and the genotoxicity of both the pharmaceuticals and their breakdown products are likely to be injuring people and causing impairment of the nervous system. For example, gene expression patterns were examined with microarrays in the brain of fathead minnow fish treated with a mixture of three psychoactive pharmaceuticals (fluoxetine, venlafaxine &carbamazepine) in dosages intended to be similar to the highest observed conservative estimates of environmental concentrations. Only the sets of genes associated with idiopathic autism were unambiguously enriched. Unmetabolized psychoactive pharmaceuticals induce autism-like gene expression patterns in fish. This may well have implications for human autism (see  Pharmaceutical Cocktails Anyone?, SiS 56).
Illicit Drugs in Drinking Water
Illicit drugs and their metabolites in the environment and their potential impact on the ecosystem is a growing concern. Cocaine, morphine, amphetamine, and MDMA have potent pharmacological activities and their presence as complex mixtures in water may well have adverse effects on aquatic organisms and human health. However, there is no regulation over the presence of these pollutants in treated wastewater, surface water, drinking water, or the atmosphere. Extensive reviews from around the world have documented widespread pollution of water by illicit drugs. The data provide information on drug abuse that cannot be obtained from conventional epidemiology. Even more importantly, they highlight the need for remediation in order to restore the quality of urban drinking water. Drinking water polluted with illicit drugs has been deemed acceptable by government agencies including the WHO, the European Union and the US Environment Protection Agency, in clear violation of the precautionary principle with regard to public health and safety.
For example, the amphetamine-based drugs are altered by drinking water chlorination to produce by-products that are more stable and genotoxic than the parent drug. Like pharmaceutical drug pollution, the levels observed are sufficient to affect aquatic organisms. Precaution demands that the public be alerted to the growing threat to drinking water. The locations where drinking water is polluted with illicit drugs should not be withheld from the population affected (see  Illicit Drugs in Drinking Water, SiS 56).
With both licit and illicit drugs it is alarming to realize that many of the drugs and their metabolites are very stable in the aquatic environment. In some cases water treatment by chlorination, active oxygen or ultraviolet light may reduce the level of the drug in treated water while producing by-products that are more stable and more toxic than the drug. The drugs are most commonly encountered in the form of mixtures which should be evaluated for synergism. It is worth mentioning that the employment of biological drugs, produced in genetically modified microbes or cell cultures derived from animals or humans, are becoming commonplace in vaccines, cancer therapy and for treatment of chronic diseases in human and veterinary medicine. The biological drugs tend to be active at very low concentration and the fate of the drugs or their by-products in wastewater and drinking water should be studied.
Climate-induced forest die-off
In many countries and regions, pristine water is supplied through forest watersheds to large populations. Global warming has caused the mountain pine beetle to kill vast areas of forests in western North America. The decaying dead trees in those forest watersheds are a unique pollution of the pristine waters. The by-products of the decaying trees have begun to appear at elevated levels in drinking water . Furthermore, the blighted forests are prone to spread fire over large areas, leaving behind aromatic hydrocarbons which seep into the water supply.
Pristine drinking water has begun to disappear from the planet. We must depend more and more on recharged groundwater and purified waste water. The Gates Foundation’s focus on reinventing the toilet may uncover a modern Thomas Crapper who made flushing popular. But that is not enough. Simple and inexpensive technology for freeing water of its organic and inorganic pollutants should be the basis of a competition similar to the Gates reinvention of the toilet. In order to cope appropriately with the growing poisoning of our drinking water supply we should demand full and truthful reporting of all tests done on our drinking water, and above all, regulators should make every effort to reduce pollution at source.