To produce a new commented edition of Cicero's Catilinarians may seem like a woefully unoriginal, if not altogether superfluous undertaking. There are, of course, various commentaries, mostly of nineteenth- and early twentieth-century vintage, intended to introduce this corpus to school children. But in the latter half of the twentieth century interest in producing such works tapered off as the traditional classical curriculum came under fire and lists of set books were altered in the hope of reinvigorating the subject. In addition, the palpable decline of oratory in the political life of the Western democracies made C.'s products seem less relevant to contemporary concerns. Last, but not least, the negative assessment of C. by W. Drumann and T. Mommsen has often colored the judgment of subsequent historians of antiquity and thus fed a neglect of, if not outright hostility to, C. and his work.

The fact that his place in the curriculum can no longer be taken for granted may prompt some salutary reflection on C. and his educational uses. Blind hero-worship is clearly inappropriate, as Petrarch already realized upon discovery of C.'s letters. But the fact that C., too, was human makes him more, not less interesting. His creation of a distinctive and powerful prose style exploiting to the full the resources and registers of the Latin of his day commands, or should command, admiration in an age when language and style tend to be handled carelessly.

CATILINE'S CAREER DOWN TO 63

For most of his life, Lucius Sergius Catilina, or Catiline, as he has come to be known in English, looked like anything but a revolutionary. He was the scion of an old patrician family, the gens Sergia, which gave its name to one of the Roman tribes; and Virgil glorified, if he did not invent altogether, an eponymous ancestor, Sergestus, as one of the Trojan heroes who migrated to Italy with Aeneas (Aen. 5.121). Even his adversary C. was able, in the very different context of a lawcourt speech, to express a certain appreciation for the attractive features of Catiline's many-faceted personality (Cael. 12–14).

Catiline's great-grandfather, M. Sergius Silus, had distinguished himself in the Hannibalic War (without, however, rising above praetorian rank). As praetor of the year 68, Catiline must have been born by 108 (or 106 on the assumption that patricians had the option of presenting themselves two years early). He substituted an individual cognomen for the inherited Silus but followed the family tradition of military service. The beginnings of his military career are lost unless he is to be identified with the L. Sergius L.f. attested as a member of the consilium of the consul Cn. Pompeius Strabo in 89 during the Social War.

Odour and taste

Considerable odour and taste problems develop while the water is in the distribution system due to the material from which the mains are constructed, or the effect of biological growths on the walls of the pipes. However, most problems originate either in the raw water (Chapter 8) or from the treatment plant (Chapter 16). The water supply company is careful to eliminate these as possible sources of odour before testing the water within the distribution system to isolate the problem area (Figure 8.1).

The major complaint arising from the distribution system is that of musty–earthy odour (Figure 8.2). These are due to the development of micro-organisms on the walls of the distribution network. Although actinomycetes and fungi are generally responsible, heterotrophic bacteria can also cause similar problems if present in large numbers. This suggests that a high activity of any micro-organism, regardless of its identity, may result in odours. A number of steps can be taken to reduce microbial growth within the distribution system, the main one being to ensure adequate disinfection with sufficient residual chlorine. Other methods include reducing the amount of organic matter and nutrients in the water by more effective treatment (Chapter 14) and using new pipe materials that do not encourage microbial development. The growth of actinomycetes and fungi is controlled primarily by temperature, with optimum growth occurring at 25°C. At temperatures below 16°C growth is so reduced that complaints due to odour are generally eliminated. It is therefore essential to prevent water in distribution systems from standing for long periods and warming up. During warm weather conditions it is possible for many supplies to reach ambient temperatures as a consequence of this long residence time, thus encouraging the unwanted growth of micro-organisms. Long residence times also encourage organic material to flocculate and settle, which then acts as a source of food for micro-organisms and small animals (Chapter 24).

Iron

Iron is an extremely common metal and is found in large amounts in soil and rocks, although normally in an insoluble form. However, due to a number of complex reactions that occur naturally in the ground, soluble forms of iron can be formed, which can then contaminate any water passing through. Therefore excess iron is a common phenomenon of groundwaters, especially those found in soft groundwater areas.

Iron is an essential element and is very unlikely to cause a threat to health at the concentrations occasionally recorded in water supplies. It is undesirable in excessive amounts and can cause a number of problems. Iron is soluble in the ferrous state (Fe2+) and is oxidized in the presence of air to the insoluble ferric form (Fe3+), so when groundwaters are anaerobic, or have low dissolved oxygen concentrations, all the iron will be in a soluble form. Oxygen can enter aquifers via boreholes. This, combined with the removal of carbon dioxide from solution, raises the pH and causes iron in the groundwater to precipitate out as ferric hydroxide (solubility threshold pH 4.2). Even small changes in water chemistry can affect iron solubility, and the conditions in many groundwaters are on the boundary between soluble and insoluble iron (Figure 9.1). At the treatment plant most of the iron is removed by aerating the water or by using coagulants, with the particles of insoluble iron removed by filtration. In private supplies the water will only start to become aerated as it enters the storage tank. Here the ferric iron particles will settle to the bottom of the tank and form an orange sediment, which can then be re-suspended when large volumes of water are being drawn from the tank. Alternatively, as the water leaves the tap it is very effectively aerated and it is here the water may become discoloured and turbid. Sediment will also form in the pipe-work and this will contribute to the discolouration of the water.

Introduction

The fluoridation of water supplies has been as controversial in the past as trace organics in water is today. It was introduced in the 1940s to reduce the incidence of tooth decay in the population after a number of surveys in the USA had shown that it had a beneficial effect. Three relationships were identified: (1) fluoride levels in excess of 1.5 mg 1−1 led to an increase in the occurrence and severity of dental fluorosis (i.e. teeth became mottled and brittle) without decreasing the incidence of decay, missing or filled teeth; (2) at 1.0 mg 1−1 there was the maximum reduction of decay with no fluorosis; and (3) at concentrations less than 1.0 mg 1−1 some benefit was observed. With decreasing concentrations of fluoride in water there was an increase in the incidence of tooth decay.

These studies therefore showed that the addition of fluoride to water supplies to bring the level above 0.6 mg 1−1 led to a reduction in tooth decay in growing children, and that the optimum beneficial effect occurred around 1.0 mg 1−1. Other studies have indicated that fluoride is also beneficial to older people in reducing the hardening of the arteries and, as fluoride stimulates bone formation, in the treatment of osteoporosis, although the most recent evidence contradicts this (Cooper et al., 1990). These early studies were so convincing that fluoridation was adopted around the world, so that today over 250 million people drink artificially fluoridated water. In the USA, for example, over half of the water supplies are fluoridated. It is widely used in New Zealand, Canada and Australia; in fact, it is widespread in most English-speaking countries. Brazil and the former Soviet Union are two other countries with a strict fluoridation policy. In the Republic of Ireland all water supplies are fluoridated where the natural levels are less than 1.0 mg 1−1, none are fluoridated in Northern Ireland and only about 10% of supplies are fluoridated in the UK.

Introduction

The hardness or softness of water varies from place to place and reflects the nature of the geology of the area with which the water has been in contact. In general, surface waters are softer than groundwaters. Hard waters are associated with chalk and limestone catchment areas, whereas soft waters are associated with impermeable rocks such as granite (Section 4.4). Water hardness is a traditional measure of the ability of water to react with soap to produce a lather, and for most consumers the problems associated with washing, and also the scaling of pipes and household appliances that use water, are the two major factors of concern.

An alternative measure of hardness is total dissolved solids (TDS), which is a measure of the total concentration of ions in water. The TDS in groundwater is often an order of magnitude higher than in surface waters. In aquifers the TDS increases with depth due to less fresh recharge water to dilute existing groundwater and the longer period for ions to be dissolved. The older and deeper the groundwater the more mineral rich the water becomes resulting in quite saline water. High concentrations of salts in groundwaters are often due to over-abstraction or to drought conditions when old saline groundwaters may enter boreholes through upward replacement, or due to saline intrusion into the aquifer from the sea. In Europe conductivity is used as a replacement for TDS measurement and is widely used to measure the degree of mineralization of groundwaters (Table 4.5).

Chemistry of hardness

Hardness is caused by metal cations such as calcium (Ca2+), but in fact all divalent cations cause hardness (Table 10.1). They react with certain anions such as carbonate or sulphate to form a precipitate. Monovalent cations such as sodium (Na+) do not affect hardness. Strontium, ferrous iron (Fe2+) and manganese are usually such minor components of hardness that they are generally ignored, with the total hardness taken to be the sum of the calcium and magnesium concentrations.

Introduction

There are three different groups of micro-organisms that can be transmitted via drinking water: protozoa, viruses and bacteria (Section 3.2) (Table 13.1). They are all transmitted by the faecal-oral route and so largely arise either directly or indirectly by contamination of water resources by sewage or, increasingly, animal wastes. It is theoretically possible, but unlikely, that other pathogenic organisms such as nematodes (roundworm and hookworm) and cestodes (tapeworm) may also be transmitted via drinking water (Gray, 2004).

Protozoa

There are two protozoa frequently found in drinking water that are known to be responsible for outbreaks of disease (Table 13.1). These are Cryptosporidium and Giardia lamblia.

13.2.1 Cryptosporidium

This parasitic protozoan is widely distributed in nature, infecting a wide range of animal hosts including pets and farm animals. However, it was only relatively recently that it was found to be a human pathogen as well. The first recorded case of human infection occurred as recently as 1976. The problem is that the protozoa form protective stages known as oocysts that allow them to survive for long periods in water while waiting to be ingested by a host. They are also able to complete their life cycle in just a single host as well as having an autoinfection capacity (Fayer and Ungar, 1986). Once infected the host is a lifetime carrier and is subject to relapses. In normal patients the protozoa give rise to a self-limiting gastroenteritis that lasts for up to two weeks, with children more at risk than adults. If the patient is immunosuppressed, infection will be life threatening. For example, it is a major cause of death among patients with AIDS (acquired immune deficiency syndrome). Two peaks in the number of infections are seen each year, one in the spring and another in the autumn.

The oocysts of Cryptosporidium are only 4–7μm in diameter and so are difficult to remove from raw waters by conventional treatment.

Micro-organisms in plumbing systems

We have seen that the contamination of drinking water by pathogenic and non-pathogenic micro-organisms occurs mainly at source (Chapter 13), although contamination can also occur during treatment or within the distribution systems (Chapters 19 and 25). The contamination of otherwise potable water can also occur within the consumer's premises. This is generally due to the type of plumbing system installed, a lack of basic maintenance and the careless use of appliances.

The householder is responsible for the maintenance and repair of the supply pipe, which runs from the water supply company's connection pipe at the boundary stop-tap to the house. All the water entering the house passes through this pipe so any fracture will allow possible contamination to enter. Sewerage pipes should be located well away from the supply pipe, preferably on the other side of the building.

Back-syphonage in plumbing systems is more of a problem in older buildings as modern building regulations and water byelaws incorporate measures to prevent it. It generally occurs when a rising main supplying more than one floor suffers a loss of pressure at a low point in the system, causing a partial vacuum in the rising main. Atmospheric pressure on the surface of, for example, a bath full of water on an upper floor in which a hose extension or a shower attachment from an open tap has been left, will push the contents of the bath back up through the hose and tap into the plumbing system to fill the partial vacuum. Plumbing systems suffer from constant changes in pressure, so care should always be taken when hoses are left to run water into containers. Farmers, who often need to fill large pesticide sprayers with water, need to take special care to ensure that the end of the hosepipe is never allowed to fall below the liquid surface in case of back- syphonage. This is extremely important if private supplies are pumped by a submersible pumping system from an underground storage tank.

Introduction

Water supplies are uniquely vulnerable to terrorism, whether it is aimed at humans, livestock or crops. Access to water supplies, and treated water, via service reservoirs and the distribution network places water at particular risk (Denileon, 2001). The key actions that can be taken against supplies are (1) physical damage to water treatment and distribution systems, or the computer systems used to operate them, interrupting the supplies or preventing adequate treatment; (2) deliberate chemical contamination; and (3) bioterrorism using either micro-organisms or biotoxins.

Chemical contaminants are not very effective due to the volume of chemical required and the relative toxicity of most chemicals. In contrast, biological agents have been widely developed for warfare but rarely employed (Hawley and Eitzen, 2001). Although most are airborne many of these organisms and toxins are equally effective via water. The infective dose of the disease agent varies significantly as does the effect on the target organism or population. Microbial agents are infectious, in some cases can be subsequently spread from person to person or via contaminated food, are stable within the environment, colourless and odourless, and have delayed response times unlike chemical contaminants that cause an effect in the target organism relatively quickly.

Biological agents are classed into two categories by the US Center for Disease Control and Prevention (Rotz et al., 2002). Category A micro-organisms posing the highest risk with high morbidity and mortality rates include smallpox, anthrax, plague and botulism, while category B agents pose a much lower risk and rates of mortality and morbidity such as brucellosis, typhus fever and cholera. There is a third group, category C, for emerging biological agents such as hantaviruses and tickborne haemorrhagic fever viruses. A wide range of bacteria, fungi and algae produce toxins, mostly potent neurotoxins, posing a particular risk to water supplies. These include a flatoxins, botulinum toxins, microcystins, ricin and saxitoxin (Section 11.2).

Water treatment and disinfection are the front-line protection for targeted water supplies and most treatment plants employ continuous pollutant and/or toxicity detectors in some form.

Aluminium

Aluminium is a widespread and abundant element that is found as a normal constituent of all soils, plant and animal tissue. It is especially common in food, resulting in a typical daily intake of between 5 and 20 mg depending on individual variations in eating and drinking habits. In the UK the mean dietary aluminium intake is approximated at 3.9 mg d−1 (Ysart et al., 2000) (Table 15.1). It is recommended that the dietary intake should not exceed 6 mg d−1 if potential toxicity problems are to be avoided (Soliman and Zikovsky, 1999). Diet is a major factor in aluminium uptake. For example, aluminium is taken up in large amounts by tea plants, so that drinking tea significantly enhances aluminium uptake (Flaten and Ødegård, 1988). In fact, tea may contain anything from 20 to 200 times more aluminium than the water it is made with. Aluminium can also be leached from cooking utensils (Jagannatha and Valeswara, 1995), and cooking acidic foods such as citric fruits, rhubarb or tomatoes can lead to enhanced leaching from aluminium pots and pans. Enhanced leaching has also been reported for spinach and other green vegetables. Aluminium leaching also occurs from coffee percolators made from aluminium. In new percolators coffee contains on average 4.1 mg Al 1−1, of which 85% comes from aluminium leached from the metal pot. This reduces as the percolator ages, although more than 70% of the aluminium in the coffee will still be leached from the pot. Elevated aluminium concentrations have also been noted in soft drinks (pH < 3.0) when supplied in aluminium cans (Table 15.2) (López et al., 2002). While aluminium packaging materials are normally coated with lacquers to reduce leaching, aluminium cartons and packaging can contribute to the amount of aluminium in the diet. It is difficult to estimate the exposure to aluminium from containers and cooking utensils, and in most cases they are likely to be small compared with the total dietary intake.

Source of odour and taste problems

Most odour and taste problems occur at the water treatment stage and are linked to chlorination (Levi and Jestin, 1988). Chlorine itself has a distinctive odour with a reported taste threshold of 0.16 mg 1− at pH 7 and 0.45 mg 1− at pH 9. Although consumers generally accept a slight chlorine odour as a sign that the water is microbially safe, excessive concentrations of chlorine can make the water most objectionable. In recent years a number of outbreaks of diarrhoeal diseases have occurred when water companies have reduced the level of disinfection due to complaints of chlorinous odours. Clearly a balance must be struck between the protection of public health and wholesomeness in terms of taste and odour. This is an operational problem which can be solved in a number of ways, such as using more sensitive disinfection equipment at the treatment plant, disinfecting within the supply zone or distribution network or by using alternative disinfectants.

Ammonia reacts with chlorine to produce three chloramines (monochloramine, dichloramine and trichloramine or nitrogen trichloride). These compounds are more odorous than free chlorine and become progressively more offensive with increasing numbers of chlorine atoms, with trichloramine by far the worse. The proportion of each compound formed depends on the relative proportions of chlorine and ammonia present, the chlorine demand exerted by other substances and the pH (Montgomery, 1975). This is usually avoided by using breakpoint chlorination in which a high chlorine to ammonia ratio is used (i.e. > 7.6:1 at pH 7–8) so that the residual chlorine present is mainly in the free form (Section 14.2). It is not only ammonia that reacts in this way to produce odorous compounds, although the reactions are considerably slower and continue within the distribution system (Section 21.1).

Phenolic compounds have already been mentioned in Chapter 8. They produce odorous compounds during chlorination. Phenol itself has very little odour, but its chlorinated forms monochlorophenol and dichlorophenol have an intense odour and are difficult to remove by subsequent treatment.