The discovery and persistence of regions of ozone depletion over large areas of the earth's surface (the ‘ozone hole’) has fuelled a significant increase in interest about UV radiation (UVR). This interest ranges from investigations focused on atmospheric interactions and the physics of light transmission (WMO, 1988, 1989, 1991, 1995, 1999; UNEP, 1992) to photobiological effects and agricultural, economic and social impacts (UNEP, 1991, 1994, 1998). The purpose of this chapter is to present some background information about the solar spectrum and introduce a few of the fundamental physical concepts related to UV in the atmosphere (Section 2.1) and underwater (Section 2.2).

Unless other sources are mentioned, the modelled irradiances at the earth's surface used in Section 2.1 were calculated with a two-stream radiative transfer model (Frederick & Lubin, 1988), the values of measured irradiance were provided by the National Science Foundation (NSF) Radiation Monitoring Program (Booth, 1990–1997), and the values of total column ozone by Nimbus 7/Meteor 3, Total Ozone Mapping Spectrometer (TOMS) data (McPeters, 1994).

Atmospheric UV radiation

Extraterrestrial solar radiation encompasses a wide region of the electromagnetic spectrum and exhibits a distribution similar to the emission of a black body at a temperature of 5800 K (Koller, 1965; Madronich, 1993). Fortunately, for the purposes of this chapter, only a portion of the solar spectrum needs to be considered. The visible portion of the total solar radiation spectrum covers a region of the spectrum from 400 to 700 nm. Wavelengths from 10 to 400 nm correspond to the UV region and wavelengths higher than 700 nm correspond to the infrared region.

Introduction

Most research examining the effects of UV radiation (UVR) on marine microbial communities has been directed at phytoplankton and primary production. It is now apparent, however, that other microbial trophic levels must also be considered when one is investigating the ecological impact of UVR. The importance of bacterioplankton in oceanic processes has become widely recognised. Bacteria have been found to account for up to 90% of the cellular DNA in oceanic environments (Paul & Carlson, 1984; Paul, Jeffrey & Deflaun, 1985; Coffin et al., 1990) and the role of bacteria in elemental and nutrient cycling has received extensive study (Falkowski & Woodham, 1992). Bacteria have been found to play a vital role in carbon cycling, providing significant amounts of material to higher trophic levels. Various studies have shown that bacteria consume a significant proportion of primary production, although the data are quite variable and depend on location and season (Fuhrman & Azam, 1980; Hansen et al., 1983; Cota et al., 1990; Sullivan et al., 1990).

Viruses are ubiquitous and abundant in marine environments infecting bacteria, phytoplankton and heterotrophic flagellates (for reviews, see Børsheim, 1993; Fuhrman & Suttle, 1993; Bratbak, Thingstad & Heldal, 1994). While viruses are often considered to be pathogens of mammals or higher plants, it has become apparent that the 108 to 1011 viruses 1−1 that are found in marine surface waters, mostly infect marine bacteria and phytoplankton (Suttle, Chan & Cottrell, 1990; Fuhrman & Suttle, 1993).

Introduction

Solar radiation initiates a wide variety of photochemical transformations in natural waters, ranging from primary photolyses involving well-defined chromophores to complicated photoreactions involving ill-defined chromophores, such as humic substances.The broad spectrum of photochemical transformations that have been documented attest to the importance of photochemistry in aquatic biogeochemical cycles (Zafiriou, 1977; Zika, 1981; Larson & Berenbaum, 1988; Cooper et al., 1989; Hoigné et al., 1989; Blough & Zepp, 1990; Helz, Zepp & Crosby, 1994; Zepp, Callaghan & Erickson, 1995;Blough, 1997; Moran & Zepp, 1997). These transformations are driven largely by the absorption of light by dissolved organic matter (DOM), principally in the ultraviolet (UV) region of the solar spectrum (λ < 400 nm).

Currently, it is not possible to assess quantitatively the effects of various photochemical processes on plankton in marine and freshwater environments. A comprehensive understanding of the nature of photochemical–biological interactions in aquatic systems is lacking, at both the cellular and the ecosystems levels. There is evidence for short term deleterious effects of UV radiation including DNA damage (Karentz, Cleaver & Mitchell, 1991), inhibition of photosynthesis (Cullen, Neale & Lesser, 1992; Smith et al., 1992) and decreased nutrient uptake (Döhler et al., 1991). It is also clear that organisms have mechanisms to repair damage and screen incident UV radiation (Vincent & Roy, 1993; Karentz, 1994; and see Chapter 8). As may be expected, there is considerable interspecies sensitivity to short and long term exposure to UV radiation that may lead to changes in the community structure favouring UV-resilient species (Calkins & Thordardøttir, 1980; Worrest, Thomson & Van Dyke, 1981; Worrest, 1983). However, some of the changes that are observed are counter-intuitive and make sense only through examination of trophic level interactions.

Introduction

In a seminal paper, Lancaster (1966) suggested a new approach to consumer theory. His suggestion was based on the idea that the satisfaction derived from the consumption of a good is not due to the good per se, but rather from the characteristics of the good. The hedonic analysis was developed further by, for example, Rosen (1974) and has been employed extensively for various purposes. For example, a hedonic method for estimating people's willingness to pay for a change in the provision of environmental quality characteristics has been used (with varying degrees of success) in environmental economics since the end of the 1960s. The importance of product characteristics for consumers' enjoyment was, however, acknowledged within economic research at an early stage. In an example concerned with automobiles, Court (1939) constructed price indexes that accounted for quality change by following a procedure which he called the hedonic pricing method. A crucial part of the method was the identification of measureable characteristics that relate to automobile quality.

It is interesting to note that a focus on characteristics may offer a procedure to predict the use of new products. Roughly speaking, it may be possible to describe a product which is not yet introduced into the market as a new combination of characteristics that describe already existing products. This possibility is not fruitful for some groups of products. For example, one important reason for buying a mug is probably its look, maybe the presence of a text or a picture on the mug. One or several ‘look characteristics’ that are likely to be related to people's purchase decisions are in such a case not easy to define or to measure.

Introduction

This chapter is a follow up to a previous paper in which a first attempt was made to address some of the institutional aspects of the European Commission Directive on drinking water. Whereas the previous paper, after a short theoretical introduction, focused mainly on the legal history of the Directive and its implementation in Italy, this chapter is devoted to the more theoretical question of what legal instruments can be used to avoid an accumulation of pesticides in drinking water. The current situation with drinking water is that the EU is using Directives to set strict quality standards to protect drinking-water supplies. Once these EU standards are set, the Member States have to implement them in their national systems. It has been shown that the current regulatory approach for pesticides is not functioning satisfactorily. The research by the ecotoxicology group has demonstrated that the current Italian approach of a ban on one pesticide (i.e. atrazine) is inefficient since it does not prevent an accumulation in drinking water of other pesticides. Moreover, the research has shown that the real problem with pesticides is not their toxicity, but more importantly the accumulation of potentially toxic elements in drinking water. The current regulatory approach gives the wrong incentives to pesticide manufacturers and to the users of the pesticides, the farmers. It does not lead to a reduction of toxic pesticide accumulation in drinking water.

Introduction

This chapter examines the reasons why private decision-making on the part of agricultural chemical manufacturers might lead to products with socially undesirable characteristics being sold in socially inefficient quantities. The source of the problem is market failure: some significant economic factor goes ‘unpriced’, so that economic activity is undertaken without consideration of its full impact. Two market failures will be considered. The first is the presence of externalities (both the standard story of a damage externality, in which agents considered only the private, and not social, costs of their actions; and a ‘surplus externality’, arising because profit-maximising firms consider only the marginal consumer, instead of all consumers, in their production decisions). The second is imperfect competition – the effect of the structure of the agriculture chemical manufacturing industry (a small number of large multinationals competing in the same product market) on producer's choices of chemical characteristics.

Externalities

An externality arises when the decisions of some economic agents (individuals, firms, governments) – whether in production, in consumption, or in exchange – affect other economic agents, and are not included in the priced system of commodities, i.e. they are not compensated. An alternative way of expressing this problem is to say that property rights are not assigned appropriately, so that the incidence of effect does not coincide with the distribution of legally recognised controls. A third equivalent statement is that economic agents consider only their private marginal costs when making decisions; they do not consider the total, or social (marginal), costs of their actions. It is the gap between private and social marginal costs that gives rise to the externality.

Introduction

The potential harmfulness of a chemical in the environment depends on several major properties: toxicity to organisms, bioaccumulation in tissues, persistence, mobility and distribution patterns in environmental compartments. Historically, the focus of ecotoxicology was on the first property, toxicity, and techniques were devised to enable maximum concentrations of no harmful effect to be established, usually using responses measured in whole organisms. These concentrations then formed the basis of environmental quality standards.

For many years, these studies played a vital role in the control of the major causes of chemical pollution from industry. However, in the past three decades, there has been an increasing awareness of the special importance of persistent chemicals, which can be transported and detected far from their original source; this problem was highlighted by the discovery of widespread environmental contamination by DDT and later by polychlorinated biphenyls (PCBs). Organisms over a wide area could be exposed to low concentrations of such substances for a long period of time. Ecotoxicologists then began to search for very sensitive biological responses in order to detect the effect, if any, of these low concentrations.

Considerable attention was focused on organismal effects at the cellular or subcellular level, where they first become apparent. These were often found at exposure concentrations lower than those predicted to be safe from tests on whole organisms. The ensuing scientific and political debate served only to cloud the validity of existing environmental quality standards, and indeed shed doubt on the value of ecotoxicological data in pollution prevention and control.

At the same time, the definition of pollution was changing.

Moving towards a preventive approach

Toxicology and ecotoxicology are disciplines that have developed in response to a need for information about the possible damages that might result from chemical usage. During the seventies a shift occurred from a posteriori control of chemical impacts to the prevention of this type of damage. The change in emphasis occurred first in the scientific community and then in the administrative and political spheres. As a result, many important regulations were approved for application across Europe. The essence of these regulations was to require preliminary information on the toxicology and ecotoxicology of chemicals in order to make available data needed for a preventive risk assessment of the characteristics of the marketed chemicals.

In particular, the Toxic Substances Control Act (US EPA, 1978) in the USA and the Sixth Amendment to the Directive on Dangerous Substances (EEC Council Directive, 1979) in Europe require the development of a basic set of information before a new chemical substance may be marketed. The required data set dealt with several characteristics of the substance (chemical structure, use patterns, physico-chemical properties, analytical methods, etc.) and includes toxicological and ecotoxicological tests at different levels of complexity in relation to the amount of the substance produced and the results at the preliminary levels (see Table 1).

The challenge to the scientific community was therefore: to what extent can the impacts of the chemicals be predicted by reference to this relatively limited set of data?

The problem under consideration

In July 1980 the European Commission issued a Directive on drinking-water quality (80/778/EEC) setting a maximum admissible concentration for 71 distinct parameters. One of the most strictly regulated substances in the directive was the set of chemical pesticides. The European Commission adopted a ‘practically zero’ level of permissible contamination for these substances. The limit for any individual pesticide product was set at the trace level of 0.1 μg/l; a ‘cocktail’ standard for the allowed aggregate level of contamination by all chemical pesticides was set at 0.5 μg/l. These were levels of chemical contamination that were only just detectable under then-existing monitoring technologies. The Commission's standard was intended as a clear and unequivocal pronouncment against the accumulation of chemicals within the drinking water of the EEC.

Despite this pronouncement against chemical accumulation, pesticides have been accumulating in groundwater over the past 15 years to such an extent that several substances have breached the allowed concentration in groundwater in many of the agricultural districts across the European Union (EU) (see, generally, Bergman and Pugh, 1994). This is important because two-thirds of the EU citizenry continue to acquire their drinking-water supplies from untreated groundwater, i.e. directly from the aquifers underlying their communities. In adopting its tough stance against chemical accumulation, it had been the object of the European Commission to stimulate a comprehensive strategy of pesticide management (based on agricultural, land use and pesticide management). However, the continued accumulation of pesticides in European groundwater supplies placed the EU in the position of choosing between two poor options: either the relaxation of its earlier drinking-water quality directive or the costly treatment of groundwater prior to delivery to consumers.

Introduction

Some persistence is a desirable characteristic of useful chemical products, since otherwise the chemical would degrade instantaneously into inert components of little usefulness. The objective of any purchaser of a chemical product is to acquire the activity of the product. The more persistent the product, the less often the purchaser must expend the labour and capital required to apply it. For these reasons chemical persistence is not an unmitigated ‘bad’; it is in fact an in-built characteristic driven by the demands of consumer groups.

However, the socially optimal degree of persistence is not necessarily ensured through market mechanisms, since persistence redounds to the benefit or detriment of many individuals other than the purchaser. Specifically, since chemicals that are persistent must be active within one of the various basic environmental media (atmospheric, hydrological or organic), this activity will also be experienced by the many others in contact with the same medium. Since this activity may be undesirable from the perspective of the many other persons subjected to it, they might prefer a lower level of persistence than would the individual who is making the purchase decision without taking their preferences into account. It is the internalisation of this externality that is the subject of this chapter. Policies must be designed in order to mitigate the problem of greater-than-optimal product durability when persistence ensures that people other than the consumer will feel the impacts of the product. The particular policies that we investigate here are those that will cause manufacturers and users to take the correct decisions in the design and application of agricultural pesticides.