Not so fertile lands

Generations at Risk
March 31, 2000

The stated aim of the authors is to write a book that could be easily understood by the general public but that would also be a resource for medics, public-health specialists, community activists, policy-makers and industrialists. This audience encompasses a wide range of expertise and aspirations. Nevertheless the authors have succeeded admirably.

The entire book is interesting and well written, and great care has been taken in explaining technical terms. For instance, the descriptions of statistical significance and statistical power are excellent, as are the descriptions of reference dose and Noael (no observable adverse effect level). For general readers who wish to know more about the potential toxins in the environment, the book provides all the basic facts and figures. If they wish to delve more deeply or become involved in local (United States) environmental assessments, the book also provides guidance. For the practising medic and public-health specialist, the book will provide a sound foundation, detailing the range and type of impact that the environment can have on reproductive health. It also whets the appetite for more knowledge. The book is thoroughly and extensively referenced, which will speed up the quest for further knowledge, although because the referencing is not always fact specific, readers may sometimes be disappointed that a reference for a particular fact is not immediately apparent. The book will also inform policy-makers and industrialists of the dangers of exposure and provide them with objective knowledge about the potential consequences. This should allow policy-makers to build in appropriate safety procedures and industrialists to operate at the highest level of responsibility. For those based in the US, the book provides a good overview of the regulatory authorities and their specific roles and responsibilities.

To target a book at the community activist seems a curious ambition, but this possibly depends on how one characterises a community activist. The authors have taken care to present both sides of arguments and to interpret evidence objectively. Their book should provide anyone who is concerned about a potential reproductive hazard in their environment to obtain the facts and to argue their point.

Generations at Risk is divided into three parts. The first describes the understanding and use of science. Chapter one covers the elements of reproductive and developmental physiology, and chapter two the role of science in public-health decision-making. The description of reproductive and developmental physiology is wonderfully lucid. Included are several figures that, for once, seem superfluous because of the excellence of the writing. The chapter on the role of science in public health is first class. In pages the authors manage to convey the basic tools of epidemiology and the scientific method. The final section on quantitative risk assessment would, however, have benefited from a worked example.

The second part covers reproductive and developmental effects of selected substances and human exposures. There are chapters on heavy metals, organic solvents, pesticides, endocrine disruptors and human exposures to reproductive toxicants. The choice of heavy metals appears somewhat eclectic, but there is evidence that they all affect reproductive health. The physiological and toxicological points of each metal are described and a helpful summary of the key points is included.

Organic solvents are dealt with in chapter four, which starts with a brief description of solvents and their impact on reproductive health and reviews some of the key research on the impact of solvents and on spontaneous abortions. A helpful table is included, which allows the reader to make a judgement on the likely quality of the research. It could have been improved had the authors followed their own advice and included the 95 per cent confidence intervals of the odds ratios. Nevertheless, they interpret the research carefully, and gently persuade the reader of the facts and the limitations. The chapter ends with a description of the profiles of 13 solvents: benzene, chloroform, epichlorohydrin, formaldehyde, glycol ethers, methylene chloride, N-methyl-2-pyrrolidone, perchloroethylene, phenol, styrene, toluene, trichloroethylene and xylene.

The next chapter is about pesticides and it follows a similar approach to that on solvents. Again, very helpful tables are included that summarise many of the important epidemiological studies. The section on pesticide profiles is limited to those that are used commonly and in high quantity. Substances are described under the group headings of: organophosphates and carbamates, organochlorines, pyrethrins and pyrethroids, fungicides, benzimidazole fungicides, herbicides, acaricide, and fumigants.

Chapter six is devoted to the endocrine disruptors - substances that mimic, block or hinder normal hormonal activity. Included is a clear and succinct description of the mode of action of hormones, which focuses attention on why endocrine disruptors should be taken seriously as health hazards. The authors report the literature with commendable objectivity. Profiles of the main endocrine disruptors are included. Comprehensive reviews are presented for dioxin and polychlorinated biphenyls, more truncated reviews for alkylphenols, bisphenol-A, phthalates, pesticides and phytoestrogens.

A focus on human exposure to reproductive toxicants concludes the second part. It starts with a discussion of the importance of accurate exposure assessment and describes the major problems with obtaining good exposure data. Some of the major sources of exposure data available in the United States are reviewed and there is a discussion of the relationship between exposure data and some of the chemicals described in the book. The authors focus their attention entirely on data available in the US, but readers from elsewhere can benefit from the general concepts. Finally, the exposure data available for some known and suspected reproductive toxicants is discussed.

The third part is a guide to investigating environmental threats to reproduction. Chapter eight discusses the regulation of hazardous chemicals in the US and the individual's right to know. The information will be helpful to researchers in the US, although the general concepts are likely to apply more widely. It will also probably appeal to the policy-maker and the industrialist, as it describes the major regulatory laws intended to protect the health of humans and of the environment. Assessing reproductive threats at home, in the community and in the workplace is the focus of chapter nine, which is something of a curate's egg. It includes some helpful pointers on sources of such toxins. Most importantly, it gives practical solutions on how to minimise risk. But in other sections it purports to show how to conduct research effectively - yet it seemingly ignores the sound epidemiological evidence presented earlier in the book.

The penultimate chapter is a primer for the clinician. The information given is sensible but appears rather trite and patronising. However, there is an excellent table included that details the biological monitoring appropriate for the major heavy metals, solvents and pesticides. The chapter ends with a short but comprehensive list of further reading.

The final chapter exhorts us to embrace the underlying philosophy of the book, namely that "a precautionary approach is essential to systematic protection of public health and the environment".

There are two appendices. The first provides an annotated list of names and addresses (including web addresses) of useful sources for information about hazards in the environment. As the authors admit, it is not inclusive. The second describes, in tabular format, the reproductive outcomes associated with the major solvents, heavy metals and pesticides.

With minor blemishes, this is a very good book. The reference list is pertinent and incredibly thorough. Throughout, the authors include, to great effect, helpful vignettes to underline the key concepts or to provide "real-life" examples.

Fiona Williams is lecturer in environmental epidemiology, Ninewells Hospital and Medical School, Dundee.

Generations at Risk: Reproductive Health and the Environment

Author - Ted Schettler, Gina Solomon, Maria Valenti and Annette Huddle
ISBN - 0 262 19413 9
Publisher - MIT Press
Price - £20.95
Pages - 417

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