Chapter 72: Water Pollution

INTRODUCTION

On July 28, 2010, the United Nations General Assembly adopted a resolution recognizing: “the right to safe and clean drinking water and sanitation as a human right that is essential for the full enjoyment of human life and all human rights.”¹ Despite this international commitment, as of 2015 2.1 billion people lacked access to safe drinking water and 4.5 billion lacked access to safely managed sanitation worldwide.² An estimated 1.8 million deaths resulted from diseases related to water pollution in 2015, disproportionately affecting children under 5 years of age in lower-income countries.³ Many of these deaths are preventable through access to safe and clean water for drinking and hygiene.⁴ Although in most upper-income countries advances in drinking water and wastewater treatment over the past century have reduced the threat of diarrheal waterborne disease, new threats to the integrity and safety of water resources have emerged including treatment-resistant waterborne pathogens, persistent industrial and agricultural chemicals, a changing climate, and an aging water treatment and distribution infrastructure.

This chapter will discuss the main drivers and public health aspects of water pollution that result in human illness and mortality. The focus will be on diseases and other adverse health effects resulting from exposures via ingestion, inhalation, or absorption of water contaminated by pathogenic microorganisms (bacteria, viruses, protozoa) and chemicals. Vector-borne diseases associated with insect hosts, which may breed in water such as malaria, dengue, Zika, and yellow fever, will not be emphasized, nor will the ecological effects of water pollution or potential health effects resulting from exposures at treated water venues (pools, hot tubs, spas).

HISTORICAL PERSPECTIVE

Miasma Theory of Disease

Contaminated water has only been recognized as a cause of disease and illness for a little over 150 years. Before the mid-1800s, the “miasma” theory of disease prevailed which posited that bad air, unhealthy vapors and poisonous emanations from rotting carcasses or vegetation were responsible for most diseases and illnesses.⁵ The miasma theory was first attributed to the Greek physician Hippocrates from the fourth or fifth century BCE,⁵ and was used to explain many important diseases over the centuries including tuberculosis, plague, malaria, and cholera.⁵ Miasma theory remained the prevalent disease theory for much of the nineteenth century.⁶

Ancient Sanskrit and Greek records indicate that treatments such as exposure to sunlight, filtering through charcoal and straining were used to improve water taste and clarity as early as 4000 BC. Alum was used in Egypt in 1500 BC to induce coagulation and help clarify water.⁷ Aqueducts, established in ancient Rome and Assyria, helped to keep waste water separate from water used for drinking and bathing. Because water was not considered an important disease transmission route, these early water treatments were focused primarily on the aesthetic (clarity, taste, odor) qualities of water and not on disease prevention.