Hint. It’s not about nature. It’s about us.

People live in environments created by nature, yet modified by human activity. In turn, some of these modifications imperil our own health. Environmental Health is the section of public health that addresses the impacts that people and our production have on our health.

Yet, this science is complex and difficult. Each person is unique. What causes illness in one may have no significant impact on others. New and diverse “vectors” are steadily added to the environment by human and corporate activity all over the world, yet most are unregistered, unreported and, in the eyes of their purveyors, benign, not in need of monitoring. Once in the environment, they can interact with other factors, complicating issues of cause and effect. This ever-changing mix makes environmental health trends difficult to discern…and, once identified, difficult to accept and address. In a word, environmental health concerns are often controversial.

Consider the recent flair-up over Kevin Drum’s piece in Mother Jones: America’s Real Criminal Element: Lead. Drum presents a compelling case that leaded gasoline was the cause of America’s last crime wave. It provoked considerable reaction.

Gasoline Additive Stokes Crime?

In recent years (since 1995), violent crime in the U.S. has declined from its all-time high to its lowest level in more than 40 years. While both sides of the political spectrum claim credit, the change baffles criminology experts. Among the reasons proffered are increased use of psychotropic drugs, legalization of abortion in the 1970s, wider use of video games and social media, an aging population, improved policing strategies and more incarceration.

Drum came up with another reason, and it may be the best of all: lead.

Laborers are familiar with lead (Pb). It was once commonly used in paint, and is known to cause developmental disorders in children. The EPA has strict rules that govern its removal from old buildings and bridges.

In the 1920s, lead was first added to gasoline to eliminate the “pinging” in the higher compression engines then developing in the automobile industry. Thereafter, between 1925 and today, sales and use of automobiles in the U.S. rose from 17 million to 247 million, and the construction of the interstate highway system after 1955 forever concentrated their fumes in specific locations, often near city neighborhoods with large numbers of families and children. With the switch to catalytic converters (to control pollution) in virtually all cars made after 1975, lead – incompatible with converters – was weaned from the nation’s gasoline supply. Through 1995, due to wider, but uneven adoption of anti-lead restrictions in various states, its use steadily declined, reaching just 0.6% of sales before it was banned nationwide in 1996. Other nations also banned lead additives, though not at the same time as the U.S., thus creating useful comparisons of their crime rates with the dates of their banishments.

Drawing on investigations of this data by others, Drum found that with a lag time of 23 years, lead emissions from vehicles explain 90 percent of all variation in U.S. violent crimes (see graphic). His theory is confirmed by the data from other nations.

Last month’s publication of Drum’s work intrigued scientific readers, but it also brought out some skeptics, one of whom insists that the whole matter is just too complex for rational assessment. Drum’s response and the online commentary is edifying, and interested readers may draw their own conclusions.

Nevertheless, the whole presentation provides a useful exposition of “environmental health” and its great dilemmas: What do we know? Do wereally know it? Given its uncertain nature, what do we do with the knowledge we have? Further, with so many environmental health hazards now global in impact, how and by what entities are they to be addressed? Usually, these questions are not easily answered.

What to do?

One problem in perfecting environmental health science is narrow interests. For the most part, scientific research is directed by corporations, governments or other entities with a large stake in the status quo. While some discoveries can be profitable, many might curtail profit or power if they were widely adopted. Potentially unprofitable research is sometimes suppressed, and inevitably, fresh insights must struggle for attention and acceptance against entrenched interests and beliefs.

Moreover, since each of us generally enjoys benefits from the activities in which we already engage, we are often reluctant to change them, even if we hear of problems. Inertia rules. Though revamping personal habits is fundamental to any society-wide transformation, building momentum for social change and reaching critical mass is difficult.

Climate Change

Perhaps, the best known and most controversial environmental health issue of all is climate change, made famous in Davis Guggenheim’s 2006 documentary An Inconvenient Truth featuring Al Gore. The movie advances the theory that burning fossil fuels are releasing so much carbon dioxide into the atmosphere that the planet is warming, threatening the future of civilization. Dating back to the 1980s, Gore long championed the cause, but all along, it was doubted and derided by others. Now, after years of record high temperatures, widening droughts, intense storms and devastating wildfires, Hurricane Sandy’s election eve assault on the Northeast appears to be the straw that broke the camel’s back. A consensus for action on climate change seems to have jelled, and President Obama is calling on the nation to tackle the problem.

Action Ahead?

It remains to be seen whether the U.S. and the world can take adequate action soon enough to prevent catastrophic global warming. But, environmental health is undergoing a renaissance, gaining coherency and public acceptance unseen since the 1970s. We are likely to see greater attention to these difficult but vital concerns in the years to come.

To educate yourself, check out these resources:

World Health Organization (Environmental Health)

American Public Health Association (Environmental Public Health)

CDC National Center for Environmental Health

Health Canada

[Steve Clark]