TOXICOLOGICAL
CHEMISTRYAND  
BIOCHEMISTRY
THIRD EDITION

In order to understand toxicological chemistry, it is necessary to have some understanding of the environmental context in which toxicological chemical phenomena occur. This in turn requiresan understanding of the broader picture of environmental science and environmental chemistry,which are addressed in this chapter. Also needed is an understanding of how environmentalchemicals interact with organisms and their ecosystems, as addressed by the topic of ecotoxicology.

Environmental science can be defined as the study of the earth, air, water, and living environments, and the effects of technology thereon.1 To a significant degree, environmental science hasevolved from investigations of the ways by which, and places in which, living organisms carry outtheir life cycles. This is the discipline of natural history, which in recent times has evolved intoecology, the study of environmental factors that affect organisms and how organisms interact withthese factors and with each other.

TAR SANDS

Alberta’s tar sands (also known as oil sands) are the world’s third-largest reserves of recoverable crude oil.60 Though it is expensive to extract, this oil fetches a much lower price than other heavy oils due to the difculty in getting the landlocked tar sands to the United States and other potential markets. Thus, tar sands companies are desperate to promote new and expanded pipelines. The need for new pipeline capacity is particularly acute as companies ramp up production at projects that were started several years ago, while still planning new projects, such as Teck Resources’ massive Frontier Mine.

CASE STUDY: OPPOSING THE LINE 3 TAR SANDS PIPELINE

Enbridge’s Line 3 so-called “replacement” project is a proposal for a new pipeline that would cover more than 1,000 miles from Hardisty, Alberta, to Superior, Wisconsin, transporting an average of 760,000 barrels of crude oil from the Alberta tarsands each day, with capacity for 844,000 barrels per day.

Enbridge intends to abandon its existing Line 3 pipeline if it is able to complete its new Line 3, leaving the corroding pipe in the ground and a lasting legacy of contamination. The replacement Line 3 would take a brand new route. This path cuts through pristine wetlands and watersheds in northern Minnesota, passing through the headwaters of the Mississippi River to the shores of Lake Superior, through the heart of Minnesota’s lake country and some of the largest and most productive wild rice beds in the world.

CASE STUDY: EXTREME ENERGY INJUSTICE AND INDIGENOUS RIGHTS VIOLATIONS IN ALASKA

Alaska Native rights and Indigenous sovereignty cannot be separated from the problem of extreme oil and gas production in Alaska. Politicians and oil interests have a long history of pushing legislation nullifying Alaska Native land claims, especially those claims that stood in the way of oil and pipeline development.

After being declared a state in 1958, Alaska selected for oil development tracts of land on the North Slope, in an area called Prudhoe Bay. Without consultation and consent of the local Inupiat village, but with approval of the U.S. Bureau of Land Management, these lands were transferred to the state.

COAL MINING POLICY REVIEW

The global coal mining sector is under pressure like never before. An increasing number of analysts and industry watchers (including at Goldman Sachs175) are declaring that thermal coal has now entered structural, rather than cyclical, decline. Coal mining companies have to contend with the fact that six countries, states, provinces, or cities have completely phased out coal power since 2014, and an additional 17 haveannounced a coal power phase-out date of 2030 or sooner. Among them are three G7 countries, eight EU countries, and Beijing and Delhi — all committed to becoming coal-free. Also in 2017, South Korea, the world’s fourth largest coal importer, announced a major reduction in its coal power reliance, a move that has dire implications for Indonesian coal producers in particular.

CASE STUDY: HOUSTON: HURT BY THE CAUSES AND SYMPTOMS OF CLIMATE CHANGE

The torrential downpours and violent winds of Hurricane Harvey struck Houston, Texas in August and September 2017. Harvey killed at least 68 people and displaced over one million,leaving approximately 200,000 damaged homes along its 300- mile trail. Damages from the hurricane tallied an estimated $125 billion. The aftermath is still being felt through the region.

Environmental racism exacerbates the pain caused by natural disasters by disproportionately affecting low-income communities of color close to industrial sites. In the wake of Harvey, these communities were exposed to increased levels of toxic chemicals from Houston’s superfund sites, chemical plants, and oil refneries during the storms. Houston is an industrial hub with a busy ship channel, in a state that’s home to 30 percent of the country’s oil refning capacity. According to the Environmental Defense Fund, Hurricane Harvey causeddamaged refneries and chemical facilities to release nearly sixmillion pounds of cancer-causing chemicals into the air.

STOP FUNDING FOSSILS: WHY THE FINANCE SECTOR MUST FOLLOW THE WORLD BANK’S LEAD

            Achieving the goals of the Paris Climate Agreement will require action across all sectors of the economy, and the finance sector is clearly fundamental. In fact, one of the Paris Agreement’s three objectives is “making finance flows consistent with a pathway towards low greenhouse gas emissions and climate-resilient development. Recent announcements by some of the world’s largest financial institutions reveal an emerging consensus that all fossil fuel investment and financing risks both climate security and economic value. The finance sector has an important role to play in ending further exploration and the expansion of fossil fuel production.

THE BEGINNING OF THE END

2017 may go down in history as the year when it frst became clear that the fossil fuel era was fnally starting to sputter to an end. The cost of new solar and wind power started to fall below the price of new coal and gas plants in a growing number of regions. The CEO of NextEra Energy, one of the largest electricity producers in the US, now predicts that “early in the next decade” — just a few years from now — power will be cheaper from unsubsidized new wind and solar plants in the US than from existing coal and nuclear plants. It’s still far from game over for the fossil fuel industry, but the game hasdrastically changed.

TASTE—IT’S THE STRUCTURE THAT COUNTS

Why do certain substances taste sweet, sour, bitter, or salty? Of course, it has to do with the taste buds on our tongues. But how do these taste buds work? For example, why does sugar taste sweet to us? The answer to this question remains elusive, but it does seem clear that sweet taste depends on how certain molecules fit the “sweet receptors” in our taste buds.

PROTECTING THE OZONE

Chlorofluorocarbons (CFCs) are ideal compounds for refrigerators and air conditioners because they are nontoxic and noncorrosive. However, the chemical inertness of these substances, once thought to be their major virtue, turns out to be their fatal flaw. When these compounds leak into the atmosphere, as they inevitably do, they are so unreactive they persist there for decades. Eventually these CFCs reach altitudes where ultraviolet light causes them to decompose, producing chlorine atoms that promote the destruction of the ozone in the stratosphere (see discussion above). Because of this problem, the world’s industrialized nations have signed an agreement (called the Montreal Protocol) that banned CFCs in 1996 (with a 10-year grace period for developing nations). So we must find substitutes for the CFCs—and fast.