One of the unintended consequences of the modern chemical revolution has been world-wide dispersal of contaminants. No ecosystem has been left untouched. No human has been born since the middle of the 20th century without some exposure, in the womb, to hormonally-active synthetic compounds. Much of the dispersal of the contaminants is by atmospheric or oceanic currents. (See OSF Chapter 6, To the ends of the earth, for a detailed description.) Even animal migrations play a role (see below).

The result is an uncontrolled, largely unmonitored experiment playing out at global scale. Several recent studies bring this home vividly.

All children sampled in a study of the presence of phthalate metabolites in urine contained at least 3 metabolites, with levels higher than those that had been reported in a study of phthalate urinary metabolites in adults. More...

Nonylphenols were discovered in the late 1980s to be estrogen mimics. Now a team of German scientists reports that nonylphenols are present in a wide variety of foods bought in German marketplaces, everything from gooseberry marmalade to liver sausage to chocolate crumble to doublecream cheese and baby foods. All samples exampled contained measurable amounts of nonylphenols. More...

PFOS--perfluorooctane sulfonate--has emerged as a new type of persistent, organic pollutant that binds to proteins rather than accumulating in fatty tissues. The widespread nature of PFOS contamination was missed for a long time, even though the compound has been in commercial use (in products like 3M's Scotchgard) since the 1950s. New studies are documenting PFOS contamination in many living organisms around the world, including people (pdf file), polar bears and bald eagles.

PBDEs are popping up all over. These are polybrominated flame retardants, used in many different types of plastics and plastic-containing products. They are powerful thyroid disruptors that are both persistent and bioaccumulative. It turns out that when they leach out of the plastics in which they are put, they quickly find their way into the biosphere. One prominent pathway is polyurethane foam. When it degrades, the most toxic form of PBDEs (penta-BDE) escapes. In the US, not only is there passive transport of PBDEs via water and air currents, but PBDEs are also actively transported and dispersed because they are a prominent contaminant in sewage sludge, which is sprayed onto farmers' fields. This is looney!! Since the 1970s, PBDEs have increased more than 50-fold in breast milk. More on PBDEs

16 October 2000. In early 2001 the US Centers for Disease Control will release results of the most ambitious effort ever undertaken to measure exposures of Americans to chemical contaminants. They're calling it the National Exposure Report Card. It will will tell scientists and the public how many Americans -- and which ones -- have unusually high levels of lead, pesticides and other undesirable substances in their blood. Tests on 5000 people will include measurements for 25 substances, including heavy metals such as lead, cadmium and mercury, tobacco products, organophosphate pesticides such as chlorpyrifos and malathion, phthalates, dioxins and PCBs. Tests will be repeated each year to track trends in the US population.

For a 2003 update of this report...

According to data released in July 2000, concentrations of PCB and PCB-related contaminants are up to 70x higher in Inuit residents of far northern Canada than in blood samples taken from southern Canada. More...

Schindler, DW. 2000. Trends in usage and global redistribution of pesticides (Abstract A41). In Science in an Uncertain Millennium, R. Paulson, ed. Washington, D.C. 2000 Annual Meeting of the American Association for the Advancement of Science. Washington, DC. February 2000.

Schindler reported in a paper given at the AAAS annual meeting that persistent organochlorine contaminants that had been deposited in glacial snow are being liberated by melting. The implication of this work is that as climate disruption warms the Earth, rising temperatures will volatilize contaminants that had been trapped in what amounted to cold storage. These compounds are thus more likely to enter the food chain.

de Boer, J, PG Wester, HJC Klamer, WP Lewis and JP Boon. 1998. Do flame retardants threaten ocean life? Nature 394:28-29.

According to de Boer et al., brominated flame retardants "are used at relatively high concentrations in electronic equipment such as computers and television sets, in textiles, cars and in many other applications." In this study they report that two groups of these compounds, polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs), are found in multiple species of marine life, including sperm whales.

The presence of these compounds in sperm whales, which feed in the deep ocean, "indicates that the compounds have reached deep ocean waters, as sperm whales are not usually found in shelf seas."

They found "relatively high PBDE concentrations in a whitebeaked dolphin (>7 mg/kg) and in harbour seals (>1 mg/kg), which had been feeding in the North Sea and the Wadden Sea. PBDE levels in dolphins and seals indicate that ongoing industrial production of PBDEs may create an environmental problem similar to that caused by PCBs, which have been found at concentrations up to 128 mg/kg in marine mammals."

Tests they performed on persistence indicate that PBDEs may be even more persistent in the environment than PCBs.

They conclude by observing: "The presence of PBBs and PBDEs in sperm whales, the high levels of particularly PBDEs in seals and dolphins, and the on-going industrial production of these compounds suggest that an environmental problem may be on its way."

A study released in Japan in June 2000 reports high levels of PBDEs in people. More...

Blais et al. report that mountain regions in British Columbia far from sources of contamination accumulate organochlorine pesticides and PCBs in their snowpacks.

Snow that they sampled showed a 10- to 100-fold increase between 700 and 3,100 meters in altitude (right, from Blaise et al.).

Atmospheric deposition appears to be the only process that "can provide a plausible explanation for the observed contamination of fish in high-altitude Canadian lakes."

They raise important questions about water supplies for cities that depend upon snow pack accumulations, especially those dependent upon water supplies from high mountains. "For example, cities like Denver and Mexico City derive their water supply from snowmelt on mountains over 3,000 m high. They are also much closer to industrial and agricultural sources of contaminants in areas that reach summer temperatures 5-10° C warmer than those of western Canada. The effect of cold condensation on the fate of organochlorine in these areas remains unknown, but is likely to result in more pronounced accumulation of toxic compounds than we have observed in our study area."

Simonich and Hites report on the global distribution of 22 organochlorine compounds in more than 200 tree bark samples from 90 sites around the world. High concentrations of some of the studied compounds were found in developed and developing countries alike. Those compounds that are relatively more volatile tend to have greater global distribution.

"High concentrations of organochlorine compounds were measured in tree bark from the United States, Europe, India, the Middle East, Japan, Brazil, Australia, Taiwan, South Korea, and Russia.

Samples from agricultural areas of the midwestern and eastern United States showed high concentrations of contaminants, as did samples from agricultural areas in California and the southwestern United States. In Europe, contamination was consistently high in parts of Germany, Romania, Belgium the Netherlands and Denmark. In Japan, contamination was consistently high in and around Tokyo and lower in Hokkaido.

The organochlorine compounds found in the highest concentrations were the HCHs, the endosulfans, and p,p'-DDE (a degradation product of p,p'-DDT)."

Talk to us: email