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The Best Science Writing Online 2012
Showcasing more than fifty of the most provocative, original, and significant online essays from 2011, The Best Science Writing Online 2012 will change the way...
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BOSTON—Exposure to lead—so toxic—is a problem of the past, right? Wrong. Since the U.S. took lead out of gasoline in 1976 and banned lead paint in 1978, most health scientists, regulators and the public have considered the problem largely solved. But ongoing testing shows that even though the average concentration of lead in the American bloodstream has dropped by a factor of 10 since the late 1970s, the levels are still two orders of magnitude higher than natural human levels, which have been determined by studying skeletal remains of native Americans dating to before the industrial revolution.
Equally problematic, recent health studies have shown that exposure levels previously thought to be “safe” were too high. Scientists from various disciplines are advising the Environmental Protection Agency and health departments to lower the concentration deemed acceptable in the bloodstream, which today averages 1.3 micrograms per deciliter but can be much higher for many individuals. The change is warranted because the latest set of long-term tests done over decades has revealed that many of the health complications from lead arise even at low exposures. Higher levels are not necessary to instigate damage to the body or brain, Joel Schwartz of the Harvard School of Public Health told a somewhat surprised crowd on Feb. 16 here at the annual American Association for the Advancement of Science (AAAS) meeting. Excessive lead exposure correlates with a host of ills, including impaired cognition, attention deficit disorder and lower academic test scores for children, psychiatric disorders, and increased blood pressure, hypertension and arrhythmia.
Lead is also increasingly implicated in dementia in the elderly. As we age, our bones demineralize and release calcium (which is why calcium supplements are often recommended, especially for women). “But the bones also release lead,” which accumulates in our skeletons over a lifetime, Schwartz said. “We don’t know if the brain can adapt to the higher levels” of lead in the bloodstream, he said, calling for new research to find out.
The ramifications of lead exposure are financial as well, costing the U.S. about $209 billion a year, said Jessica Reyes, an economist at Amherst College. The bill includes everything from direct medical costs to a heightened need for special education classes and incarcerations for violent crime, which also correlates with higher lead exposure.
The ongoing trouble with lead exposure is not to be confused with lead poisoning, which has dropped significantly in developed countries, including the U.S. The latter condition is caused by acute exposure at high concentrations, which can occur from eating lead paint chips. But all the other problems “are more like chronic diseases that build over time,” said A. Russell Flegal of the University of California, Santa Cruz. “We need to start thinking about the risks in that way.”
Lead is still prevalent in our environment for many reasons. Because lead does not degrade, heavy emissions from the past accumulate in soil. Winds, especially during drought—like that afflicting the Midwest for the past year or so—kick it up as dust, and runoff from heavy rains and flooding can re-suspend the particles in the atmosphere. Trees take up soil particles, too, but when forests burn in wildfires, as has been occurring more frequently worldwide with global warming in recent years, that lead is released back into the air. Fires also release lead from old houses and buildings coated with lead paint that was applied prior to the U.S. ban. Lead smelting and refining is still an enormous industry worldwide, sending more of the metal into the environment. Aviation gas used in planes still contains lead.
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19 Comments
Add CommentAnd then of course there is also all that ammo people are hoarding.
Reply | Report Abuse | Link to thisI would think hoarding ammo is fairly benign in terms of toxicity - at least it's not getting out into the environment that way. But this obviously depends on the future use of the stuff by the hoarder - he/she may use it to cause some very sudden and serious "lead poisoning", or may use it in a more traditional manner which over time will put it out in the environment. But even in the latter case, it doesn't seem like it would be a significant factor regarding the issue of toxicity.It seems that the toxicity issues involve breathing airborne particles and/or ingestion of dissolved particles, neither of which seems likely to occur from stored or expended bullets.
Reply | Report Abuse | Link to thisAnd I do realize that the comment by Cosmic had a different implication than just toxicity - a point which I appreciate as well.
I wonder how many thousands of tons of lead were released into the environment following the Tohoku Earthquake and Tsunami in Japan, by Oil & Gas fires, the Chiba Oil Refinery conflagration, automobiles, batteries, buildings burning and piles of debris were burnt in huge bonfires releasing lead, asbestos and other deadly substances into the air, sea and water. Funny how the mainstream media has been completely silent on these environmentally destructive effects, instead a total focus on the comparatively minor radioisotope releases from the Fukushima incident.
Reply | Report Abuse | Link to thisWe'll all die of catastrophic climate change long before all toxic contaminants could ever be removed from the environment. Sorry, the industrial revolution can't be undone and we can't all become Paleolithic peoples.
Reply | Report Abuse | Link to thisAre you claiming that forest fires are positively correlated with global warming? From what I understood, forest fires used to rage out of control from lightning strikes before we created our cities. Now, we fight them; we even do controlled burns. That is unnatural. The link in that section of text did not even operate as a citation to reinforce the claim.
Reply | Report Abuse | Link to thisOne thing the article fails to point out is that lead in large concentrations is fairly innocuous.
Reply | Report Abuse | Link to thisIt's when it's aerosolized into very fine particles that it becomes a problem.
The example of fishing weights is wrong, since they are large chunks of metal, not particles. The same is true for bullets fired when hunting.
Bullets fired at a range against steel targets may create some small particles, but they are extremely localized and never leave the target area of the range.
I would also be curious as to what percentage of the 30,000 tons per year ammunition and fishing weights actually make up.
Compared to enormous sources like used batteries and electronic waste they have to be a literal drop in the bucket.
Is this SciAm trying to drum-up a gun control agenda? I really hope not, especially on such flimsy data.
Then here's the citation for you:
Reply | Report Abuse | Link to this"Forest fire frequency and intensity have increased markedly since 1970. The 10-year average of boreal forest burned in North America, after several decades of around 2.5 million acres, has increased steadily since 1970 to more than 7 million acres annually."
http://www.usgcrp.gov/usgcrp/nacc/education/alaska/ak-edu-5.htm
Appreciate it! Relevant information is necessary to give a greater understanding of the whole picture. It seems even pests and disease will become a greater problem, but only in those formerly cold areas in that resource. Every where else will suffer as they always have.
Reply | Report Abuse | Link to thisThis article misses the point!! Scientific what??
Reply | Report Abuse | Link to thisToxicologists have known for years that flouride, still being added to 65% of municipal US drinking water due to an errant US Govt Policy, doesn't help tooth decay. However, this toxin tends to cause the human body to absorb more lead (often found in solder used for water piping). Please don't take my word on this. Find the documentary "Flouridation" and see for yourself!
Please keep your paranoid and silly nonsense confined to your John Birch Society meetings, please!
Reply | Report Abuse | Link to thisThe government makes no errors wrt toxins . It is deliberate .
Reply | Report Abuse | Link to this"sault:" Please wake up and get current on this relevant issue of artificial water floridation. A good start would be to check out this menu of science-based videos exposing this highly dubious hazmat water-dumping practice at:
Reply | Report Abuse | Link to thishttp://www.fluoridealert.org/fan-tv/prof-perspectives/
Repeating: Please see videos on the dangerous practice of fluoridation at:
Reply | Report Abuse | Link to thishttp://www.fluoridealert.org/fan-tv/prof-perspectives/
Hunters who use lead bullets (and others who eat the meat they bring home) have higher blood lead levels than hunters who use non-lead ammo.
Reply | Report Abuse | Link to thisOops, the documentary film is named "Flouridegate" and the directors interviewed retired govt. toxicologists, among others. Yes, flouride currently being added to US water supplies is a waste by-product from the chemical fertilizer industry in Mexico, China and other point east. It is a known neurotoxin, lowers IQ in developing brains, and tends to effect the youngest (smallest) members of society the most. Also known to suck lead into the human body, as commented earlier.
Reply | Report Abuse | Link to thisOnce govt. policies are in place, difficult to disband due to possible serious legal repercussions. By the mid-90s, adding flouride to water supplies was regarded as being based on junk science, the allowable ppm level in water had been "adjusted" to suit a policy, not human health. Hopefully these tidbits are enough to start your own research...
Lead wheel weights have been used on vehicles in the United States since the 1930s. Some are recycled, some are collected and melted down to make bullets and sinkers. The United States Geological Survey (USGS) estimates that each year 2,000 metric tons of lead in wheel weights is lost on US highways. The fate of these lost lead wheel weights in cities is a potential continuous source of lead contamination to urban areas and small towns. Lead wheel weights lost on roadways are abraded and broken by traffic. Dust and particles from the abraded lead can be flung onto urban soils or washed into streams.
Reply | Report Abuse | Link to thisSee: Root, Robert A., 2000, Lead loading of urban streets by motor vehicle wheel weights. Environmental Health Perspectives, 108, 937-940.)
Hollabaugh, Curtis L., 2013, The effect of steady state deposition of lead wheel weights on lead distribution in the environment. Geological Society of America, Abstracts with Programs, Vol. 45.
Roger Masters from Dartmouth has posited the theory that drinking milk helps reduce blood led levels. He then suggests that populations who are unable to drink milk, because they had no cows in their countries of origin are unable to digest milk, and as a result have far higher blood led levels, with resulting higher incidence of cognitive deficits (and lower so-called "IQ"), and possibly ADHD. An interesting and testable theory.
Reply | Report Abuse | Link to this"Hunters who use lead bullets (and others who eat the meat they bring home) have higher blood lead levels than hunters who use non-lead ammo."
Reply | Report Abuse | Link to thisSources? Or is this your personal theory?
AVGas is currently .18% of all gasoline produced. To blame the lead in avgas is misleading. While I understand that it isn't lead free, the amount placed into the environment through other means is far more damaging. AVGas is currently used on light aircraft that do not fly near as much as their bigger breathern.
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