RightNow.final 4/8/04 6:59 PM Page 12

RightThe expanding Now Harvard universe

HEAVY METAL BLUES

mother. When the children were seven Mercury on the Brain years old, researchers measured mercury levels in their hair and blood, measured their heart rates, and tested developmen- he pregnant women did not Grandjean’s work, one of the first tal variables like the speed at which their worry about their food. They prospective studies of mercury-exposed brains responded to auditory signals. The simply ate it: chunks of fresh whale children, began almost 20 years ago. He examinations were repeated at age 14. meat and pounds of fish. They ate and colleagues from Europe and Japan Grandjean reports that mercury seems it because they were hungry. They identified 1,022 Faroese children who to slow the brain’s response to sound. ateT it as their mothers had, as their were particularly vulnerable to mercury Somewhere along the transmission line— ancestors had, for centuries. They did not because their mothers’ diets included from ear to auditory nerve to brain—the know the meat carried an invisible pilot whale meat, a traditional—and signal is delayed. Some children’s auto- poison that would damage their unborn often highly contaminated—Faroese nomic systems also seem less able to reg- babies’ brains and disrupt the beating of food. Researchers measured mercury in ulate heart-rate variations. The changes their hearts. the pregnant women’s hair before the seem irreparable, Grandjean says. “At age Today those babies, born on the Danish children’s births; some had up to 50 times seven, we saw that the more mercury Faroe Islands in the North Atlantic, are more mercury than the average U.S. they were exposed to in the womb, the teenagers—and living testaments to mer- cury poisoning. In two recent papers published in the Journal of Pediatrics, Philippe Grandjean, adjunct professor of environmental health at the School of Public Health, has begun unraveling mercury’s toxic e≠ect on their brains. His results confirm that children ap- pear most at risk in the womb, where mercury seems to deform the brain’s frag- ile architecture and upset the maturation and migration of brain cells. But Grand- jean also found that mercury could threaten children’s nervous systems well into adolescence. “What we are finding out is that mercury is very parallel to lead,” Grandjean says. “Such pollutants are particularly worrisome because, once they’ve done the damage to the develop- ing brain, the child will have to live with that for the rest of his life.’’ Swordfish and tuna steaks on sale in a super- market. Ocean predators like these may con- centrate mercury in their tissues.

12 May - June 2004 RightNow.final 4/8/04 6:59 PM Page 13

Right Now

worse they were o≠ in terms of language also underscores a more dis- The small coastal village of Eysturoy in the Faroe Islands, located in the North skills, attention span, motor speed, turbing picture: of humans Atlantic midway between Iceland and things like that.” Seven years later, there adrift in a sea of potentially Norway. Seafood is a staple of the diet here. was no evidence that the children’s bod- brain-damaging chemicals ies had recovered or compensated for the they have manufactured but damage. What’s more, the data suggest don’t fully understand. “This that as the children matured and began is much more serious than eating mercury-tainted whale meat and telling pregnant women to other seafood themselves, the brain dam- avoid eating canned tuna age continued—even at relatively low ex- fish,” he says. “There are posure levels. “Our concern is that we are about 150 substances I can now seeing evidence that the brain’s sus- recite that are known to be ceptibility is not just limited to the fetal toxic to the human brain. period,’’ says Grandjean. “The brain is Out of those substances… still vulnerable throughout childhood we’ve looked at three—lead, and into the teenage period. This is an mercury, and PCBs [polychlorinated passed phasing the metal out of such entirely new observation.’’ biphenyls].” products. “There was tremendous resis- In the United States and other nations, Grandjean believes other chemicals tance to regulating lead,” Grandjean re- mercury’s harmful e≠ects have been that haven’t yet been thoroughly re- members. “I also see resistance to regulat- known for years. It is outlawed in ther- searched share mercury’s toxic traits. He ing mercury. Are we going to take another mometers and regulated by environmental worries that governments and health or- 20 years to look at another chemical? We agencies; pregnant mothers are warned ganizations will be slow to realize new have to find a way to use our best judg- away from potentially contaminated threats to young brains, and he speaks ment and eliminate the types of expo- seafood. Still, mercury hasn’t fueled the from experience. In the 1970s, as a medical sures that can harm the nervous system. same public outcry as lead, a neurotoxin student studying lead poisoning, he sat You don’t get a second chance to build with a devastating and well-documented through government hearings as the your brain.” neil shea legacy. In fact, critics of Grandjean’s study United States faced a poison that seemed charge that there is little cause for alarm ubiquitous: in lead-based paints, gasoline, philippe grandjean website: because most of the rest of the world and leaded cans and pipes. It took nearly www.hsph.harvard.edu/faculty/ doesn’t share the Faroese taste for whale. a decade before meaningful laws were PhilippeGrandjean.html Grandjean disagrees. First, he says, whales aren’t the only animals that “bio-

accumulate” the poison. Across the globe, THE DA VINCI MODE for example, inorganic mercury is belched into the atmosphere in smoke from coal-fired electricity plants and garbage incinerators. (China, for exam- Ideas Rain In ple, fuels its booming economy with a mercury-rich form of coal and is one of n 1675 Isaac Newton su≠ered a thinkers have wrestled with this enigma, the chief mercury polluters.) It returns to mental breakdown—some modern usually on a purely speculative basis. earth in rain, where microorganisms ab- psychiatrists diagnose him as a Now, a new empirical study suggests a sorb it. Small fish graze on the microor- manic-depressive—and he was still specific style of cognition shared by those ganisms; larger fish, like mackerel, eat the recovering in 1679. But long before who hear the Muse and those who merely grazers; and then top marine predators that,I Newton had already invented calcu- hear voices. The research also suggests such as whales, sharks, tuna, and lus and formulated his law of gravita- variables that distinguish the two groups. swordfish eat the mackerel. Because this tional attraction. Throughout history, ge- In a paper published in the Journal of grand digestive process doesn’t reduce or nius and madness have often dwelled Personality and Social Psychology, lecturer on expel mercury, it concentrates in fish at together: think of Vincent Van Gogh, psychology Shelley Carson, Ph.D. ’01, the apex of the food chain—where hu- William James, M.D. 1869, and, more re- Harvard graduate student Daniel Hig- mans often dine. Freshwater fish also ac- cently, mathematician John Forbes Nash gins, and Jordan Peterson of the Univer- cumulate the heavy metal, especially in (portrayed in the book and film A Beautiful sity of Toronto (formerly assistant pro- New England, which has become a land- Mind). Delusional psychosis and inspired fessor of psychology at Harvard) focus on ing zone for air-borne mercury from creativity, ostensible antipodes of human “latent inhibition,” a cognitive mecha- power plants in the Midwest. experience, ironically also seem to be nism discovered as a result of experi- Grandjean stresses that his research next-door neighbors. Over the centuries, ments with animals in the late 1950s. La-

Photographs by Corbis Harvard Magazine 13