Environment / Experts say autism diagnoses have reached epidemic proportions, with Hawai’i rates at the high end of the national average. Another statistic: Hawai’i residents eat fish at rates at least twice the national average. While no hard evidence has yet emerged linking the two, some are concerned about the possible connection.

Across the country, the numbers of children born with autism rates are rising at an average of 10 to 17 percent per year, says Marilyn Jakeway, acting educational specialist for autism at the Department of Education. Over the last five years, Hawai’i’s average yearly increase was 15 percent. According to the National Autism Association, the national autism rate has grown from one in every 10,000 to one in every 166 over the last 20 years. While the total number of local autistic children is unknown due to the lack of a tracking system, Naomi Grossman of the Autism Society of Hawai’i says that up to 4 percent of Hawai’i’s children with disabilities may have autism–nationally, that number is closer to 1 percent. Why are our state’s rates high, and what is responsible for the rising rates in general?

Some point to genetic factors, but genetics don’t cause epidemics. What does cause epidemics is large-scale contamination, and there is some evidence that mercury, combined with genetic malfunction, is behind the rise in autism rates. Studies supporting a relationship between mercury levels and autism rates have shown damage to brain structure and cell function in autism to be identical to that in mercury poisoning.

While mercury does occur naturally, experts say levels have gone up 1.5 percent per year since 1970. It is estimated that 60 to 75 percent of this increase is attributable to man-made sources such as fossil fuels and municipal and medical waste incinerators. A by-product of combustion is mercury, which bacteria turns into a neurotoxin called methylmercury. Fish absorb the methylmercury, and from there it is passed up the food chain, where it accumulates in animal tissue and can be passed on to whomever consumes that tissue.

Vaccines, another source of mercury, have been the focus of major lawsuits against pharmaceutical companies. During the 1990s, the number of vaccines on the Federal Immunization Schedule nearly tripled, while the numbers of children diagnosed with autism skyrocketed. Because symptoms appeared about the time kids received vaccinations, concern arose over Thimerosal, a methylmercury-based preservative that increases the shelf life of vaccines. Some studies have shown that low doses of Thimerosal negatively affect chemical reactions needed in neurodevelopment, while others suggest that the more Thimerosal a child received in a year, the higher the likelihood that the child developed autism.

The Center for Disease Control and the Food and Drug Administration ordered an end to the use of Thimerosal in 1999, but no recall was issued–vaccines containing Thimerosal remain on the shelves. Government and industry officials continue to deny the link to autism, and critics don’t foresee a reversal of this stance. To do so, they say, would be to jeopardize the credibility of the multi-billion dollar pharmaceutical and medical industry.

Suspicion also centers on dental fillings called amalgams. These ’silver’ fillings are banned or restricted in Europe but remain in wide use by dentists in the United States.

The canary swims

The use of amalgams and vaccinations, however, is consistent between Hawai’i children and those on the mainland. Speculation has thus focused on the state’s higher rate of fish consumption.

In 2003, Department of Health toxicologist Barbara Brooks measured methylmercury concentrations in popular fish found at auction. Brooks found that in all but one species, levels paralleled those nationally. That one species–opah, or moonfish–registered 30 to 55 percent more mercury than the other samples. Brooks says more investigation is needed to ascertain the reason for that discrepancy, but a 1977 study on the still-polluted Ala Wai Canal might shed some light. Mercury increased more than 100-fold in shrimp and polychaetes (marine worms) during the rainy season when urban runoff entered the ocean. Opah, unlike the other fish tested, prefers life at the bottom. Its diet? Shrimp and polychaetes. Still, Brooks suspects volcanic activity may be the source of higher mercury levels.

Princeton geochemist FranÁois Morel also failed to connect mercury to seafood in his 2003 research, which determined mercury levels to be on par with fish samples gathered 27 years ago. Morel, however, tested mercury levels only in yellowfin tuna (’ahi), migratory fish he caught at least 50 miles offshore. He admits his findings might not extend to coastal fish.

A toxic marinade

Assuming rising mercury levels are behind the national autism epidemic, and volcanic eruptions and fish consumption haven’t changed dramatically in the last 15 years, Hawai’i’s higher-end autism rates may mean there is more mercury in our environment than suspected.

The Environmental Protection Agency reported power plants and refineries released 435 pounds of mercury in Hawai’i in 2003. Yet 1/70th of a teaspoon per year is enough to render lake fish unsafe to eat, according to the US Public Interest Research Group. Meanwhile, other significant sources like waste incineration, sewage spills and sludge, sugar cane farming and combustion, construction debris and junk cars. Unlike other states, Hawai’i doesn’t monitor mercury emissions, assuring that for now the deadly toxin will be neither regulated nor reduced in Hawai’i.

To download the Department of Health fish advisory, go to www.hawaii.gov/doh or call 586-4651 for a pamphlet.