A bill that would ban vaccines with a mercury-containing preservative is receiving fierce opposition from the medical community.

Senate Bill 2133, which was passed by the Legislature at the end of the session, is now awaiting a signature or veto from Gov. Linda Lingle.

Lawmakers were persuaded to pass the bill because of a potential link between mercury and autism, although studies by groups such as the Federal Drug Administration and the national Centers for Disease Control and Prevention have not found any connection between vaccines and the developmental disorder.

Medical professionals worry that instituting a ban would send the message to the public that the vaccines are dangerous.

"Any time you throw a cloud of doubt on the issue it makes it very difficult for healthcare practitioners to do the best that they can for the patients," said Dr. Chiyome Fukino, state health director.

However, Julianne King, a mother of an autistic child who has championed the bill, sees it differently.

"If we cannot trust the medical establishment, people will stop vaccinating — that's the issue at hand," she said. "So doctors should be trying to get mercury, a known neurotoxin, out of vaccines instead of fighting laws that would remove mercury."

King's husband, Don, said the study touted by the Centers for Disease Control and Prevention does not prove or disprove a link between mercury and autism, but suggests more study.

The Kings noted that a study by University of Washington researcher Thomas Burbacher on the effect of mercury in primate brains showed that injected ethyl mercury (the type used in vaccines) resulted in twice as much inorganic mercury than those given equal amounts by mouth of methyl mercury (the type found in fish).

Kalma Wong, a mother of autistic children who lobbied for the bill, said that the opposition is based on last-minute changes to the bill.

The intent of the bill was to limit the use of thimerosal vaccines and give preference for mercury-free vaccines to children and pregnant women. In the final version of the bill, however, the phrase "to the greatest extent" possible was eliminated, which creates a problem. "It said it was like a total ban; no one would get any of it," Wong said.

She points out, however, that even if there was a ban, the state could make exceptions in the case of a flu epidemic, shortages or other public health emergencies.

Nevertheless, the medical community has raised several objections, writing to the governor and calling in to her radio show.

Dr. Galen Chock, vice president of the American Academy of Pediatrics local chapter, is hoping for a veto. "This is not a good bill that would give a benefit to any child," he said.

Thimerosal, the mercury-containing preservative, has never been linked to human disease, Chock said. "It makes no sense to ban it in the state of Hawai'i," he said.

Chock said the methyl-mercury linked to disease is different from the ethyl-mercury used in thimerosal. The ethyl-mercury is excreted from the body faster, he said.

A ban would create problems with the influenza vaccine. Only 10 percent of the influenza vaccine produced in the United States is thimerosal-free, and most of it expected to be available next flu season has already been preordered.

"That would leave a lot of pregnant women without a vaccine," he said.

Fukino said she will send a recommendation to the governor this week. Lingle has not yet taken a position, but the Health Department opposed an earlier version of the bill.

Since scientific research has not determined that thimerosal causes autism, "We believe that the benefits of the immunizations outweigh the small theoretical risks," Fukino said.

A ban like this would reduce the supply of flu vaccine by 20 percent, she said. "This may be very important, especially if vaccines are in short supply or if there is an insufficient supply to meet the needs of the community," she said.

Other vaccines that contain trace thimerosal include diphtheria, tetanus and whole-cell pertussis, as well as the meningococcal vaccine.

"Vaccines are an important preventative measure that has good public health policy," Fukino said. "Any reasonable person would agree that there's a difference between known risks — in other words studies and documentation that there is a link — and where no link is actually documented."

Reach Treena Shapiro at tshapiro@honoluluadvertiser.com.