HEALTH-BELARUS: Chernobyl Increased Thyroid Disease

By IPS Correspondents Reprint | | Print |

Judith Perera

LONDON, Sep 6 1998 (IPS) - Young people in Belarus exposed to radioactive iodine isotopes released during the 1986 Chernobyl nuclear disaster are much more likely to develop thyroid disease than children who escaped heavy radiation exposure.

A new study, detailed in the current issue of the prestigious British medical journal The Lancet, found that young men and women whose blood was tested 6-8 years after the disaster, were much more likely to have antibodies that threaten the thyroid gland.

The thyroid gland in the neck releases a hormone that reglates growth and metabolism; it is especially susceptible to damage by irradiation before puberty.

The study, by Dr Furio Pacini from the Department of Endocrinology at the University of Pisa in Italy, suggests that even if these young people had no thyroid problems at present, the antibodies were a ticking timebomb in their bodies, threatening future auto-immune thyroid diseases.

They are especially at risk of developing hypothyroidism – a decline in production of thyroid hormone, causing a slow metabolic rate resulting in weight gain and sleepiness.

The conclusions follow recent calls from World Health Organisation (WHO) experts for more funds for more studies into the effect of iodine isotope radition exposure amony young people who grew up in areas polluted by the fallout from the 1986 disaster.

Keith Baverstock, a radiation scientist at the WHO European Centre for Environment and Health in Rome, urges more funding for more research. He says that existing studies have already have changed the way scientists assess the risks posed by iodine-131 (I- 131), a radioactive isotope released during the process of nuclear fission.

Dr Pacini and colleagues from Italy and Belarus carried out thyroid-function tests and measured thyroid auto-antibodies in two groups of young people who were 12 years old or younger at the time of the Chernobyl disaster.

One group was from the village of Hoiniki, which was heavily contaminated with radioactive fallout, and a second group from the village of Braslav, which received only negligible contamination.

The investigators found no significant differences in thyroid function between the two groups. But of the 287 young people from Hoiniki, 56 (19.5 percent) had thyroid auto-antibodies, compared with only eight (3.8 percent) of the 208 from Braslav.

Pacini also cites figures which show that the levels of antibodies increase among young women, linked to the increase in the hormone oestrogen that occurs with puberty. Oestrogen is thought to have a role in the increased susceptibility to auto- immune diseases in women.

The risk of auto-immune disease adds to the burden on medical services in Belarus, the Ukraine and Russia, where high levels of thyroid cancers among young people living in the 1986 irradiated areas have already been recorded.

According to Ukrainian officials, there are more than 1,000 registered cases of thyroid cancer among children in the areas hit by Chernobyl’s fallout. Belarusian Minister of Health Ihar Zelyankevich has reported 574 cases of thyroid cancer among children in Belarus since 1986.

In another study, Dr Yuri Nikiforov and colleagues from the Division of Endocrinology at Cedars-Sinai Medical Centre in the University of California School of Medicine examined 151 cases of five- to 18-year-olds with thyroid lesions.

They found that the highest number of patients that subsequently developed thyroid cancer was in the group that was less than one year of age at the time of Chernobyl, and this number decreased progressively up to the age of 12 years.

Fifty-two percent of children with cancer and 24 percent with benign tumours came from the Gomel region, the area most contaminated by Chernobyl in Belarus.

A countrywide programme has now been started in Belarus based at the Institute of Radiation Medicine in Minsk, to investigate links between susceptibility to iodine 131 irradiation and goitre, the swelling of the thyroid gland.

Backed by Baverstock’s office, the programme involves the examination of 11,000 children and adolescents aged six to 18 years from 30 schools in urban and rural areas.

In Ukraine a three-year, four-million-dollar project has just been launched, funded by the United States Agency for International Development (USAID). The aim is to provide Ukraine’s health care service with up-to-date methods of early detection of thyroid cancer as well as the necessary equipment to treat the disease.

The aid programme will concentrate mainly on rural areas, where the health care system is underdeveloped.

But some experts have suggested that the high levels of thyroid cancer in Belarus and the Ukraine could have been avoided. Marvin Goldman, Professor Emeritus of Radiobiology at the University of California-Davis School of Medicine says it was a “high crime” that the consumption of milk was not banned in affected areas after the accident.

“The cases of childhood thyroid cancer could have been largely prevented if the authorities had supplied powdered milk, for instance,” he says.

The U.S. government’s own study of dangers to public health from nuclear testing in Nevada in the 1950s, found that the tests left ‘hot spots’ of radiation across the country that may have exposed up to 75,000 people to higher risks of thyroid cancer, especially children who drank large quantities of milk from local cows.

The U.S. National Cancer Institute has been criticised for not warning the public sooner of the findings. The study found that children in Nevada were exposed on average to two rads of radiation, about five times the amount emitted by a breast scanning machine.

But in several ‘hot spot’ areas, children were exposed to up to seven times the average dose. Some youngsters who drank large amounts of milk, received as much as 300 rads.