Household dust found in Malta has twice the level of a chemical used in fireworks as does China, according to a study by expert Alfred Vella.
The concern over perchlorate comes from its known interference with thyroid function and its strong presence in groundwater and food. Perchlorate is one of the more important chemicals used in fireworks and has no regulatory limit. The levels of perchlorate in dust in Malta “increase dramatically during the summer when compared to other months”.
This “is strong evidence” it originates from aerial and ground fireworks during village feasts, said Prof. Vella, who headed an inquiry in September 2010 following a spate of tragic fireworks accidents.
The study, co-authored by Cynthia Chircop, Tamara Micallef and Colette Pace, looked into the levels of perchlorate in dust collected directly as it precipitated from the atmosphere (or ‘dust fall’) and dust collected from households in 43 towns and villages in Malta and Gozo over a span of three years.
The concern over perchlorate comes from its known interference with thyroid function and strong presence in groundwater and food
It established that low levels of perchlorate are found in dust from December to March. This starts to increase around May and peak in July and August, to fall away “slowly and, most significantly, incompletely, beyond September into the next autumn and winter”.
This shift “clearly mimics” the calendar of religious feasts that peak from June to early September and “strongly suggests that fireworks are the main source of perchlorate in dust fall in Malta”.
The fireworks festival held in April in Valletta affected the small increase of perchlorate found in May’s dust fall.
The researchers noted that there were no industrial uses of perchlorate locally. It is imported solely for fireworks manufacture.
Malta has a “zealous pyrotechnical community of over 1,500 enthusiasts” who manufacture fireworks as a hobby, and these “skilful enthusiasts” competitively display their wares in ground and aerial shows over the summer during the feasts, the report said. There are more than 85 displays between June and September.
Apart from fireworks displays in village feasts, a week-long fireworks festival has been held in April since 2001.
However, even after the festa period is over and no new perchlorate is introduced into the atmosphere, the chemical still “persists” in urban dust, even in the samples taken in March.
This “demonstrates that, in this country, fireworks exert a significant impact on environmental quality,” the report said.
The chemical’s persistence is probably the result of resuspension of contaminated settled dust in the urban environment.
The values of perchlorate in indoor dust are almost twice that of China and almost seven times that of Korea.
“It is clear that the situation in Malta is worse in comparison with these countries and suggests that the source of the pollutant in this small country is unusually strong,” the report noted. This means people may be “exposed to a dietary dose of perchlorate from dust which remains significant” beyond fireworks season.
Dust is only one source of exposure; others include food, water and milk products.
The concern about perchlorate exposure in Malta “is heightened by the fact that the population appears to be constantly in contact with the chemical at some level throughout most of the year,” the report found.
The study called for precautions before taking any action on a national scale to manage the risk from fireworks, in a country “where pyrotechnics are an important cultural reality”.