Some highly toxic substances have been found in enameled decorations of beer, wine, and spirit bottles, according to results of a study by researchers at the University of Plymouth. The decorated enamels (opaque and semi-transparent protective coatings on the glass) of half of the bottles tested were found to contain high concentrations of lead and cadmium.
The findings reveal that cadmium concentrations of up to 20,000 parts per million were present in the decorated regions on a range of spirits, beer, and wine bottles. Furthermore, while the limit for lead in consumer paints is 90ppm, the researchers found that lead concentrations up to 80,000ppm were present in the décor of various wine bottles.
Researchers analyzed both the glass and enameled decorations on a variety of clear and colored bottles. The researchers say in the paper that their findings demonstrate how harmful elements are being unnecessarily used despite the presence of safe alternatives.
The findings state that the added potential for these substances to leach into other items during the waste and recycling process is an evident and additional cause for concern. Accordingly, selected samples were also subjected to a standard landfill leaching test. Results of the analysis show that the elements had the potential to leach from enameled glass fragments, and when subjected to a standard test that simulates rainfall in a landfill site, several fragments exceeded the US Model Toxins in Packaging Legislation and could be defined as "hazardous".
"Lead (Pb), Cadmium, Hexavalent Chromium (Cr(VI)) and Mercury (Hg) are highly toxic heavy metals that have come under intense scientific and medical scrutiny and increasing regulation over the past three decades. Restrictions are in place for the concentrations or mobilities of these metals in various consumer products, including toys, electronic equipment, ceramic products, and other food contact articles, jewelry, and paints, principally in order to protect human health and the environment. An additional rationale for limiting heavy metals in new consumer goods is to minimize the scope for introducing harmful chemicals into the recycling stream," says the paper.
Bottled alcoholic products were purchased from local and national supermarkets between September 2017 and August 2018 for the study. The bottles contained a variety of drinks (beers, wines, spirits) of volume that ranged from 50 ml to 750 ml. The results show that lead, cadmium, lead, and chromium were also all present in the glass, but at concentrations where their environmental and health risks were deemed to be of low significance.
The bottles were either clear, frosted, green, ultraviolet-absorbing green (UVAG) or brown with several being enameled over part of the exterior surface with images, patterns, logos, text and/or barcodes of a single color or multiple colors.
Out of the glass from 89 bottles and fragments analyzed using x-ray fluorescence spectrometry, 76 were positive for low levels of lead and 55 were positive for cadmium. Chromium was detected in all green and UVAG bottles, but it was present only in 40% of brown glass and was never in clear glass. The enamels of 12 products out of 24 enameled products tested were based entirely or partly on compounds of either or both lead and cadmium.
"The pervasive use of these heavy metals in what is largely a closed loop have potentially more serious impacts on the environment and the health of 287 workers employed in the glass recycling industry," say the researchers in the paper, adding that such obvious challenges must be factored into future legislation covering this area.
The findings were published in the Environmental Science and Technology journal.