Heated tobacco products(HTPs): environmental risk assessment on HTP butt extracts

In order to study the environmental risk of extracts from the used tobacco butts of heated tobacco products (HTPs), the used HTP butts were extracted to study the acute toxicity on Selenastrum capricornutum, Daphnia magna, Brachydanio rerio and Eisenia foetida. The inherent biodegradability of the extracts in the environment and the bio-enrichment of nicotine in Brachydanio rerio in aquatic environment were also studied. The results showed that: 1) The inhibitory effect concentration of the extracts on the growth of Selenastrum capricornutum for 72 h exposure was 1.843 cig/L within the 95% confidence interval of 1.522-2.210 cig/L. Its 48 h acute activity inhibitory toxicity EC₅₀ to Daphnia magna was 0.665 cig/L within the 95% confidence interval of 0.601-0.736 cig/L, and its acute toxicity LC₅₀ to Brachydanio rerio for 96 h exposure was 2.236 cig/L within the 98.4% confidence interval of 1.0-5.0 cig/L. 2) The acute toxicity LC₅₀ of the extracts to Eisenia foetida for 14 d exposure was higher than 60 cig/kg (dry weight of artificial soil). 3) The cumulative biodegradation rate of the extracts was 81.09% in 28 d. 4) The bio-concentration coefficient (BCF) of nicotine in Brachydanio rerio was 4.74 in 0.05 cig/L aquatic solution. Under the condition of this experiment, the extracts of used HTP butts had certain aquatic biological acute toxicity, but no obvious terrestrial biological acute toxicity. The extracts were considered inherently biodegradable. The enrichment of nicotine in the extracts of used HTP butts was low, therefore the environmental risk of the extracts was relatively small.