Study reveals contrasting chemical contaminants in conventional and hydroponic produce

CHINA – A recent study comparing the presence of chemical contaminants in conventionally and hydroponically grown produce has found  pesticide residues in a larger number of conventional samples than in hydroponic samples, as well as significantly higher levels of lead and cadmium in conventionally grown produce. 

The study, conducted in China by the Institute of Agro-Food Standards and Testing Technology, Shanghai Academy of Agricultural Sciences, and School of Chemical and Environmental Engineering, Shanghai Institute of Technology also assessed and found Phthalate levels were consistent between conventional and hydroponic samples.

The research study analyzed 177 samples from four vegetable commodity groups and found that conventionally grown vegetables exhibited a higher pesticide residue prevalence than hydroponic samples.

Specifically, 84 percent of conventionally grown vegetables contained pesticides, while only 30 percent of hydroponic samples showed pesticide residues.

Moreover, conventionally grown vegetables were more likely to have multiple pesticide residues, with 51 percent of samples containing two or more pesticides, compared to just 7 percent in hydroponic samples.

The reduced need for pesticides in hydroponic operations, attributed to the absence of soilborne hazards, accounts for this disparity.

Interestingly, phthalate levels remained consistent between conventional and hydroponic samples, with no significant difference observed except in the celery category, where conventional samples exhibited higher phthalate levels.

Phthalates, ubiquitous contaminants, were detected in all samples, originating mainly from soil and mulch film in conventional farming and irrigation water in hydroponic facilities.

Heavy metal concentrations

One of the study’s most striking findings was the significantly higher levels of lead and cadmium in conventionally grown vegetables compared to hydroponically grown ones.

Lead concentrations were 16.0 to 14.1 times higher in conventionally grown lettuce and celery, and 8.6 to 9.2 times higher in conventionally grown tomatoes and cucumbers.

Heavy metal contamination, particularly lead, was more prevalent in conventional samples, with detection rates ranging from 69 to 91 percent. Soil and irrigation water were identified as the primary sources of heavy metal residues in conventional and hydroponic vegetables, respectively.

These findings underscore the potential benefits of hydroponic farming in mitigating chemical contamination in produce.

By minimizing reliance on pesticides and reducing exposure to heavy metals, hydroponic systems offer a promising avenue for enhancing food safety and quality.

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