Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was studied?
This original research article investigated the bioavailability and speciation of arsenic in carrots grown in soils contaminated by industrial wood preservation activities. The primary aim was to determine the extent to which arsenic and its chemical species are taken up by carrots cultivated in soils with varying arsenic concentrations, and to assess the potential health risks associated with consuming such carrots. The study involved growing carrots in seven experimental plots, each with mixtures of arsenic-contaminated and uncontaminated soils, with arsenic concentrations ranging from 6.5 to 917 mg/kg (dry mass). The researchers analyzed both the total arsenic and its species—primarily arsenite (As III), arsenate (As V), and methylated forms—using high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC–ICP-MS). The study also included copper as a co-contaminant and assessed its uptake in carrots. The outcomes were evaluated in relation to Danish and WHO guidelines for tolerable arsenic intake, making the findings directly relevant for heavy metal certification programs and food safety standards.
Who was studied?
The research focused on carrots (Daucus carota) as the test crop, chosen for their known tolerance to water-soluble arsenic and their status as a widely consumed vegetable. Carrots were grown in experimental plots containing soil sourced from a former industrial wood preservation site in Denmark, which had been contaminated with arsenic and copper. The soils were prepared by mixing highly contaminated and uncontaminated soil samples to create a gradient of arsenic concentrations. No human or animal subjects were involved; rather, the study’s “subjects” were the carrots grown under controlled conditions and the corresponding soil samples from each plot. The harvested carrot samples were separated into core and peel and analyzed to determine the distribution of arsenic and copper within the edible portions. Thus, the study design allows extrapolation of the findings to real-world agricultural scenarios involving root crops grown in contaminated soils.
Most important findings
| Critical Points | Details |
|---|---|
| Arsenic uptake and growth effects | Carrot growth was increasingly depressed as soil arsenic rose from 6.5 to 338 mg/kg; no carrots developed in soils above 400 mg/kg arsenic, indicating phytotoxicity at high contamination. |
| Arsenic species in soil and carrots | In less contaminated soils (6.5–30 mg/kg), arsenite (As III) predominated; in more contaminated soils (93–338 mg/kg), arsenate (As V) dominated. In harvested carrots, As III and As V were found in similar concentrations, with no methylated arsenic species detected in either soil or carrots. |
| Bioavailability of arsenic | The soil-to-carrot arsenic uptake rate averaged 0.47 ± 0.06% of the total soil arsenic content. Relative to extractable arsenic in soil, uptake was about 580%. |
| Distribution within carrot tissues | Arsenic concentrations were about three times higher in carrot peels than cores, suggesting external tissues accumulate more arsenic. |
| Copper uptake | Arsenic concentrations were about three times higher in carrot peels than in cores, suggesting external tissues accumulate more arsenic. |
| Health risk assessment | Consuming carrots grown in soils with 30 mg/kg arsenic resulted in an estimated weekly intake of 37 µg inorganic arsenic, about 4% of WHO’s provisional tolerable weekly intake (PTWI). However, carrots from more contaminated soils would pose a significant risk. |
| Regulatory relevance | The findings support the Danish EPA’s soil quality criterion of 20 mg/kg arsenic for safe vegetable cultivation, as carrots grown at or below this threshold did not pose a toxicological risk based on measured arsenic uptake. |
Key implications
The study demonstrates that arsenic, primarily in toxic inorganic forms, is bioavailable to carrots grown in contaminated soils, though uptake is low relative to soil levels. This supports the use of strict soil arsenic thresholds in heavy metal certification programs to ensure crop safety and prevent excess dietary exposure to inorganic arsenic from root vegetables.
Citation
Helgesen H, Larsen EH. Bioavailability and speciation of arsenic in carrots grown in contaminated soil. Analyst. 1998;123:791-796.
