Bramwell et al. 2022 - Urban garden produce and adult lead biomarkers

Bramwell and colleagues tested whether gardening on Newcastle urban agriculture sites with elevated soil Pb translated into higher adult Pb body burdens. The main paper reports blood, saliva, soil, tap-water, and diet findings; it also summarizes Pb concentrations in fruits and vegetables collected for the same study, with root vegetables showing the highest mean Pb range among crop groups.

Key numbers

Participants and biomarkers

The study recruited 72 adults: 43 urban agriculture site gardeners and 29 controls matched by sex and similar age. After excluding one gardener with an acute occupational/hobby-related exposure, gardener blood lead levels ranged from 0.6 to 4.1 ug/dL with a geometric mean of 1.53 ug/dL. Controls ranged from 0.7 to 2.9 ug/dL with a geometric mean of 1.43 ug/dL. The gardener/control difference was not statistically significant (p = 0.391).

One excluded gardener had a blood lead level of 11.4 ug/dL; follow-up linked that result to renovating leaded windows shortly before testing, and zinc protoporphyrin was not elevated.

Saliva Pb was not a reliable biomarker in this context. Mean paired saliva concentrations ranged from 1.3 to 7.9 ug/L among gardeners and from 1.1 to 4.5 ug/L among controls, but the collection devices had variable residual Pb and duplicate saliva samples varied substantially.

Soil and tap water

Nearly 280 soil samples were collected from 31 urban agriculture garden plots. The three sites had a soil Pb geometric mean of 327 mg/kg and a 95th percentile of 680 mg/kg. Home tap-water Pb ranged from 0.06 to 12.0 ug/L with a geometric mean of 0.43 ug/L. Participants reporting lead pipes or solder had a tap-water Pb geometric mean of 3.49 ug/L.

Produce Pb summarized in this paper

The paper states that fruit and vegetable Pb concentrations from the same study were published previously, then summarizes crop-group means on a fresh-weight basis. Root vegetable species had the highest Pb uptake, with species-mean values ranging from 0.005 to 0.50 mg/kg fresh weight and a median of 0.023 mg/kg fresh weight. Shrub fruit species means ranged from 0.009 to 0.025 mg/kg fresh weight, median 0.019 mg/kg. Green vegetable species means ranged from 0.009 to 0.069 mg/kg fresh weight, median 0.012 mg/kg. Herbaceous fruit species means ranged from 0.002 to 0.023 mg/kg fresh weight, median 0.006 mg/kg. Tubers, represented by potatoes, had a mean of 0.006 mg/kg and median of 0.002 mg/kg. Tree fruit, represented by apples, had the lowest uptake, mean and median both 0.001 mg/kg.

Diet associations

Eating more root vegetables and shrub fruit was associated with higher blood lead in the cohort, while eating more green vegetables and herbaceous fruits was associated with lower blood lead. The authors interpret the lower-blood-lead association as potentially consistent with protective effects of calcium, iron, and vitamin C rather than lower environmental exposure.

Methods (brief)

Blood samples were analyzed by ICP-MS in the UK Health and Safety Executive laboratory using certified reference materials. Saliva samples were acid-digested and analyzed by ICP-MS, but the method was limited by collection-device blanks and duplicate variability. First-draw home tap-water samples were acidified and analyzed for total Pb by ICP-MS. Urban agriculture site soil samples were collected around crop roots from 0-30 cm and analyzed for pseudo-total Pb by aqua regia digestion and ICP-OES. Fruit and vegetable consumption was estimated from an adapted food-frequency questionnaire using crop groups from the UK Contaminated Land Exposure Assessment model.

Implications

Certification: The produce values are useful as summarized urban-garden Pb occurrence context for vegetables and fruit, but they are not a full sample-level benchmark distribution in this paper because the detailed produce dataset is cited to a prior Entwistle et al. publication.

Courses: Useful example for separating biomonitoring, soil exposure, tap-water exposure, and produce occurrence evidence in one study.

App: Supports qualitative risk context that root vegetables grown in Pb-contaminated urban soils can have higher Pb uptake than above-ground fruits, but app-facing ingredient estimates should rely on the detailed produce dataset when available.

Wiki pages this source may touch

• root-tuber-vegetables
• non-root-vegetables
• fresh-fruit
• root-vegetables
• non-root-vegetables
• vegetables
• lead
• index

Verification notes

This page was built from the full PDF text, including the abstract, participant recruitment, biomonitoring methods, environmental sampling methods, results for blood Pb, saliva Pb, soil Pb, tap-water Pb, Table 3 consumption-rate context, and the discussion paragraph summarizing fruit and vegetable Pb concentrations. The source reports lead only. Produce values are summarized crop-group means from the associated Newcastle allotment study and are labeled here as summarized context rather than sample-level occurrence tables.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.