Table 1.
Summary statistics for henhouse characteristics and management practices and analytical results for 9 NYC henhouses and 1 rural henhouse
| NYC Henhouses (n=9 except where noted) | Rural Henhouse | ||||
|---|---|---|---|---|---|
|
| |||||
| Characteristics and Practices | Minimum | Median | Mean | Maximum | |
| Number of Chickens | 5 | 20 | 45 | 147 | 7 |
| Number of Laying Hens | 3 | 20 | 43 | 147 | 2 |
| Number of Chicken Breeds | 1 | 4 | 4 | 6 | 2 |
| Average Chicken Residence Time in Garden (months) | 5 | 12 | 17 | 36 | 36 |
| Average Number of Eggs per Laying Hen per Day | 0.1 | 0.7 | 0.5 | 0.9 | 0.4 |
| Run Area (m2) | 3 | 9 | 115 | 692 | 49 |
| Run Area per Chicken (m2) | 0.2 | 0.6 | 1.2 | 5.6 | 6.9 |
| Run Cover Material - Fraction of Run Covered by | |||||
| Bare Soil | 0% | 90% | 59% | 100% | 100% |
| Grass | 0% | 0% | 22% | 100% | 0% |
| Mulch (e.g., bark, straw, coffee chaff) | 0% | 5% | 19% | 85% | 0% |
| Fraction of time chickens have access to areas outside of henhouse and enclosed run | 0% | 1% | 11% | 50% | 0% |
| Diet - Fraction from | |||||
| Commercial Layer Feed | 20% | 75% | 71% | 90% | 90% |
| Food Scraps | 5% | 15% | 24% | 80% | 0% |
| Other (e.g. corn, grain, seed) | 0% | 1% | 4% | 15% | 10% |
|
| |||||
| Analytical Results
| |||||
| Number of Eggs Analyzed | 3 | 6 | 6 | 10 | 6 |
| Fraction of Eggs with Lead Detected (FPbEgg) a | 0% | 33% | 44% | 100% | 0% |
| Number of Chicken-Area Soil Samples Analyzed | 1 | 2 | 2 | 3 | 1 |
| Lead Concentration in | |||||
| Eggs (μg/kg) | |||||
| Minimum Egg from Henhouse | < 10 | < 10 | < 10 | 18 | < 10 |
| Median Egg from Henhouse | < 10 | < 10 | 13 | 40 | < 10 |
| Maximum Egg from Henhouse (PbEggMax) | < 10 | 26 | 45 | 167 | < 10 |
| Soil (mg/kg) | |||||
| Chicken Run (PbSoilRun) | 20 | 71 | 128 | 351 | 15 |
| Maximum for all Chicken Areas (PbSoilMax) | 51 | 94 | 220 | 631 | 15 |
| Exposure-Weighted (PbSoilExp) | 21 | 71 | 167 | 558 | 15 |
| Water (μg/L) b | < 5 | < 5 | < 5 | < 5 | < 5 |
| Layer Feed (μg/kg) | 111 | 128 | 156 | 272 | 92 |
| Kitchen/Garden Scraps (μg/kg) (n = 2) c,d | 224 | 1020 | 925 | 1530 | - |
| Other Feed (corn, grain, seed) (μg/kg) (n = 3)c | < 10 | 12 | 32 | 80 | < 10 |
| Calcium Supplements (μg/kg) (n = 4) c | 213 | 237 | 335 | 556 | - |
Detection limit for lead in eggs was 10 μg/kg. (For comparison, the US FDA detection limit for eggs is 7 μg/kg [26, 27])
Detection limit for lead in water is 5 ug/L. (For comparison, US EPA’s drinking water action level is 15 μg/L).
Henhouses with no analytical results for these feed/supplement materials were not considered in calculating summary statistics.
Kitchen/garden scraps: Total of three samples from two henhouses; one henhouse provided two samples.
Other feed: Total of three samples from three henhouses; one sample represented two henhouses, and one henhouse provided two samples.
Calcium supplements: Total of three samples from four henhouses; one sample represented two henhouses.
Kitchen scraps included acorn squash and cabbage; garden scraps included garden-grown callaloo (a leafy vegetable) and other vegetable scraps.