Year “7” and Year “8” Studies Focusing on Mulch

Early research has shown that mulches made from recycled dimensional wood can be contaminated with CCA (Townsend et al. 2003). Follow-up study -> Year 7 – South Florida – mulches from stores Year 8 – Rest of Florida – mulches from stores Study to evaluate impact of colorants Mulch – Buffer Materials

Gary’s Focus Shiba’s Focus Playground Mulch

Mulch made from C&D Wood

Mulch Analysis Methods Sample Visual Inspection Size Distribution Ash for Total Metals SPLP Analysis Chemical Analysis Physical Analysis

Visual Inspection

Objects Found in Mulch  Nails  Plastic  Rubber  Glass  String  Rocks  Etc.

Size Distribution  Uniformity Coefficient (UC):  The UC will approach 1 if the pieces of sample are the same size   d 50 : The size in inches that 50% of the sample is finer than

Sieve Analysis

Results: Visual Inspection  52% are colored mulches  17% mulches contained plywood  73% mulches with plywood are colored

Results: Size Distribution  Average d 50 of samples is 0.29 in.  Average Uniformity Coefficient is 5.0 Frequency %

Results: Size Distribution

Chemical Analysis Sample Visual Inspection Size Distribution Ash for Total Metals SPLP Analysis Chemical Analysis Physical Analysis

Analysis Procedure Total Metals Results Leachable Results

Methods: Ash for Total Metals

Ashed Samples: Results: Ash for Total Metals As > 3.7 mg/kg ColoredNot Colored As < 3.7 mg/kg As > 3.7 mg/kgAs < 3.7 mg/kg

ColoredPlywood Number of Samples > 3.7 mg/kg Arsenic > 10 mg/kg Arsenic > 50 mg/kg Arsenic > 100 mg/kg Arsenic 2512 % 4 %0 % √2015 % 5 %0 % √3 √√1070 % 30 % Open Bin 367 % Pine Bark 277 % 4 %0 % Results: Ash for Total Metals

Concentration Range of Arsenic Samples Frequency %

Arsenic vs. Chromium

SPLP Results

Methods: SPLP Analysis

SPLP Samples: Mulch SPLP Results Positive for Arsenic ColoredNot Colored Not Positive for Arsenic Positive for ArsenicNot Positive for Arsenic

SPLP Table ColoredPlywood Number of Samples > 12  g/L Arsenic > 50  g/L Arsenic > 100  g/L Arsenic 3716 %5 %3 % √3421 %3 % √425 %0 % √√1182 %73 %45 % Open Bin475 % 50 % Pine Bark4522 %4 %0 %

Concentration Range of Arsenic Samples Frequency %

Arsenic vs. Chromium

Conclusion  52% are colored mulches  36% colored mulches positive for arsenic  17% mulches contained plywood  67% mulches with plywood positive for arsenic  73% mulches with plywood were colored  82 % of colored mulches with plywood contained arsenic  44 % of South Florida samples detected positive for arsenic in SPLP analysis  75 % of open bin mulches contained high concentrations of arsenic

Conclusion  Engineered wood was found in 21% of consumer mulches  Arsenic was found in 28% consumer mulches  SPLP tested showed that arsenic leached from 27 % of consumer mulches  48% of these samples leached over 50 μg/L

Questions?  Report will be available in the next couple of months