Jun 23, 2016
Water quality in the world of FSMA

The recent winter’s rains may have provided some relief from the drought, but the implementation of the Produce Safety Rule under FSMA will introduce a new water issue for food growers. Under this regulation, FDA has established water quality and testing provisions for agriculture.

Using the EPA recreational water standards, FDA has established microbiological criteria (or limits) for generic E. coli for irrigation and other farm uses covered under the Produce Safety Rule. Dr. Samir Assar, FDA’s Produce Safety Division Director, says these standards are founded on EPA data linking illnesses to fecal contamination of recreational water. Generic E.coli is a recognized indicator of animal and human fecal contamination, and Dr. Assar notes that “agricultural water is estimated to be the most important pathway of contamination”.

Under the final rule, there are two basic criteria for microbiological water quality. The first standard allows no detectable generic E. coli in water used for critical applications; these includes handwashing, water with direct contact of produce during or after harvest (including ice) or used on food contact surfaces, and irrigation water for sprouts. The use of untreated surface water for these applications is prohibited. Untreated ground water can be used for these applications, if it is E.coli-free and is sampled using the protocol outlined below.

The second set of criteria apply to agricultural water applied to growing produce other than sprouts. Untreated water used for these applications must have a geometric mean (GM) level of 126 generic E.coli or less per 100 mL of water, measured in CFU (colony forming units). In addition, 90% of the results must fall below a statistical threshold (STV) of 410 CFU per 100 mL.

Combined, the GM and STV measure the typical amount and variability of generic E. coli in an agricultural water source. The geometric mean is a type of average that measures the central tendency or average amount of E.coli in the water-it is less affected by isolated spikes in bacterial counts than the more familiar arithmetic mean/average we are used to. The STV accounts for adverse conditions that can impact the average water quality, such as rainfall events that wash debris into canals.

Testing for generic E. coli must use accepted test methods (21 CFR §112.151) and the appropriate sampling plan. For untreated surface waters, farms must collect and test 20 or more samples as close as possible to harvest over the course of 2-4 years. The GM and STV are calculated from this initial set of data to determine if the water is in compliance and to establish a “microbial water quality profile”. After this baseline is established, an annual survey of 5 or more samples per year is conducted. These 5 samples are combined with the 15 most recent previous samples to create a “rolling dataset” and calculate an updated GM and STV. For groundwater, a minimum of 4 samples must be collected and analyzed during one year and as close to harvest as possible in order to establish the baseline profile. The annual survey requires at least one groundwater sample to be tested and combined with the 3 most recent previous samples to update the GM and STV.

Growers supplied from a public water system, as defined by the Safe Drinking Water Act (40 CFR part 141) do not need to do this testing, providing documentation establishes the system’s compliance. Data from other parties may also be used, provided that the samples adequately reflect the water source used by the farm and meet the requirements for sampling (frequency, number of samples, test methods).

What happens if the water turns out to have a higher E. coli level than permitted? The Produce Safety Rule requires corrective actions be taken “as soon as is practicable” but no later than the following year to bring the farm water system into compliance. In the meantime, growers have the option of calculating microbial die-off between the last irrigation and harvest, using an estimated die-off rate of 0.5 log (3-fold) CFU per day for up to a maximum of 4 days. If the resulting calculated values of GM and STV are below the maximum limits then the water can be used as is. If the values are still too high, then the water must be treated; alternatively, the grower must demonstrate that sufficient die-off occurs between harvest and the end of storage or that processing activities will remove the contaminants.

When will these requirements take effect? For very small farms ($25,000 to $250,000 in annual produce sales), the compliance date is six years after January 26, 2016, the effective date of the Produce Safety Rule. For small farms ($250,000 to $500,000 in annual produce sales) the compliance date is five years after the effective date, or January 2021. Larger farms with more than $500,000 in annual sales must comply within four years of the effective date, or January 2020. Sprout farms face compliance dates ranging from one to three years after the effective date, depending on the size of the operation.

For surface water supplies to larger farms, the first samples can be collected this year to begin building the baseline data set. Growers using groundwater and/or with smaller operations should begin testing to evaluate their farm water supplies for compliance and identify any corrective actions that might be needed.

Source: Dried Fruit Association of California

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