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Federal Register / Vol. 86, No. 40 / Wednesday, March 3, 2021 / Rules and Regulations
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PPRTV assessment also summarizes the results of several studies in mice and rats that have not demonstrated evidence of methyl bromide-induced carcinogenic changes USEPA, 2007a;
NTP, 1992; Reuzel et al. 1987; ATSDR, 1992. In 2012, an epidemiology study was published that concluded there was a significant monotonic exposuredependent increase in stomach cancer risk among 7,814 applicators of methyl bromide Barry et al., 2012. In OPPs Draft HHRA for Methyl Bromide, OPP
reviews all the epidemiological studies for methyl bromide, including the Barry et al. 2012 Agricultural Health Study.
OPP concludes that based on the review of these studies, there is insufficient evidence to suggest a clear associative or causal relationship between exposure to methyl bromide and carcinogenic or non-carcinogenic health outcomes.
According to ATSDR 1992 and the EPA OPP assessment USEPA, 2006c, no studies suggest that a specific subpopulation may be more susceptible to methyl bromide, though there is little information about susceptible lifestages or subpopulations when exposed via the oral route. Because the critical effects of decreased body weight, decreased rate of body weight gain, and decreased food consumption in this study are not specific to a sensitive subpopulation or life stage, the target population of the general adult population was selected in deriving the HRL for regulatory determination. EPAs OPP assessment conducted additional exposure assessments for lifestages that may increase exposure to methyl bromide and concluded that no lifestages have expected exposure greater than 10% of the chronic population-adjusted dose cPAD, including children.
EPA calculated an HRL of 100 mg/L
rounded from 140.8 mg/L based on an EPA OPP assessment cPAD of 0.022 mg/
kg/day and using 2.5 L/day drinking water ingestion, 80 kg body weight, and a 20% RSC factor USEPA, 2006d;
USEPA, 2011, Table 81 and 333.
b Occurrence EPA has determined that methyl bromide does not occur with a frequency and at levels of public health concern at PWSs based on the Agencys evaluation of available occurrence information. The primary data occurrence data for methyl bromide are the 20132015 nationally representative drinking water monitoring data generated through EPAs UCMR 3.
Methyl bromide was not detected in any of the 36,848 UCMR 3 samples collected by 4,916 PWSs serving 241 million people at levels greater than 12 the HRL

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50 mg/L or the HRL 100 mg/L. Methyl bromide was detected in about 0.3%
samples at or above the MRL 0.2 mg/L
USEPA, 2019a; USEPA, 2021a.
Findings from the available ambient water data for methyl bromide are consistent with the results in finished water. Ambient water data in NAWQA
show that methyl bromide was detected in fewer than 1% of samples from fewer than 2% of sites. No detections were greater than the HRL in any of the three cycles. The median concentration among detections were 0.5 mg/L and 0.8
mg/L in Cycle 1 and Cycle 3, respectively. There were no detections in Cycle 2. The results of the NWIS
analysis show that methyl bromide was detected in approximately 0.1% of samples at approximately 0.1% of sites.
The median concentration among detections was 0.6 mg/L.
c Meaningful Opportunity The Agency has determined that regulation of methyl bromide does not present a meaningful opportunity for health risk reduction for persons served by PWSs based on the estimated exposed populations, including sensitive populations. UCMR 3 findings indicate that the estimated population exposed to methyl bromide at levels of public health concern is 0%. As a result, the Agency finds that an NPDWR for methyl bromide does not present a meaningful opportunity for health risk reduction.
d Summary of Public Comments on Methyl Bromide and Agency Responses EPA received several comments on the Agencys evaluation of methyl bromide under section 1412b1A of SDWA, including several comments in support of its preliminary determination not to regulate methyl bromide. Three anonymous members of the public opposed the negative determination of methyl bromide because of their perceptions about its production and use. Specifically, commenters appear to be seeking to prohibit the production and use of methyl bromide.
EPA agrees with the comments that are in support of the negative regulatory determination. Regarding comments that oppose the negative determination because of methyl bromides production and use; the production, importation, use, and disposal of specific chemicals are not regulated by SDWA and therefore are not relevant to this determination. As discussed above, methyl bromide was not found above 12
the HRL in drinking water in any UCMR
3 samples. Furthermore, commenters did not provide any data or other information that suggested that their
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concerns had impacts on the occurrence of methyl bromide in drinking water or discuss any other methyl bromide issues that specifically related to drinkingwater. Hence, commenters concerns are not addressable by this decision not to regulate methyl bromide under SDWA.
E. Metolachlor 1. Description Metolachlor is a chloroacetanilide pesticide that is used as an herbicide for weed control. Initially registered in 1976 for use on turf, metolachlor has more recently been used on corn, cotton, peanuts, pod crops, potatoes, safflower, sorghum, soybeans, stone fruits, tree nuts, non-bearing citrus, nonbearing grapes, cabbage, certain peppers, buffalograss, guymon bermudagrass for seed production, nurseries, hedgerows/fencerows, and landscape plantings. Synonyms for metolachlor include dual and bicep USEPA, 2021a. Metolachlor is expected to have moderate to high persistence in water due to its biodegradation half-life USEPA, 2021a.
2. Agency Findings The Agency is making a determination not to regulate metolachlor with an NPDWR.
Metolachlor does not occur with a frequency and at levels of public health concern. As a result, the Agency finds that an NPDWR does not present a meaningful opportunity for health risk reduction.
a Adverse Health Effects The Agency finds that metolachlor may have adverse effects on the health of persons. The existing toxicological database includes studies evaluating both metolachlor and S-metolachlor.
When combined with the toxicology database for metolachlor, the toxicology database for S-metolachlor is considered complete for risk assessment purposes USEPA, 2018d. In subchronic metolachlor and S-metolachlor USEPA, 1995b; USEPA, 2018d and chronic metolachlor Hazelette, 1989;
Tisdel, 1983; Page, 1981; USEPA, 2018d toxicity studies in dogs and rats, decreased body weight was the most commonly observed effect. Chronic exposure to metolachlor in rats also resulted in increased liver weight and microscopic liver lesions in both sexes USEPA, 2018d. No systemic toxicity was observed in rabbits when metolachlor was administered dermally, though dermal irritation was observed at lower doses USEPA, 2018d. Portal of entry effects e.g., hyperplasia of the squamous epithelium and mucous cell
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