UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM 

Date: May 1, 2013 

SUBJECT: Sulfur. Summary of Human Health Risk Assessments to Support Registration Review 

PC Codes: 077501 DP Barcode: 0405975 

Decision No.: 470688 

Petition No.: Not Applicable 

Registration No.: Not Applicable 

Regulatory Action: Registration Review Risk 

Assessment 

Risk Assessment Type: Single Chemical Aggregate 

TXR No.: Not Applicable 

Case No.: 0031 

CAS No.: 7704-34-9 

MRID No.: None 40 CFR: 180.1236 

FROM: 

THROUGH: 

TO: 

Kelly 

Angela 

O'Rourke, 

Howard, PhD, 

Biologist/Risk 

Toxicologist/Risk 

Assessor 

Assessor 

11 ·t-~ 

~ 

/l1 v '. 

~ 

~LBonnie Cropp-Kohlligian, Environmental Scientist · u.A' cU\ -'() 1~t IJRisk Assessment Branch IV 

Health Effects Division (7509P) 

Office of Pesticide Programs 

Elissa Reaves, PhD, Branch Chief 

Risk Assessment Branch IV 

Health Effects Division (7509P) 

Office of Pesticide Programs 

Jose Gayoso, CRM 

Risk Management and Implementation Branch II 

Pesticide Re-evaluation Division (7508P) 

Office of Pesticide Programs 

Attached is a qualitative human health risk assessment to support registration review for 

elemental sulfur as an active ingredient in pesticide formulations. HED has not required 

additional mammalian toxicity data for sulfur and did not conduct a quantitative risk assessment 

for dietary, residential, occupational, or aggregate risk. 

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10.0 

Executive Summary 

Regulatory Recommendations 

Introduction 

Hazard Identification and Dose-Response Assessment 

Dietary Exposure and Risk Assessment 

Residential (Non-Occupational) Exposure/Risk Characterization 

Aggregate Exposure/Risk Characterization 

Cumulative Exposure/Risk Characterization 

Occupational Exposure/Risk Characterization 

References 

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1.0 Executive Summary 

HED has prepared a human health risk assessment to support registration review for the uses of 

elemental sulfur ("sulfur" for the remainder of this memorandum) as an active ingredient in 

pesticide formulations. Because of the low toxicity of sulfur to mammals, HED determined that 

a qualitative risk assessment is appropriate. 

Sulfur is a fungicide/miticide/insecticide which is currently registered for use on a variety of 

field crops, fruits, vegetables, ornamentals, lawns, and golf courses. It is formulated into dusts 

(20 - 99.8% active ingredient), wettable powders, and flowable concentrates. There is potential 

for occupational and residential exposure during handling and postapplication activities. 

Current available toxicity studies and the literature do not indicate any systemic toxicity 

associated with sulfur exposure and no endpoints of toxicological concern have been identified 

for risk assessment purposes. The acute toxicity of sulfur is low. Acute oral toxicity is category 

IV, while acute dermal and inhalation are category III. Sulfur is an eye and skin irritant 

(Category III), but is not a skin sensitizer. A review of incident data indicates that both the 

relative number of reported incidents and the severity of reported health effects are low. In 

general, the dermal, ocular and respiratory symptoms/health effects are reflective of the known 

irritating properties of sulfur. 

A 24-hour restricted entry interval (72 hrs in California) is established for foliar applications, and 

occupational handlers are required to wear personal protective equipment such as coveralls, 

chemical-resistant gloves, and goggles during mixing/loading and application. Sulfur is 

classified as List 4A (minimal risk inert ingredient). Based on the low toxjcity of sulfur to 

mammals, it is currently exempt from the requirement of a tolerance. Concern for residential 

and occupational exposure is low because the labels specify adequate measures to protect from 

the irritating effects of sulfur. 

While exposure to sulfur is possible via the diet, as well as residential and occupational use 

patterns, HED has not identified any toxicological endpoints for human health risk assessment. 

Therefore, HED concludes that no quantitative dietary, residential, aggregate or occupational risk 

assessments are needed. 

Sulfur does not belong to a common mechanism group, and therefore there are no cumulative 

risk concerns. No human studies were used in the sulfur risk assessment. 

2.0 Regulatory Recommendations 

Sufficient data are available to support HED's decision to waive generic mammalian toxicity 

data requirements for sulfur. 

Residues of sulfur are exempt from the requirement of a tolerance under 40 CFR § 180.1236 

when used in accordance with good agricultural practices. Codex has not established maximum 

residue limits for sulfur. Concern for residential and occupational exposure is low because the 

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labels specify adequate measures to protect from the irritating effects of sulfur. Therefore, HED 

has no objection to the continuing registration of sulfur for current uses. 

3.0 Introduction 

Sulfur is a naturally occurring, ubiquitous element in the environment that is also essential to the 

human body and needed at relatively high levels. Sulfur is a fungicide/miticide/insecticide 

which is currently registered for use on a variety of field crops, fruits, vegetables, ornamentals, 

lawns, and golf courses. It is formulated into dusts (20-99.8% ai), wettable powders, and 

flowable concentrates. Sulfur is also mixed with other pesticides/compounds and formulated 

into liquids or powders. There are several registered gas cartridge products where sulfur is 

mixed with potassium nitrate and carbon. These gas cartridge products (sulfur, potassium nitrate 

and carbon mixtures) are designed to undergo chemical reactions and produce toxic fumes after 

ignition. Although no toxicity data are available on the fume by products, HED believes that 

worker and bystander exposure scenarios are not likely to exist based on the use patterns 

(underground uses) and current label precautions. This registration review document is for the 

sulfur active ingredient only. 

Although considered a low toxicity pesticide, elemental sulfur is moderately irritating to the skin 

and is associated with occupationally related irritant dermatitis, and airborne dust is irritating to 

the eyes and the respiratory tract. For the current action, a search of the open literature was 

conducted to identify any new toxicity studies since HED's 2009 memorandum: "Sulfur. Human 

Health Risk Scoping Document in Support of Registration Review - Addendum" (0361 061, R. 

Kent, 1129/2009). None were found to be critical such that a quantitative assessment would be 

required. Additionally, updated incident data indicate that the risk posed to human health by 

sulfur appears low, and there does not appear to be a concern at this time that would warrant 

further investigation. The Agency will evaluate any additional incident information that is 

submitted during the comment period and if a concern is triggered during that time, additional 

analyses will be conducted. 

Potential areas of environmental justice concerns, to the extent possible, were considered in the 

human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal Actions 

to Address Environmental Justice in Minority Populations and Low-Income Populations." The 

Office of Pesticide Programs (OPP) typically considers the highest potential exposures from the 

legal use of a pesticide when conducting human health risk assessments, including, but not 

limited to, people who obtain drinking water from sources near agricultural areas, the variability 

of diets within the U.S., and people who may be exposed when harvesting crops. Should these 

highest exposures indicate potential risks of concern, OPP further refines the risk assessments to 

ensure that the risk estimates are based on the best available information. 

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4.0 Hazard Identification and Dose-Response Assessment 

The toxicology database for sulfur is adequate to support Registration Review. To date, EPA has 

not required additional mammalian toxicity data for sulfur based on the long history of safe use, 

the low acute toxicity and the ubiquitous natural occurrence of sulfur in the environment. 

Acute toxicity studies via the oral, dermal and inhalation routes in rats have been conducted with 

technical sulfur. Sulfur is Category III via the dermal and inhalation routes, and Category IV via 

the oral route. The oral LDso is greater than 5000 mg/kg b.w. and the dermal LD50 is greater than 

2000 mg/kg b.w. in rats. The inhalation LCso is greater than 2.56 mg/L for a 4-hour exposure. 

Topical application of sulfur to rabbit skin resulted in well defined to moderate erythema and 

slight edema at 24 and 48 hours. A primary eye .irritation study in rabbits shows sulfur to be an 

eye irritant. Sulfur is not a skin sensitizer. 

Rats exposed to sulfur via inhalation exhibited body weight depression, decreased blood 

sulfhydryl content, decreased serum peroxidase levels and increased serum albumin. 

A 28-day dermal toxicity study did not find any treatment-related changes in hematological and 

biochemical parameters, organ weights and their ratios in either sex. The only finding was a 

significant increase in the incidence of hyperkeratosis observed microscopically in males and 

females at 1000 mg/kg/day, the highest dose tested. No chronic, reproductive or developmental 

studies were identified in the literature, however, there are no known risks of oncogenic, 

reproductive, or developmental hazards associated with sulfur. 

The genotoxic potential of sulfur dust was tested in vitro in bacteria and mammalian cells and 

technical sulfur was tested in vivo in a micronucleus assay in mice. Sulfur did not induce any 

genotoxicity in any of the systems tested. 

From the available database, there is no evidence to suggest increased susceptibility in infants 

and children. Since sulfur is a naturally occurring, ubiquitous essential element, and since the 

dietary contribution of sulfur from pesticidal uses to the total diet is expected to be low, the 

additional tenfold FQPA safety factor for the protection of infants and children is unnecessary. 

A search of the open literature did not identify any new toxicity data considered critical such that 

a quantitative assessment would be required. Updated incident data indicate that the risk posed 

to human health by sulfur appears low, and there does not appear to be a concern at this time that 

would warrant further investigation. 

In summary, sulfur is a naturally occurring element that is essential to the human body and 

needed at relatively high levels. Current available toxicity studies and the literature do not 

indicate any systemic toxicity associated with sulfur exposure and no endpoints of toxicological 

concern have been identified for risk assessment purposes. Therefore, dietary, residential, and 

occupational risk assessments have not been conducted. The human risks from both dietary and 

residential/occupational exposure to sulfur are considered to be very low. 

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5.0 Dietary Exposure and Risk Assessment 

Residues of sulfur are exempt from the requirement of a tolerance under 40 CFR § 180.1236 

when used in accordance with good agricultural practices. Sulfur occurs naturally in food and is 

abundant in the environment. Residue chemistry studies have not been submitted, and none are 

required. 

While exposure to sulfur could occur via the diet, residues from the pesticidal uses are not likely 

to exceed the levels naturally occurring in food and water. In addition, HED has not identified 

any toxicological endpoints to conduct a human health risk assessment. Therefore, no additional 

data are required and no quantitative dietary assessments are needed. 

6.0 Residential (Non-Occupational) Exposure/Risk Characterization 

While exposure to sulfur could occur in the residential environment, HED has not identified any 

toxicological endpoints to conduct a human health risk assessment. 

HED has no objection to the continuing registration of sulfur because there are adequate label 

recommendations regarding potential eye and skin irritation. 

7.0 Aggregate Exposure/Risk Characterization 

HED has no concern for aggregate risk resulting from the existing uses of sulfur given the lack 

of toxicity and in light of the natural prevalence of this essential nutrient in the environment. 

While both residential and dietary exposures are possible given the use pattern, HED has not 

identified any toxicological points of departure needed to conduct a quantitative human health 

risk assessment. 

8.0 Cumulative Exposure/Risk Characterization 

Section 498(b)(2)(D)(v) ofFFDCA require that, when considering whether to establish, modify, 

or revoke a tolerance, the Agency considers "available information" concerning the cumulative 

effects of a particular pesticide's residues and "other substances that have a common mechanism 

oftoxicity." 

Unlike other pesticides for which EPA has followed a cumulative risk approach based on a 

common mechanism of toxicity, EPA has not made a common mechanism of toxicity fmding as 

to sulfur. In addition, sulfur does not convert to toxic metabolites resulting in other substances. 

For the purposes of this registration review, therefore, EPA has not assumed that sulfur has a 

common mechanism of toxicity with other substances. For information regarding EPA's efforts 

to determine which chemicals have a common mechanism of toxicity and to evaluate the 

cumulative effects of such chemicals, see the policy statements released by EPA's Office of 

Pesticide Programs concerning common mechanism determinations and procedures for 

cumulating effects from substances found to have a common mechanism on EPA's website at 

http://www .epa. gov /pesticides/cumulative/. 

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9.0 Occupational Exposure/Risk Characterization 

Occupational exposure to sulfur is possible due to the registered use pattern. While exposure to 

sulfur could occur in occupational settings, HED has not identified any toxicological endpoints 

to conduct a human health risk assessment. 

Although no systemic toxicological endpoints were identified for sulfur, incidents related to its 

irritating properties (primarily skin and eye) were noted among field workers re-entering treated 

fields in California. To address this, a qualitative occupational risk assessment was conducted 

previously which recommended that a 24-hour restricted entry interval (REI) for foliar 

applications be established. The assessment also recommended that occupational handlers 

should wear personal protective equipment (PPE) such as coveralls, chemical-resistant gloves, 

and goggles during mixing/loading and application based on the California incident data. The 

addition of respirators is not warranted because, based on the data, most incidents involved 

workers re-entering treated fields; the requirement of a respirator is not enforceable once the REI 

has expired. All label requirements previously recommended have been adequately incorporated 

into the most current sulfur product labels. 

10.0 References 

Table 10.1. Memoranda Relevant to Registration Review Risk Assessment 

Author Barcode Da te Title 

M. Rogoff None 2/4/1976 Waiver of Data- Elemental Sulfur 

W. Greear None 7/2511990 Toxicology Summary for the FY'90 Reregistration Decision 

on Sulfur 

P. Perreault None 7/20/1 9900 Assessment of Reentry/Non-Dietary Exposure Data 

Requirements For Sulfur and Recommendations For The 

Reregistration Decision Document 

10M N/A 2005 Dietary reference intakes for Water, Potassium, Sodium 

Chloride, and Sulfate. Washington DC: Food and Nutrition 

Board Institute of Medicine 

European Union N/A 3/ 1/2008 Draft Assessment Report (Public Version): Sulphur. Vol3, 

Annex B, Part 2/A, B.6. 

Y. Donovan D346937 1/17/2008 Sulfur (PC code 077501). Human Health Risk Scoping 

Document in Support of Registration Review 

R. Kent D361061 1/29/2009 Sulfur. Human Health Risk Scoping Document in Support of 

Registration Review - Addendum 

J. Melendez D402561 10/ 12/2012 Rationale for Not Conducting a Drinking Water Analysis for 

Elemental Sulfur for Human Health Risk assessment as a 

Result of Applications of the Chemical as a 

Fungicide/lnsecticide 

S. Recore D410259 3/2 1/2013 Sulfur: Updated Review of Human Incidents 

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