Critical Appraisal Of Benzyl Chloride As Chemical Hazard Biology Essay

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Benzyl chloride is a chemical substance also known as α-chlorotoluene alpha-chlorotoluene and exists in its pure form as a clear colorless liquid (Rossberg, 2006). It has a (CAS) Chemical Abstracts Service Number of 100-44-7 It has a molar mass of 126.58g/mol with a density of 1.100g/cm3. Other properties include a melting point of -39 oC, boiling point of 179 oC and a flashpoint of 165 oF, a density of 1.1 g/mL at 25 oC (lit), vapour density 4.36, vapour pressure 10.3mmHg (60 oC), storage temperature 0-6 oC, water solubility 0.3g/L (20 oC). (U.S. EPA, 1994a HSDB, 1991; Merck, 1989; Sax, 1987; Sax, 1989;)

This production process stated above is the most common but not the only way in which Benzyl chloride can be produced. For example, in Canada the most common method of production of Benzyl chloride is the blanc chloromethylation of benzene (Blanc 1923). Worldwide, about 100,000 tonnes of Benzyl chloride are produced annually.

USES OF BENZYL CHLORIDE

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Benzyl chloride is used industrially as a substance that reacts to form benzyl esters that are then used as plasticizers, perfumes and flavorants. (US EPA, 1986) (HSDB, 1991).

In the cosmetics and beauty industry, Benzyl chloride is used in the manufacture of flavourants for cosmetics and other beauty and household products. It is used along with alcohol groups to protect and stabilize them (US EPA, 1986).

In the pharmaceutical industry it is used mainly in the processing and manufacture of (amphetamine drugs) class B drugs (US EPA, 1986). This makes the sale and storage of benzyl chloride to be closely monitored by drug enforcement agencies in the UK and US. It is also treated with sodium cyanide to produce benzyl cyanide which is then used in most pharmaceutical products.

Benzyl chloride is also less commonly used in the photograph development process and in producing synthetic tannins (US EPA, 1986). Benzyl chloride is also used in organic processes to prevent sticky petroleum resin deposits commonly associated with the oxidative degradation of gasoline and other petroleum products. (HSDB, 1991).

Benzyl chloride is used also in chemical warfare as an irritant gas (commonly called tear gas) that is used to subdue enemies (US EPA, 1986).

HUMAN HEALTH EFFECTS:

Human exposure sources to benzyl chloride are inhalation, ingestion and dermal contact (U.S. EPA, 1994a).

INHALATION Benzyl chloride is known to enter the human body by inhalation of contaminated air that already contains vapours of benzyl chloride, skin contact with benzyl chloride or by ingesting contaminated water. Inhaling air that already has high amounts of benzyl chloride has been known to cause burns, serious respiratory tract irritation, breathing irregularities, damaged lungs, fluid accumulation and lungs swelling (pulmonary edema) and in some situations death. The central nervous system is also affected by exposure to huge amounts of benzyl chloride with symptoms including headache, dizziness and fatigue. INGESTION Studies reveal that ingesting benzyl chloride can cause damage to digestive tract, induce abdominal cramps, nausea, vomiting, diarrhea and mouth burns. Ingesting huge amounts of benzyl chloride can cause damage to the central nervous system and display symptoms close to those exhibited for inhalation when ingested by human beings. DERMAL CONTACT . Benzyl chloride has a corrosive impact on the skin causing burns, itching, blistering and scaling. Benzyl chloride can cause skin irritation and dermatitis due to its skin-permeating quality (US EPA, 1993). Contact with the eyes may result in permanent eye damage because it causes eye inflammation resulting in itching, watering and redness of the eye (IARC, 1982). (Sittig, 1991).Dermal exposure or application of benzyl chloride induced skin tumours according to one study carried out on mice. (XXXXXXXXXXXXXXXX)

CARCINOGENICITY OF BENZYL CHLORIDE . The State of California in the United States has determined that benzyl chloride is a carcinogen (CCR, 1996), however, the International Agency for Research on Cancer has not designated benzyl chloride in terms of its carcinogenicity but in combination with other chlorinated toluenes and benzoyl stating that exposure to benzyl chloride at normal background levels is unlikely to have any adverse effect on human health (IARC, 1987a). . Establishing benzyl chloride as a cause of cancer on the human body has not been conclusive. The main reason for the difficulty in establishing benzyl chloride as a carcinogen is that in studies into most plants and factories where it is produced, the plants also produce other carcinogenic chemicals in their chemical processes (Sakabe et al. 1976 and Sorahan et al. 1983). Therefore this slowed down attempts to identify benzyl chloride as the carcinogen responsible for the cases of cancer.

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Sakabe et al. (1976) studied cancer deaths among the 41 workers in a benzyl chloride production factory in Japan which had 3 cancer deaths from 4 infected employees from 1954 to 1972. Two of these employees died from lung cancer much more than the normal ratio expected from this type of work which is 0.06 calculated according to the Japanese national rate for male lung cancer mortality. The fact that these workers were also exposed to other carcinogens like toulene, benzal chloride, benzotrichloride, benzoyl chloride and other chlorinated toulenes meant this single study could not conclusively ascertain that benzyl chloride was responsible for the high rate of cancer in the employees.

Therefore, due to the lack of cigarette smoking data, the small size of the sample factories and the inability to isolate exposure to benzyl chloride from other halogenated mixtures, human data have been determined to be inconclusive in showing evidence that cancer is caused by exposure to benzyl chloride. (USA EPA, 1999)

However, carcinogenic effect has been identified in animals (Fukuda et al. 1981). In rats, cancers were discovered in their thyroids while in mice, cases of liver, lung and stomach cancer were identified (Coombs 1982b). This made benzyl chloride to be classified as a probable human carcinogen by most environmental and occupational health bodies around the world. In the United States, the United States Environmental Protection Agency (USEPA) and the American Conference of Governmental Industrial Hygienists (ACGIH) have analyzed and classified benzyl chloride and grouped it into category B2, as a suspected human carcinogen by the USEPA and into category A2 by the ACGIH. The European Union groups benzyl chloride into category 3 of carcinogenic substances which are feared to have carcinogenic effects in humans.

HUMAN INHALATION LIMIT

Benzyl chloride has an inhalation acute human exposure limit called Reference Exposure Level (REL) is 50 µg/m3 and a chronic REL of 12 µg/m3 by the California Air Pollution Control Officers Association with the respiratory system used for determining the toxicology value (CAPCOA, 1993) establishing a inhalation potency factor of 4.9 x 10-5 (microgram per cubic meter) -1 (OEHHA, 1994).

Fig. 2 - Health Data from Inhalation Exposurehttp://www.epa.gov/ttn/atw/hlthef/benzylchloride.gif Fig 2. LC - Lethal concentration Health Organisation limit (Source - US EPA)

HUMAN INGESTION LIMIT

The U.S. EPA grouped benzyl chloride into Group B2 which are suspected human carcinogen with an oral unit risk estimate of 4.9 x 10-6 (microgram per liter) -1 this means that cancer risk for a person exposed over a lifetime to 1 µg/m3 of benzyl chloride is estimated to be no greater than 49 in 1 million (US EPA 1994a). They estimate that individuals ingesting water containing benzyl chloride at 0.2 microgram per liter over his or her entire lifetime would have about 1 in 1 million increased chance of developing cancer (U.S. EPA, 1994a). The oral potency factor that has been used as a basis for regulatory action in California is 1.7 x 10-1 (milligram per kilogram per day)-1 (OEHHA, 1994).However, the International Agency for Research on Cancer do not classify benzyl chloride for carcinogenicity (IARC, 1987a).

OCCUPATIONAL HEALTH AND SAFETY LIMITS AND ENVIRONMENTAL LIMITS

In the United States, various organizations set their own safety limit regarding the safety level of human exposure to benzyl chloride. Based on conclusive animal studies, it was discovered that benzyl chloride's major route for exposure is inhalation.

Benzyl chloride's long term and short term exposure limits for occupational health varies between the United Kingdom and other countries. Analysis of data collected by each country based on their current exposure situation the country may take further risk assessment to protect the workplace. The exposure limit in the United Kingdom is half of that in the other countries because the UK Health and Safety Executive analyzed the data from the animal studies to arrive at the decision.

Russia, Sweden and Germany have a short-term exposure limit of 5 mg/m3 for exposure in workplace air which is similar to the 5.2 mg/m3 for the United States (International Labour Office, 1991).

ENVIRONMENTAL HEALTH LIMITS

As margin of safety for indirect exposure is more than 5 x 105, it is currently considered of low potential risk for the population via the environment (UNEP, 1998). The potential environmental distribution of benzyl chloride obtained from a generic fugacity model (Mackey level III) showed the chemical will be distributed mainly to air and water. In Japan, predicted environmental concentration (PEClocal) of the chemical was estimated as 1.8 x 10-3 mg/l from Japanese local exposure scenario.

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The margin of safety of benzyl alcohol for drinking water or fish was calculated as 1.67 x 106 or 7.41 x 105, based on no observed effect level of 100 mg/kg/day. As the margin of safety for benzyl alcohol via indirect exposure is sufficient, it is currently considered of low potential human risk. The daily intake was estimated to be 0.096 mg/kg/day as the worst case, based on the average atmosphere concentration.

The daily intakes through drinking water and fish are estimated as 6.00 x 10-5 mg/kg/day and 1.35 x 10-4 mg/kg/day, respectively, based on the highest predicted environmental concentration of 1.80 x 10-3 mg/l. The U.S. EPA estimates that, if an individual were to ingest water containing benzyl chloride at 0.2 microgram per liter over his or her entire lifetime, that person would theoretically have no more than a 1 in 1 million increased chance of developing cancer (U.S. EPA, 1994a).

COUNTRY

ORGANISATION: DESCRIPTION

DESCRIPTION mg/m3

United States

ACGIH TLV - American Conference of Governmental and Industrial Hygienists' threshold limit value expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effects

5.2 (1ppm)

United States

AIHA ERPG 1 -American Industrial Hygiene Association's emergency response planning guidelines. ERPG 1 is the maximum airborne concentration below which it is believed nearly all individuals could be exposed up to one hour without experiencing other than mild transient adverse health effects or perceiving a clearly defined objectionable odor.

5

(1 ppm)

United States

AIHA ERPG 2 is the maximum airborne concentration below which it is believed nearly all individuals could be exposed up to one hour without experiencing or developing irreversible or other serious health effects that could impair their abilities to take protective action.

50 (10ppm)

United States

NIOSH IDLH - National Institute of Occupational Safety and Health's immediately dangerous to life or health concentration; NIOSH recommended exposure limit to ensure that a worker can escape from an exposure condition that is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from the environment.

50 (10ppm)

United States

NIOSH REL ceiling - NIOSH's recommended exposure limit ceiling; the concentration that should not be exceeded at any time.

5 (1 ppm)

United States

OSHA PEL - Occupational Safety and Health Administration's permissible exposure limit expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effect averaged over a normal 8-h workday or a 40-h workweek

5 (1 ppm)

United Kingdom

HSE - Health and Safety Executive permissible exposure limit expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effect averaged over a normal 8-h workday or a 40-h workweek

2.6

(0.5 ppm)

United Kingdom

HSE - Health and Safety Executive permissible exposure limit expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effect averaged over a 15 minute reference period.

7.9

(1.5 ppm)

Japan

EAJ - Environmental Agency of Japan.

5 (1 ppm)

Russia

Russia Occupational Health Agency permissible exposure limit expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effect averaged over a normal 8-h workday or a 40-h workweek

5 (1 ppm)

Germany

Occupational Health Department - permissible exposure limit expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effect averaged over a normal 8-h workday or a 40-h workweek

5 (1 ppm)

Sweden

Occupational Health Department - permissible exposure limit expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effect averaged over a normal 8-h workday or a 40-h workweek

5 (1 ppm)

Table 1: Showing exposure limit for various organizations in different countries

CONTROL MEASURES

Benzyl chloride is not a known air pollutant. Air Registration Board conducted a study but did not find benzyl chloride in any indoor and outdoor environment with one exception where the mean indoor concentration was 0.85 micrograms per cubic meter (µg/m3) (Sheldon et al, 1992). Any release of benzyl chloride is controlled by the UK Pollution, Prevention and Control (PPC) Regulations 2000, which implement the EC Directive 96/61on Integrated Pollution Prevention and Control (EPA, 2000). In Canada, benzyl chloride risk management requires federal government notification regarding changes in the use pattern for benzyl chloride to ensure the potential for its exposure to the Canadian population is not increased. The Canadian Government added benzyl chloride to the Health Canada Cosmetic Ingredient Hotlist, which is an administrative tool to help manufacturers satisfy the cosmetic safety provisions of section 16 of the Food and Drugs Act. The Government has analyzed benzyl chloride's chances of releasing to the environment as a result of an environmental emergency and has added benzyl chloride to the Environmental Emergency Regulations with a proposed threshold of 4500 kg set through the Risk Evaluation Framework for sections 199 and 200 of CEPA 1999 (Environment Canada 2002).

Benzyl chloride is also monitored by OSPAR Convention which protects the marine environment of the north-east Atlantic Ocean. At normal environmental concentrations benzyl chloride will not cause environmental degradation, however high concentrations from an accidental spill will harm humans and wildlife.

Accidental Release Control Measures . Small Spill: Absorb chemical with inert substance and dispose appropriately Large Spill: . Benzyl chloride is a combustible and corrosive liquid therefore keep away from heat and sources of ignition. Stop leak if without risk. Absorb with dry sand or non-combustible material. Use water spray curtain to divert vapor drift. Do not allow contact with water or into sewers, basements or confined areas; dike if needed. Seek disposal assistance.

Personal Protection for Large Spill: . Splash goggles, full suit, vapor respirator, boots, gloves. A self contained breathing apparatus should be used to avoid inhalation of the product. Consult specialist. First Aid Measures . Eye Contact: Remove contact lenses. Immediately flush eyes with plenty of water for at least 15 minutes. Get medical attention immediately . Skin Contact: Flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Cover the irritated skin with an emollient. Wash clothing and clean shoes before reuse. Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream. Get medical attention immediately.

Inhalation: Remove to fresh air. If not breathing, give artificial respiration (not mouth to mouth or oxygen for serious inhalation move to a safe area, loosen tight clothing such as a collar, tie, belt or waistband. With breathing difficulty, give oxygen.

Ingestion: Do not induce vomiting unless directed by medical professional. Nil by mouth.

Storage:

Keep container in a cool, well-ventilated area. Keep container tightly closed and sealed until ready for use. Avoid all possible sources of ignition (spark or flame).

using data bases such as science direct to find research papers on the effects of this substance to health reflecting on how this research has affected safety limits.

Compare and contrast health and safety limits with environmental limits discussing any variation you find. You should also be considering limits from various countries and not just the UK comparing them with at least another EU state, other non EU European, USA as well as other South American, African or Asian countries.

Consider how your chemical can be effectively controlled though both pollution control regimes or well as health and safety systems.

"a critical appraisal of a chemical hazard though research papers"

Number …………………………………………………………………………

Substance - what is it / what is it used for? (10)

Health effect - health effects, how does it interact with the body, what are the sources of research and can they be used to accurately determine safe limits (40)

Limits - Compare and contrast health and safety limits with environmental limits discussing any variation you find (10)

Control systems - pollution control regimes / health and safety systems. (30)

Reference / presentation (10) total