[Risk assessment on noise-induced hearing loss of 488 workers in a petrochemical plant].

Objective: To assess the risk of noise-induced hearing loss in workers from a petrochemical plant. Methods: In October 2020, 488 male workers exposed to noise in a petrochemical plant in Guangdong Province were selected by cluster sampling. Acoustics-Estimation of Noise-Induced Hearing Loss (ISO 1999: 2013) was used to assess the risk of noise-induced hearing loss of workers, and individual fit testing was used to evaluate the sound attenuation obtained by the workers. The risk assessment results and fitness test results of workers with different hearing levels were compared. Results: The average noise exposure equivalent sound level of the workers in the petrochemical plant was 86.7 dB (A) . The median of PARs (personal attenuation ratings) was 16 (4, 23) dB. There were statistically significant differences in age and service years among workers with different hearing results (P<0.05) , but no statistically significant differences in noise intensity and PARs (P>0.05) . According to risk assessment results of ISO 1999: 2013, the current risk of high-frequency hearing loss in 488 workers were negligible risk and acceptable risk. The risk of noise-induced deafness weredivided into three levels: negligible risk in 452 workers (92.7%) , medium risk in 27 workers (5.5%) and high risk in 9 workers (1.8%) . The risk of high-frequency hearing loss in next 5 to 15 years for workers with noise exposure level of >94 to 97 dB and >97 dB or above would be medium risk or above. The risk of noise-induced deafness in next 5 to 15 years for workers exposed to noise withlevel of 91 to 94 dB would be medium risk or above. Conclusion: The risk of noise-induced hearing loss in workers from the petrochemical plant is high in next 5 to 15 years, and noise prevention and control measures need to be strengthened. ISO1999: 2013 assessment method may underestimate the risk of hearing loss among workers.

Birth control techniques in China.

PIP: This article describes the major birth control techniques in use in China, based on data from a contraceptive prevalence study conducted in September, 1982. 118 million of the 170 million married women of child bearing age use birth control. IUD insertion accounts for 50.2% of birth control methods used, tubal ligation accounts for 25.4%, vas deferens ligation 10.0% oral contraceptives (OCs) 8.2%, and condoms 2.0%. A table of clinical data on 9 China made IUDs reveals that pregnancy rates range from 0 (V Cu-300 model) to 5.83% (mixed ring model). A method of IUD insertion immediately after delivery has been researched and adopted, using a silastic Delta IUD with barium added to reduce the high postpartum expulsion rate. fixing the IUD by sutures during Cesarean section has also been developed. Electronmicroscopic studies of the endometrium of women who have used a stainless steel IUD for more than 20 years showes no tendency towards malignancy, nor negative effects on the endocrine functions of the ovaries. 28 million Chinese women have accepted sterilization as of June, 1982. Local anesthesia and the use of acupuncture have reduced complications due to general anesthesia seen previously. Sterilization by means of chemically induced adhesion of Fallopian tube tissue has also been performed successfully; however, this method makes later anastomosis difficult, and is not suitable for young women with only 1 child. Fallopian tube occlusion by means of a silver clip has been performed in 1,128 cases, with a pregnancy rate of only .85%. 10.62 million men have accepted sterilization. While most of the procedures are val ligations, 300,000 men have been sterilized by direct injection of an adhesive agent throuh the skin of the scrotum. No increase in auto immune or vascular disease has been found. 3 low-dose OCs, used since 1969, have proven to be reliable and freer of side effects than higher-dose compounds. In addition, longterm OCs containing quinestrol have been used since 1969 with a success rate of 98.3% women-year. These pills are taken 1x monthly. R and D priority will be given be given to monthly injectable contraceptives; megestrol and norethindrone are the compounds most preferable. In trials so far, the effective rate has been 99.9% with mild side effects. Gossypol, a male contraceptive, has shown an antifertility effect in 99% of 8000 cases studied; however, hypokalemia and irreversibility of spermatogenesis were reported in some cases. Vacuum suction is the most common method for abortion, but Radix Trichosanthis and lilac daphne terpine, traditional abortifacients, anre acceptable for 1st trimester abortions. Prostaglandins are also used.^ieng